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Pioneer Series Trust X

Filed: 5 Jun 20, 4:10pm

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED
MANAGEMENT INVESTMENT COMPANIES

Investment Company Act file number 811-21108

Pioneer Series Trust X
(Exact name of registrant as specified in charter)

60 State Street, Boston, MA 02109
(Address of principal executive offices) (ZIP code)

Terrence J. Cullen, Amundi Pioneer Asset Management, Inc.,
60 State Street, Boston, MA 02109
(Name and address of agent for service)


Registrant’s telephone number, including area code:  (617) 742-7825

Date of fiscal year end:  March 31, 2020

Date of reporting period: April 1, 2019 through March 31, 2020

Form N-CSR is to be used by management investment companies to file reports with the Commission not later than 10 days after the transmission to stockholders of any report that is required to be transmitted to stockholders under Rule 30e-1 under the Investment Company Act of 1940 (17 CFR 270.30e-1).  The Commission may use the information provided on Form N-CSR in its regulatory, disclosure review, inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-CSR, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-CSR unless the Form displays a currently valid Office of Management and Budget (“OMB”) control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to Secretary, Securities and Exchange Commission, 450 Fifth Street, NW, Washington, DC 20549-0609.  The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. ss. 3507.



Pioneer Multi-Asset
Ultrashort Income Fund
  
Annual Report | March 31, 2020 
 
Ticker Symbols: 
Class A 
MAFRX 
Class C 
MCFRX 
Class C2 
MAUCX 
Class K 
MAUKX 
Class Y 
MYFRX 
 
Beginning in March 2021, as permitted by regulations adopted by the Securities and Exchange Commission, paper copies of the Fund’s shareholder reports like this one will no longer be sent by mail, unless you specifically request paper copies of the reports from the Fund or from your financial intermediary, such as a broker-dealer, bank or insurance company. Instead, the reports will be made available on the Fund’s website, and you will be notified by mail each time a report is posted and provided with a website link to access the report.
If you already elected to receive shareholder reports electronically, you will not be affected by this change and you need not take any action. You may elect to receive shareholder reports and other communications electronically by contacting your financial intermediary or, if you invest directly with the Fund, by calling 1-800-225-6292.
You may elect to receive all future reports in paper free of charge. If you invest directly with the Fund, you can inform the Fund that you wish to continue receiving paper copies of your shareholder reports by calling 1-800-225-6292. If you invest through a financial intermediary, you can contact your financial intermediary to request that you continue to receive paper copies of your shareholder reports. Your election to receive reports in paper will apply to all funds held in your account if you invest through your financial intermediary or all funds held within the Pioneer Fund complex if you invest directly.






visit us: www.amundipioneer.com/us



  
Table of Contents 
 
 
 
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 1


President’s Letter
Dear Shareholders,
The new decade has arrived delivering a first quarter that will go down in the history books. The beginning of the year seemed to extend the positive market environment of 2019 and then, March roared in like a lion and the COVID-19 pandemic became a global crisis impacting lives and life as we know it. The impact on the global economy from the COVID-19 virus pandemic, while currently unknown, is likely to be considerable. It is clear that several industries have already felt greater effects than others. And the markets, which do not thrive on uncertainty, have been volatile. Our business continuity plan was implemented given the new COVID-19 guidelines, and most of our employees are working remotely. To date, our operating environment has faced no interruption. I am proud of the careful planning that has taken place and confident we can maintain this environment for as long as is prudent. History in the making for a company that first opened its doors way back in 1928.
Since 1928, Amundi Pioneer’s investment process has been built on a foundation of fundamental research and active management, principles which have guided our investment decisions for more than 90 years. We believe active management – that is, making active investment decisions – can help mitigate the potential risks during periods of market volatility. As the early days of 2020 have reminded us, in today’s global economy, investment risk can materialize from a number of factors, including a slowing economy, changing U.S. Federal Reserve policy, oil price shocks, political and geopolitical factors and, unfortunately, major public health concerns such as a viral pandemic.
At Amundi Pioneer, active management begins with our own fundamental, bottom-up research process. Our team of dedicated research analysts and portfolio managers analyze each security under consideration, communicating directly with the management teams of the companies issuing the securities and working together to identify those securities that best meet our investment criteria for our family of funds. Our risk management approach begins with each and every security, as we strive to carefully understand the potential opportunity, while considering any and all risk factors.
2 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

Today, as investors, we have many options. It is our view that active management can serve shareholders well, not only when markets are thriving, but also during periods of market stress. As you consider your long-term investment goals, we encourage you to work with your financial advisor to develop an investment plan that paves the way for you to pursue both your short-term and long-term goals.
We remain confident that the current crisis, like others in human history, will pass, and we greatly appreciate the trust you have placed in us and look forward to continuing to serve you in the future.
Sincerely,
Lisa M. Jones
Head of the Americas, President and CEO of U.S.
Amundi Pioneer Asset Management USA, Inc.
March 31, 2020
Any information in this shareowner report regarding market or economic trends or the factors influencing the Fund’s historical or future performance are statements of opinion as of the date of this report. Past performance is no guarantee of future results.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 3

Portfolio Management Discussion | 3/31/20
In the following interview, portfolio managers Seth Roman, Jonathan Sharkey, Noah Funderburk, and Nicolas Pauwels discuss the factors that influenced the performance of Pioneer Multi-Asset Ultrashort Income Fund during the 12-month period ended March 31, 2020. Mr. Roman, a vice president and a portfolio manager at Amundi Pioneer Asset Management, Inc. (Amundi Pioneer); Mr. Sharkey, a senior vice president and a portfolio manager at Amundi Pioneer; Mr. Funderburk, a vice president and a portfolio manager at Amundi Pioneer; and Mr. Pauwels, a vice president and a portfolio manager at Amundi Pioneer, are responsible for the day-to-day management of the Fund.
Q    How did the Fund perform during the 12-month period ended March 31, 2020?
A    Pioneer Multi-Asset Ultrashort Income Fund’s Class A shares returned -4.02% at net asset value (NAV) during the 12-month period ended March 31, 2020, while the Fund’s benchmark, the ICE Bank of America 3-Month U.S. Dollar LIBOR Index (the ICE BofA Index), returned 2.38%.
During the same period, the average return of the 204 mutual funds in Morningstar’s Ultrashort Bond category was 0.28%.
Q    Can you describe the market environment for fixed-income investors over the 12-month period ended March 31, 2020?
A    Entering the 12-month period, deteriorating global economic growth driven in part by the ongoing U.S.-China trade war was counterbalanced by the continued easing of global monetary policy. U.S. economic growth had held up better than growth in other developed markets during that timeframe, due to healthy consumer confidence data and continued strong employment figures. However, the plummeting manufacturing purchasing managers’ index (PMI) numbers, increased tariffs due to the U.S.-China trade dispute, and a downward trend in non-farm payrolls increased concerns about a U.S. recession. In particular, the on-again, off-again trade negotiations increased market volatility. Responding to those concerns, the U.S. Federal Reserve (Fed) followed up on its July 2019 rate cut with another quarter-point reduction in September. U.S. Treasury yields subsequently declined across the curve and fixed-income returns were buoyed by falling rates.
As the 12-month period drew to a close, the spread to pandemic levels of the COVID-19 virus from China to the rest of the world began to drive performance in the financial markets dramatically downward. Global economies ground to a near halt during March as public health concerns
4 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

led to the rapid implementation by governments and companies of extreme measures focused on virus containment, including the shuttering of businesses deemed non-essential. Compounding the extreme market volatility and economic distress was the plummeting of oil prices to 20-year lows in response to slumping global demand resulting not only from the spread of COVID-19, but also from a supply shock spurred by a price war launched on March 8 between Saudi Arabia and Russia.
Uncertainty over the scope and duration of the pandemic crisis and the need for cash drove wholesale liquidations across most asset classes and a “flight-to-safety” trade that resulted in U.S. Treasury yields hitting historic lows. Significant selling in U.S. dollar (USD) fixed-income markets eventually stressed markets and led to price dislocations in all segments, even Treasury bonds.
Social-distancing and shelter-in-place measures enacted to help curb the spread of COVID-19 had profound economic effects and resulted in significant reductions in services consumption, manufacturing activity, construction, and labor demand. The unprecedented shutting down of much of the U.S. economy due to COVID-19 spurred extraordinary monetary and fiscal policy responses. The Fed jumped into action by dusting off its 2008/2009 policy “playbook” and rapidly rolling out a raft of programs aimed at restoring market liquidity, facilitating credit availability, and boosting investors’ confidence. The measures included reducing the benchmark federal funds rate to zero and committing to making unlimited purchases of U.S. Treasuries and agency mortgage-backed securities (MBS), if necessary, as well as providing support for commercial paper issuance, mutual fund liquidity needs, and the issuance of asset-backed securities (ABS). Additionally, the Fed entered uncharted waters with the announcement on March 23 of purchasing programs in support of investment-grade corporate bonds in both the new-issue and secondary markets. For its part, the U.S. government took steps to backstop the domestic economy with the passage of a stimulus bill in excess of $2 trillion, with the goal of assisting both individuals and businesses. Congressional leaders and the White House also were in discussions about possible further stimulus legislation as the 12-month period ended.
Selling pressures were most pronounced in the short-term markets relevant to most of the Fund’s investments. With “cash as king” in the latter part of the 12-month period, asset managers seeking to meet redemptions or redeploy capital into more deeply discounted securities flooded the market with short-term instruments. At its peak, the liquidity crisis witnessed the inversion of credit curves, with short-term corporates having higher
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 5

spreads than longer-term corporates. (Credit spreads are commonly defined as the differences in yield between Treasuries and other types of fixed-income securities with similar maturities.)
Certain mutual funds began to receive large cash injections from their parents as they faced massive redemptions against the backdrop of a frozen commercial paper market. In turn, banks and broker/dealer balance sheets lacked the capacity to position the flood of assets, and so liquidity started to come at an increasingly high cost. Only the massive, $4 trillion (estimated) monetary stimulus by the Fed helped to restore confidence and liquidity to the market.
Among the U.S. bond market sectors, the liquidity stress was greatest in securitized credit, including ABS, commercial MBS (CMBS), and nonagency MBS, which have typically had a narrower buyer base than corporate bonds. Notably, while post-2008 crisis regulations have caused securitized sectors to offer compelling fundamental value, the same regulations have limited banks' ability to position those securities on their balance sheets, which has greatly exacerbated the price dislocations within the asset class. During the first calendar quarter of 2020, the ABS, MBS, and CMBS markets had to deal with forced selling by real estate investment trusts (REITs), other leveraged investors, and certain mutual funds, not to mention concerns about the impact of COVID-19 on employment and the corresponding ability of homeowners and businesses to pay their residential and commercial obligations.
Q    Can you review the Fund’s principal investment strategies during the 12-month period ended March 31, 2020, and how they affected benchmark-relative performance?
A    Investments in securitized sectors, where the portfolio is overweight compared to its peers, accounted for the majority of the Fund’s underperformance relative to the ICE BofA Index during the 12-month period. Exposures to collateralized mortgage obligations (CMOs), ABS, and CMBS were the primary detractors from benchmark-relative returns.
Within CMOs, the Fund’s allocation to credit-risk-transfer (CRT) securities, which transfer some of the risk of non-payment on residential mortgages from government-sponsored entities to the private sector, had the greatest negative effect on benchmark-relative performance for the 12-month period. Despite the recent underperformance, we believe we would have to experience a significant fall in home prices, similar to the declines of 2008, for the CRTs held by the portfolio to suffer permanent impairment. As a sector within non-agency MBS that has typically been
6 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

more liquid, CRTs may have experienced greater price volatility from forced sellers over the month of March, compared with other segments of the non-agency MBS market.
Underperformance of the Fund’s CMBS holdings primarily reflected the struggles of the portfolio’s allocation to single-asset/single-borrower (SASB) investments. Each SASB securitization represents exposure to a single large property, or to the assets of a single borrower, and can include exposure to collateral such as office towers, suburban office parks, apartment buildings, refrigerated warehouses, and hotels. Because of the concentrated risk, SASBs have tended to feature conservative loan-to-value ratios compared to traditional CMBS instruments. In addition, equity owners of those properties have tended to be well-capitalized firms. The portfolio’s allocation to commercial real estate collateralized loan obligations (CLOs) also detracted from the Fund’s benchmark-relative returns during the 12-month period.
Another detractor from the Fund’s relative returns were its ABS positions backed by consumer loans – where the portfolio’s investments have resided primarily in the most senior tranches – and AAA-rated credit card collateral. At the peak of March's distress and volatility, credit card ABS spreads had widened to historical extremes due to market illiquidity and concerns about consumer delinquencies in the wake of the COVID-19 crisis. We believe the launch of the Fed’s Term Asset-Backed Securities Loan Facility (TALF), expected in early May, could enable purchases of new-issue AAA-rated ABS, and thereby help to restore liquidity to the market.
Other portfolio allocations that had negative effects on the Fund’s benchmark-relative performance during the 12-month period included corporate credit holdings within the financials and industrials sectors, and holdings of bank loans.
Positive contributions to the Fund’s benchmark-relative returns during the 12-month period were led by an allocation to insurance-linked securities (ILS), which are sponsored by property-and-casualty insurers seeking to mitigate the effects of having to pay claims in the wake of natural disasters. The ostensibly exotic ILS market, which has typically had little or no correlation to other financial markets, proved to have relatively resilient liquidity during the extremely volatile market environment we experienced during the first calendar quarter of 2020. ILS had also displayed similar resiliency during the global financial crisis almost 12 years ago.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 7

Q    Can you discuss the factors that affected the Fund’s income-generation/ distributions* to shareholders, either positively or negatively, during the 12-month period ended March 31, 2020?
A    Throughout the period, we had invested the Fund in floating-rate issues with interest rates tied to London Interbank Offered Rates (LIBOR), or other short-term reference rates. The Fund’s income remained quite steady over the 12-month period, despite a decline in short-term LIBOR rates.
Historically, changes to the Fund’s dividend yield have tended to lag changes in LIBOR rates.
Q    Did the Fund have any exposure to derivatives during the 12-month period ended March 31, 2020?
A    No, the Fund had no derivatives exposure during the 12-month period.
Q    What is your assessment of the current investment environment in the fixed-income markets, and how have you positioned the portfolio for that environment?
A    Entering the Fund’s new fiscal year, we have continued to hold significant exposure to securitized credit within the portfolio. As noted previously, the sector suffered late in the 12-month period due to concerns about liquidity and fundamentals, with the latter focused on the ability of U.S. consumers to remain current on their credit card, auto, and home payments, and of businesses to pay their rents. With that said, on the consumer side, we believe securitized credit may benefit from consumers’ markedly higher aggregate savings rates, record levels of total wealth, and significantly lower levels of leverage compared with 2008. In general, relative to 2008, we believe the securitized credit market reflects much stronger underwriting standards, with greater risk-retention by issuers, more stringent rating-agency standards, and much higher levels of credit protection. In recalibrating credit protections, the rating agencies have sought to ensure that investment-grade-rated MBS issues would not suffer permanent impairment when facing a downside scenario such as occurred in 2008. It is important to note that, in the overvalued market of 2008, home prices eventually declined by approximately 30%, and commercial real estate prices declined by approximately 40%. We believe that both residential and commercial real estate valuations are much more reasonable than they were in those days and that, while there are no guarantees, neither housing nor commercial real estate should suffer the dramatic declines experienced during the 2008/09 financial crisis.
*  Distributions and dividend yields are not guaranteed.
8 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

Given currently wide credit spreads, we believe that corporate credit offers attractive investment opportunities. We believe the wider spreads for investment-grade corporates have resulted primarily from the aforementioned liquidity squeeze, rather than from fundamental factors. In addition, the Fund’s management team believes the financial sector, particularly U.S. and European banks, has continued to offer value. Banks have significantly improved their balance sheets and capital positions over the past several years, and have been subject to increased regulatory oversight.
The Fund’s current positioning is designed to allow it to possibly benefit from any potential recovery in credit markets. With investment-grade corporate spreads well above their long-term average, we believe investors have been receiving fair compensation for taking on credit risk. As the year progresses, we think we could see further spread compression should the global economy begin to recover.
Importantly, we do not believe the Fund faces any material, permanent impairment of capital in the current difficult environment. Given the greater credit sensitivity of the portfolio relative to the benchmark ICE BofA Index, we believe the Fund has the potential to generate solid benchmark-relative performance over the longer term.
Please refer to the Schedule of Investments on pages 21–89 for a full listing of Fund securities.
All investments are subject to risk, including the possible loss of principal. In the past several years, financial markets have experienced increased volatility and heightened uncertainty. The market prices of securities may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political, or regulatory conditions, recessions, inflation, changes in interest or currency rates, lack of liquidity in the bond markets, the spread of infectious illness or other public health issues or adverse investor sentiment. These conditions may continue, recur, worsen or spread.
The Fund has the ability to invest in a wide variety of debt securities.
The Fund may invest in underlying funds (including ETFs). In addition to the Fund’s operating expenses, you will indirectly bear the operating expenses of investments in any underlying funds.
The Fund and some of the underlying funds may utilize strategies that have a leveraging effect on the Fund, which increases the volatility of investment returns and subjects the Fund to magnified losses if the Fund’s or an underlying fund’s investments decline in value.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 9

The Fund and some of the underlying funds may use derivatives, such as options and futures, which can be illiquid, may disproportionately increase losses, and have a potentially large impact on Fund performance.
The Fund may invest in inflation-linked securities. As inflationary expectations increase, inflation-linked securities may become more attractive, because they protect future interest payments against inflation. Conversely, as inflationary concerns decrease, inflation-linked securities will become less attractive and less valuable.
The Fund may invest in credit default swaps, which may in some cases be illiquid, and they increase credit risk since the Fund has exposure to both the issuer of the referenced obligation and the counterparty to the credit default swap.
The Fund may invest in subordinated securities which may be disproportionately adversely affected by a default or even a perceived decline in creditworthiness of the issuer.
The Fund may invest in floating-rate loans. The value of collateral, if any, securing a floating-rate loan can decline or may be insufficient to meet the issuer’s obligations or may be difficult to liquidate.
The Fund may invest in insurance-linked securities. The return of principal and the payment of interest and/or dividends on insurance-linked securities are contingent on the non-occurrence of a pre-defined “trigger” event, such as a hurricane or an earthquake of a specific magnitude.
The Fund may invest in zero-coupon bonds and payment-in-kind securities, which may be more speculative and fluctuate more in value than other fixed income securities. The accrual of income from these securities are payable as taxable annual dividends to shareholders.
Investments in equity securities are subject to price fluctuation.
International investments are subject to special risks including currency fluctuations, social, economic and political uncertainties, which could increase volatility. These risks are magnified in emerging markets.
Investments in fixed-income securities involve interest rate, credit, inflation, and reinvestment risks. As interest rates rise, the value of fixed income securities generally falls.
The Fund may invest in mortgage-backed securities, which during times of fluctuating interest rates may increase or decrease more than other fixed-income securities. Mortgage-backed securities are also subject to pre-payments.
10 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

Prepayment risk is the chance that an issuer may exercise its right to prepay its security, if falling interest rates prompt the issuer to do so. Forced to reinvest the unanticipated proceeds at lower interest rates, the Fund would experience a decline in income and lose the opportunity for additional price appreciation.
High yield bonds possess greater price volatility, illiquidity, and possibility of default.
There may be insufficient or illiquid collateral securing the floating rate loans held within the Fund. This may reduce the future redemption or recovery value of such loans.
The Fund may have disadvantaged access to confidential information that could be used to assess a loan issuer, as Amundi Pioneer normally seeks to avoid receiving material, non-public information.
The Fund is not a money market fund.
These risks may increase share price volatility.
There is no assurance that these and other strategies used by the Fund or underlying funds will be successful.
Please see the prospectus for a more complete discussion of the Fund’s risks.
Before investing, consider the product’s investment objectives, risks, charges and expenses. Contact your advisor or Amundi Pioneer Asset Management, Inc., for a prospectus or summary prospectus containing this information. Read it carefully.
Any information in this shareholder report regarding market or economic trends or the factors influencing the Fund’s historical or future performance are statements of opinion as of the date of this report. Past performance is no guarantee of future results.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 11

Portfolio Summary | 3/31/20


Portfolio Diversification

(As a percentage of total investments)*


† Amount rounds to less than 0.1%.

10 Largest Holdings
(As a percentage of total investments)*
   
1. 
U.S. Treasury Floating Rate Notes, 0.385% (3 Month U.S. Treasury Bill Money 
 
 
Market Yield + 30 bps), 10/31/21 
10.99% 
2. 
Tidewater Auto Receivables Trust, Series 2020-AA, Class A2, 1.39%, 8/15/24 (144A) 
  0.65 
3. 
PFS Financing Corp., Series 2019-B, Class A, 1.255% (1 Month USD LIBOR + 
 
 
55 bps), 9/15/23 (144A) 
  0.62 
4. 
First Investors Auto Owner Trust, Series 2020-1A, Class A, 1.49%, 1/15/25 (144A) 
  0.58 
5. 
Verizon Owner Trust, Series 2020-A, Class A1B, 1.043% (1 Month USD LIBOR + 
 
 
27 bps), 7/22/24 
  0.55 
6. 
Veros Automobile Receivables Trust, Series 2020-1, Class A, 1.67%, 9/15/23 (144A)
  0.55 
7. 
Upstart Securitization Trust, Series 2020-1, Class A, 2.322%, 4/22/30 (144A) 
  0.55 
8. 
LSTAR Securities Investment, Ltd., Series 2019-4, Class A1, 3.081% (1 Month 
 
 
USD LIBOR + 150 bps), 5/1/24 (144A) 
  0.54 
9. 
Federal National Mortgage Association, 0.23% (SOFRRATE + 22 bps), 3/16/22 
  0.53 
10. 
Consumer Loan Underlying Bond Club Certificate Issuer Trust, Series 2019-HP1, 
 
 
Class A, 2.59%, 12/15/26 (144A) 
  0.50 
 
*  Excludes temporary cash investments and all derivative contracts except for options purchased. The Fund is actively managed, and current holdings may be different. The holdings listed should not be considered recommendations to buy or sell any securities.
12 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

Prices and Distributions | 3/31/20


Net Asset Value per Share
   
Class 3/31/20 3/31/19 
$9.26 $9.92 
$9.26 $9.91 
C2 $9.27 $9.91 
$9.29 $9.93 
$9.27 $9.92 
 
Distributions per Share:* 4/1/19 – 3/31/20
    
 
Net Investment Short-Term Long-Term 
Class Income Capital Gains Capital Gains 
$0.2734 $ — $ — 
$0.2410 $ — $ — 
C2 $0.2418 $ — $ — 
$0.2950 $ — $ — 
$0.2881 $ — $ — 
 
*  The amount of distributions made to shareowners during the year was in excess of the net investment income earned by the Fund during the year.
The ICE Bank of America U.S. Dollar 3-Month LIBOR Index is an unmanaged index that tracks the performance of a synthetic asset paying the London Interbank Offered Rate (LIBOR), with a constant 3-month average maturity. The index is based on the assumed purchase at par value of a synthetic instrument having exactly its stated maturity and with a coupon equal to that day’s 3-month LIBOR rate. Index returns assume reinvestment of dividends and, unlike Fund returns, do not reflect any fees, expenses or sales charges. It is not possible to invest directly in an index.
The index defined here pertains to the “Value of $10,000 Investment” and “Value of $5 Million Investment” charts on pages 14–18.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 13

  
Performance Update | 3/31/20 
Class A Shares 
 
Investment Returns
The mountain chart on the right shows the change in value of a $10,000 investment made in Class A shares of Pioneer Multi-Asset Ultrashort Income Fund at public offering price during the periods shown, compared to that of the ICE Bank of America (BofA) U.S. Dollar 3-Month LIBOR Index.
    
Average Annual Total Returns 
 
(As of March 31, 2020) 
 
 
 
 
 
ICE BofA 
 
 
 
U.S. 
 
Net Public Dollar 
 
Asset Offering 3-Month 
 
Value Price LIBOR 
Period (NAV) (POP)* Index 
Life-of-Class 
 
 
 
(4/29/11) 
0.85% 0.57% 
0.94% 
5 years 
0.50 
-0.01 
1.42 
1 year 
-4.02 
-4.02 
2.38 
 
 
Expense Ratio 
 
 
(Per prospectus dated August 1, 2019) 
 
Gross 
 
 
 
0.59% 
 
 
 
 
Call 1-800-225-6292 or visit www.amundipioneer.com/us for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted.
The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost.
NAV results represent the percent change in net asset value per share.
*POP returns shown above reflect the deduction of the maximum 2.50% front-end sales charge on Class A shares purchased prior to February 5, 2018.
All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ.
Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information.
The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares.
Please refer to the financial highlights for a more current expense ratio.
14 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

  
Performance Update | 3/31/20 
Class C Shares 
 
Investment Returns
The mountain chart on the right shows the change in value of a $10,000 investment made in Class C shares of Pioneer Multi-Asset Ultrashort Income Fund during the periods shown, compared to that of the ICE Bank of America (BofA) U.S. Dollar 3-Month LIBOR Index.
   
Average Annual Total Returns 
 
(As of March 31, 2020) 
 
 
 
ICE BofA 
 
 
U.S. 
 
Net Dollar 
 
Asset 3-Month 
 
Value LIBOR 
Period (NAV) Index 
Life-of-Class 
 
 
(4/29/11) 
0.48% 
0.94% 
5 years 
0.20 
1.42 
1 year 
-4.24 
2.38 
 
 
Expense Ratio 
 
 
(Per prospectus dated August 1, 2019) 
 
Gross 
 
 
0.91% 
 
 
 
Call 1-800-225-6292 or visit www.amundipioneer.com/us for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted.
The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost.
NAV results represent the percent change in net asset value per share. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ.
Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information.
The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares.
Please refer to the financial highlights for a more current expense ratio.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 15

  
Performance Update | 3/31/20 
Class C2 Shares 
 
Investment Returns
The mountain chart on the right shows the change in value of a $10,000 investment made in Class C2 shares of Pioneer Multi-Asset Ultrashort Income Fund during the periods shown, compared to that of the ICE Bank of America (BofA) U.S. Dollar 3-Month LIBOR Index.
    
Average Annual Total Returns 
 
(As of March 31, 2020) 
 
 
 
 
ICE BofA 
 
 
 
U.S. 
 
 
 
Dollar 
 
 
 
3-Month 
 
If If LIBOR 
Period Held Redeemed Index 
Life-of-Fund
 
 
 
(4/29/11) 
0.49% 0.49% 
0.94% 
5 years 
0.22 0.22 
1.42 
1 year 
-4.13 
-4.13 
2.38 
 
 
Expense Ratio 
 
 
(Per prospectus dated August 1, 2019) 
 
Gross 
 
 
 
0.91% 
 
 
 
 
Call 1-800-225-6292 or visit www.amundipioneer.com/us for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted.
The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost.
Class C2 shares held for less than 1 year are subject to a 1% contingent deferred sales charge (CDSC). “If Held” results represent the percentage change in net asset value per share. “If Redeemed” returns would have been lower had sales charges been reflected. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ.
The performance shown for periods prior to the commencement of operations of Class C2 shares on August 1, 2013, is the net asset value performance of the Fund’s Class C shares, which has not been restated to reflect any differences in expenses. For the period beginning August 1, 2013, the actual performance of Class C2 shares is reflected.
Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information.
The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares.
Please refer to the financial highlights for a more current expense ratio.
16 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

  
Performance Update | 3/31/20 
Class K Shares 
 
Investment Returns
The mountain chart on the right shows the change in value of a $5 million investment made in Class K shares of Pioneer Multi-Asset Ultrashort Income Fund during the periods shown, compared to that of the ICE Bank of America (BofA) U.S. Dollar 3-Month LIBOR Index.
   
Average Annual Total Returns 
 
(As of March 31, 2020) 
 
 
 
ICE BofA 
 
 
U.S. 
 
Net Dollar 
 
Asset 3-Month 
 
Value LIBOR 
Period (NAV) Index 
Life-of-Fund
 
 
(4/29/11) 
1.07% 
0.94% 
5 years 
0.77 
1.42 
1 year 
-3.60 
2.38 
 
 
Expense Ratio 
 
 
(Per prospectus dated August 1, 2019) 
 
Gross 
 
 
0.37% 
 
 
 
Call 1-800-225-6292 or visit www.amundipioneer.com/us for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted.
The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost.
The performance shown for Class K shares for the period prior to the commencement of operations of Class K shares on December 20, 2012, is the net asset value performance of the Fund’s Class A shares, which has not been restated to reflect any differences in expenses, including Rule 12b-1 fees applicable to Class A shares. Since fees for Class A shares generally are higher than those of Class K shares, the performance of Class K shares prior to their inception would have been higher than the performance shown. For the period beginning on December 20, 2012, the actual performance of Class K shares is reflected. Class K shares are not subject to sales charges and are available for limited groups of eligible investors, including institutional investors. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ.
Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information.
The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares.
Please refer to the financial highlights for a more current expense ratio.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 17

  
Performance Update | 3/31/20 
Class Y Shares 
 
Investment Returns
The mountain chart on the right shows the change in value of a $5 million investment made in Class Y shares of Pioneer Multi-Asset Ultrashort Income Fund during the periods shown, compared to that of the ICE Bank of America (BofA) U.S. Dollar 3-Month LIBOR Index.
   
Average Annual Total Returns 
 
(As of March 31, 2020) 
 
 
 
ICE BofA 
 
 
U.S. 
 
Net Dollar 
 
Asset 3-Month 
 
Value LIBOR 
Period (NAV) Index 
Life-of-Class 
 
 
(4/29/11) 
1.02% 
0.94% 
5 years 
0.64 
1.42 
1 year 
-3.78 
2.38 
 
 
Expense Ratio 
 
 
(Per prospectus dated August 1, 2019) 
 
Gross 
 
 
0.45% 
 
 
 
Call 1-800-225-6292 or visit www.amundipioneer.com/us for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted.
The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost.
Class Y shares are not subject to sales charges and are available for limited groups of eligible investors, including institutional investors. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ.
Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information.
The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares.
Please refer to the financial highlights for a more current expense ratio.
18 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

Comparing Ongoing Fund Expenses
As a shareowner in the Fund, you incur two types of costs:
(1)   ongoing costs, including management fees, distribution and/or service (12b-1) fees, and other Fund expenses; and
(2)   transaction costs, including sales charges (loads) on purchase payments.
This example is intended to help you understand your ongoing expenses (in dollars) of investing in the Fund and to compare these costs with the ongoing costs of investing in other mutual funds. The example is based on an investment of $1,000 at the beginning of the Fund’s latest six-month period and held throughout the six months.
Using the Tables
Actual Expenses
The first table below provides information about actual account values and actual expenses. You may use the information in this table, together with the amount you invested, to estimate the expenses that you paid over the period as follows:
(1)   Divide your account value by $1,000
Example: an $8,600 account value ÷ $1,000 = 8.6
(2)   Multiply the result in (1) above by the corresponding share class’s number in the third row under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.
Expenses Paid on a $1,000 Investment in Pioneer Multi-Asset Ultrashort Income Fund
Based on actual returns from October 1, 2019 through March 31, 2020.
      
Share Class C2 
Beginning Account 
$1,000.00 $1,000.00 $1,000.00 $1,000.00 $1,000.00 
Value on 10/1/19 
 
 
 
 
 
Ending Account Value 
$945.15 $944.47 $945.56 $948.26 $945.84 
(after expenses) 
 
 
 
 
 
on 3/31/20 
 
 
 
 
 
Expenses Paid 
$2.82 $4.33 $4.28 $1.75 $2.14 
During Period* 
 
 
 
 
 
 
*  Expenses are equal to the Fund's annualized expense ratio of 0.58%, 0.89%, 0.88%, 0.36% and 0.44% for class A, C, C2, K, and Y shares, respectively, multiplied by the average account value over the period, multiplied by 183/366 (to reflect the partial year period).
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 19

Hypothetical Example for Comparison Purposes
The table below provides information about hypothetical account values and hypothetical expenses based on the Fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the Fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period.
You may use this information to compare the ongoing costs of investing in the Fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds.
Please note that the expenses shown in the tables are meant to highlight your ongoing costs only and do not reflect any transaction costs, such as sales charges (loads) that are charged at the time of the transaction. Therefore, the table below is useful in comparing ongoing costs only and will not help you determine the relative total costs of owning different funds. In addition, if these transaction costs were included, your costs would have been higher.
Expenses Paid on a $1,000 Investment in Pioneer Multi-Asset Ultrashort Income Fund
Based on a hypothetical 5% return per year before expenses, reflecting the period from October 1, 2019 through March 31, 2020.
      
Share Class C2 
Beginning Account 
$1,000.00 $1,000.00 $1,000.00 $1,000.00 $1,000.00 
Value on 10/1/19 
 
 
 
 
 
Ending Account Value 
$1,022.10 $1,020.55 $1,020.60 $1,023.20 $1,022.80 
(after expenses) 
 
 
 
 
 
on 3/31/20 
 
 
 
 
 
Expenses Paid 
$2.93 $4.50 $4.45 $1.82 $2.23 
During Period* 
 
 
 
 
 
 
*  Expenses are equal to the Fund's annualized expense ratio of 0.58%, 0.89%, 0.88%, 0.36% and 0.44% for class A, C, C2, K, and Y shares, respectively, multiplied by the average account value over the period, multiplied by 183/366 (to reflect the partial year period).
20 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

Schedule of Investments | 3/31/20
    
Shares  
 
Value 
 
 UNAFFILIATED ISSUERS — 96.2% 
 

 COMMON STOCK — 0.0%† of Net Assets 
 
 Transportation Infrastructure — 0.0%† 
 
2,377(a)  
Syncreon Group 
$ 12,678 
 
 Total Transportation Infrastructure $ 12,678 
 
 TOTAL COMMON STOCK 
 
 
 
(Cost $33,278) 
$ 12,678 

Principal  
 
 
Amount  
 
 
USD ($)  
 
 

 ASSET BACKED SECURITIES — 33.5% 
 
 of Net Assets 
 
244,936(b)  
321 Henderson Receivables I LLC, Series 2004-A, 
 
 
 
Class A1, 1.055% (1 Month USD LIBOR + 
 
 
 
35 bps), 9/15/45 (144A) 
$ 233,344 
2,045,570(b)  
321 Henderson Receivables I LLC, Series 2005-1A, 
 
 
 
Class A1, 0.935% (1 Month USD LIBOR + 
 
 
 
23 bps), 11/15/40 (144A) 
1,883,304 
377,753(b)  
321 Henderson Receivables I LLC, Series 2006-1A, 
 
 
 
Class A1, 0.905% (1 Month USD LIBOR + 
 
 
 
20 bps), 3/15/41 (144A) 
363,783 
926,402(b)  
321 Henderson Receivables I LLC, Series 2006-2A, 
 
 
 
Class A1, 0.905% (1 Month USD LIBOR + 
 
 
 
20 bps), 6/15/41 (144A) 
865,057 
1,355,680(b)  
321 Henderson Receivables I LLC, Series 2006-4A, 
 
 
 
Class A1, 0.905% (1 Month USD LIBOR + 
 
 
 
20 bps), 12/15/41 (144A) 
1,317,248 
379,474(b)  
321 Henderson Receivables I LLC, Series 2007-1A, 
 
 
 
Class A1, 0.905% (1 Month USD LIBOR + 
 
 
 
20 bps), 3/15/42 (144A) 
336,655 
1,310,785(b)  
321 Henderson Receivables II LLC, Series 2006-3A, 
 
 
 
Class A1, 0.905% (1 Month USD LIBOR + 
 
 
 
20 bps), 9/15/41 (144A) 
1,217,030 
1,893,415(b)  
ABFC Trust, Series 2004-OPT2, Class M1, 1.772% 
 
 
 
(1 Month USD LIBOR + 83 bps), 8/25/33 
1,778,367 
568,708(b)  
ABFC Trust, Series 2005-WMC1, Class M2, 1.622% 
 
 
 
(1 Month USD LIBOR + 68 bps), 6/25/35 
563,610 
7,756,469  
ACC Trust, Series 2019-2, Class A, 2.82%, 
 
 
 
2/21/23 (144A) 
7,729,154 
842,005(b)  
ACE Securities Corp. Home Equity Loan Trust, Series 
 
 
 
2005-WF1, Class M2, 1.607% (1 Month USD LIBOR 
 
 
 
+ 66 bps), 5/25/35 
847,818 
1,585,645(b)  
Aegis Asset Backed Securities Trust Mortgage Pass-Through 
 
 
 
Ctfs, Series 2004-3, Class M1, 1.847% 
 
 
 
(1 Month USD LIBOR + 90 bps), 9/25/34 
1,480,821 
2,540,509(b)  
Aegis Asset Backed Securities Trust Mortgage Pass-Through 
 
 
 
Ctfs, Series 2004-4, Class M1, 1.847% 
 
 
 
(1 Month USD LIBOR + 90 bps), 10/25/34 
2,388,077 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 21

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
4,854  
American Credit Acceptance Receivables Trust, 
 
 
 
Series 2017-2, Class C, 2.86%, 6/12/23 (144A) 
$ 4,851 
308,418  
American Credit Acceptance Receivables Trust, 
 
 
 
Series 2018-3, Class B, 3.49%, 6/13/22 (144A) 
308,243 
8,000,000  
American Credit Acceptance Receivables Trust, 
 
 
 
Series 2020-1, Class B, 2.08%, 12/13/23 (144A) 
7,721,058 
806,501(b)  
Ameriquest Mortgage Securities, Inc. Asset-Backed 
 

 
Pass-Through Ctfs, Series 2005-R3, Class M2,
 
 
 
1.652% (1 Month USD LIBOR + 71 bps), 5/25/35 
804,550 
21,851(b)  
Ameriquest Mortgage Securities, Inc. Asset-Backed 
 

 
Pass-Through Ctfs, Series 2005-R10, Class M1,
 
 
 
1.357% (1 Month USD LIBOR + 41 bps), 1/25/36 
21,764 
68,915(b)  
Amortizing Residential Collateral Trust, Series 2002-BC5, 
 
 
 
Class M1, 1.982% (1 Month USD LIBOR + 
 
 
 
104 bps), 7/25/32 
65,010 
6,695,120  
Amur Equipment Finance Receivables V LLC, 
 
 
 
Series 2018-1A, Class A2, 3.24%, 12/20/23 (144A) 
6,685,276 
6,422,003  
Amur Equipment Finance Receivables VI LLC, 
 
 
 
Series 2018-2A, Class A2, 3.89%, 7/20/22 (144A) 
6,543,879 
4,000,000  
Amur Equipment Finance Receivables VII LLC, 
 
 
 
Series 2019-1A, Class B, 2.8%, 3/20/25 (144A) 
3,943,272 
618,750(b)  
Annisa CLO, Ltd., Series 2016-2A, Class X, 2.419% 
 
 
 
(3 Month USD LIBOR + 60 bps), 7/20/31 (144A) 
618,723 
375,000(b)  
Apidos CLO XV, Series 2013-15A, Class XRR, 2.419% 
 
 
 
(3 Month USD LIBOR + 60 bps), 4/20/31 (144A) 
374,996 
964,286(b)  
Apidos CLO XXIX, Series 2018-29A, Class X, 2.344% 
 
 
 
(3 Month USD LIBOR + 55 bps), 7/25/30 (144A) 
964,278 
2,600,000(b)  
Apidos CLO XXXII, Series 2019-32A, Class X, 2.333% 
 
 
 
(3 Month USD LIBOR + 65 bps), 1/20/33 (144A) 
2,599,943 
13,978,209  
Aqua Finance Trust, Series 2019-A, Class A, 3.14%, 
 
 
 
7/16/40 (144A) 
13,922,423 
146,875(b)  
Ares XXXVIII CLO, Ltd., Series 2015-38A, Class X, 2.319% 
 
 
 
(3 Month USD LIBOR + 50 bps), 4/20/30 (144A) 
146,874 
225,000(b)  
Ares XXXVR CLO, Ltd., Series 2015-35RA, Class X, 2.481% 
 
 
 
(3 Month USD LIBOR + 65 bps), 7/15/30 (144A) 
224,999 
1,021,875(b)  
Argent Securities, Inc. Asset-Backed Pass-Through 
 
 
 
Certificates, Series 2004-W11, Class M2, 
 
 
 
1.997% (1 Month USD LIBOR + 
 
 
 
105 bps), 11/25/34 
998,290 
29,745(b)  
Argent Securities, Inc. Asset-Backed Pass-Through 
 
 
 
Certificates, Series 2005-W2, Class A1, 
 
 
 
1.207% (1 Month USD LIBOR + 
 
 
 
26 bps), 10/25/35 
29,700 
95,106(b)  
Argent Securities, Inc. Asset-Backed Pass-Through 
 
 
 
Certificates, Series 2005-W3, Class A2D, 
 
 
 
1.287% (1 Month USD LIBOR + 
 
 
 
34 bps), 11/25/35 
93,191 
 
The accompanying notes are an integral part of these financial statements.
22 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
320,491  
ARI Fleet Lease Trust, Series 2016-A, Class A3, 2.11%, 
 
 
 
7/15/24 (144A) 
$ 320,075 
284,642  
ARI Fleet Lease Trust, Series 2017-A, Class A2, 1.91%, 
 
 
 
4/15/26 (144A) 
284,077 
9,044,762  
Arivo Acceptance Auto Loan Receivables Trust, 
 
 
 
Series 2019-1, Class A, 2.99%, 7/15/24 (144A) 
8,872,622 
5,229,405  
Ascentium Equipment Receivables, Series 2019-1A, 
 
 
 
Class A2, 2.84%, 6/10/22 (144A) 
5,216,683 
20,000,000  
Ascentium Equipment Receivables, Series 2019-2A, 
 
 
 
Class A2, 2.24%, 6/10/22 (144A) 
20,202,394 
307,767(b)  
Asset Backed Securities Corp. Home Equity Loan Trust, 
 

 
Series 2005-HE4, Class M4, 1.892% (1 Month
 
 
 
USD LIBOR + 95 bps), 5/25/35 
305,312 
75,493(b)  
Asset Backed Securities Corp. Home Equity Loan Trust, 
 

 
Series 2006-HE1, Class A3, 1.147% (1 Month
 
 
 
USD LIBOR + 20 bps), 1/25/36 
74,970 
22,302(b)  
Asset-Backed Pass-Through Certificates, Series 2004-R2, 
 
 
 
Class A1A, 1.637% (1 Month USD LIBOR + 
 
 
 
69 bps), 4/25/34 
21,936 
234,816(b)  
Asset-Backed Pass-Through Certificates, Series 2004-R2, 
 
 
 
Class A1B, 1.567% (1 Month USD LIBOR + 
 
 
 
62 bps), 4/25/34 
230,803 
1,658,571(b)  
ASSURANT CLO III, Ltd., Series 2018-2A, Class X, 2.519% 
 
 
 
(3 Month USD LIBOR + 70 bps), 10/20/31 (144A) 
1,658,560 
16,422,533(b)  
Atlas Senior Loan Fund III, Ltd., Series 2013-1A, 
 
 
 
Class AR, 2.522% (3 Month USD LIBOR + 
 
 
 
83 bps), 11/17/27 (144A) 
15,435,440 
959,751(b)  
Atlas Senior Loan Fund XII, Ltd., Series 2018-12A, 
 
 
 
Class X, 2.551% (3 Month USD LIBOR + 
 
 
 
75 bps), 10/24/31 (144A) 
959,742 
880,147  
Avant Loans Funding Trust, Series 2018-B, Class A, 
 
 
 
3.42%, 1/18/22 (144A) 
866,825 
4,223,271  
Avant Loans Funding Trust, Series 2019-A, Class A, 
 
 
 
3.48%, 7/15/22 (144A) 
4,108,857 
6,183,482  
Avant Loans Funding Trust, Series 2019-B, Class A, 
 
 
 
2.72%, 10/15/26 (144A) 
6,017,557 
1,015,589  
Avid Automobile Receivables Trust, Series 2018-1, 
 
 
 
Class A, 2.84%, 8/15/23 (144A) 
1,009,924 
6,935,780  
Avid Automobile Receivables Trust, Series 2019-1, 
 
 
 
Class A, 2.62%, 2/15/24 (144A) 
6,773,511 
1,266,667(b)  
Babson CLO, Ltd., Series 2015-IA, Class XR, 2.369% 
 
 
 
(3 Month USD LIBOR + 55 bps), 1/20/31 (144A) 
1,266,653 
150,000(b)  
Barings CLO, Ltd., Series 2018-2A, Class X, 2.431% 
 
 
 
(3 Month USD LIBOR + 60 bps), 4/15/30 (144A) 
149,999 
642,857(b)  
Barings CLO, Ltd., Series 2018-3A, Class X, 2.319% 
 
 
 
(3 Month USD LIBOR + 50 bps), 7/20/29 (144A) 
642,853 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 23

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
1,666,666(b)  
Barings CLO, Ltd., Series 2019-1A, Class X, 2.581% 
 
 
 
(3 Month USD LIBOR + 75 bps), 4/15/31 (144A) 
$ 1,666,656 
6,250,000(b)  
Barings Middle Market CLO, Ltd., Series 2018-IA, 
 
 
 
Class A1, 3.361% (3 Month USD LIBOR + 
 
 
 
153 bps), 1/15/31 (144A) 
5,842,269 
1,500,000(b)  
Battery Park CLO, Ltd., Series 2019-1A, Class X, 2.481% 
 
 
 
(3 Month USD LIBOR + 65 bps), 7/15/32 (144A) 
1,499,991 
519(c)  
Bayview Financial Acquisition Trust, Series 2007-A, 
 
 
 
Class 1A2, 6.205%, 5/28/37 
519 
10,274,301  
BCC Funding Corp. XVI LLC, Series 2019-1A, Class A1, 
 
 
 
2.3%, 10/20/20 (144A) 
10,228,244 
6,476,379  
BCC Funding XIV LLC, Series 2018-1A, Class A2, 2.96%, 
 
 
 
6/20/23 (144A) 
6,462,694 
2,500,000(b)  
BDS, Ltd., Series 2020-FL5, Class C, 2.662% (1 Month 
 
 
 
USD LIBOR + 205 bps), 2/16/37 (144A) 
2,020,665 
1,546,875(b)  
Bean Creek CLO, Ltd., Series 2015-1A, Class XR, 2.419% 
 
 
 
(3 Month USD LIBOR + 60 bps), 4/20/31 (144A) 
1,546,836 
257,997(b)  
Bear Stearns Asset Backed Securities I Trust, Series 
 
 
 
2005-TC1, Class M1, 1.607% (1 Month USD LIBOR 
 
 
 
+ 66 bps), 5/25/35 
255,501 
342,297(b)  
Bear Stearns Asset Backed Securities Trust, Series 2001-3, 
 
 
 
Class A1, 1.847% (1 Month USD LIBOR + 
 
 
 
90 bps), 10/27/32 
311,657 
565,343(b)  
Bear Stearns Asset Backed Securities Trust, Series 
 
 
 
2006-SD1, Class A, 1.317% (1 Month USD LIBOR + 
 
 
 
37 bps), 4/25/36 
563,027 
1,187,500(b)  
BlueMountain CLO, Ltd., Series 2013-2A, Class X, 2.452% 
 
 
 
(3 Month USD LIBOR + 65 bps), 10/22/30 (144A) 
1,187,417 
771,429(b)  
BlueMountain CLO, Ltd., Series 2018-2A, Class X, 2.342% 
 
 
 
(3 Month USD LIBOR + 65 bps), 8/15/31 (144A) 
771,422 
2,750,000(b)  
California Street CLO IX LP, Series 2012-9A, Class XR2, 
 
 
 
2.543% (3 Month USD LIBOR + 70 bps), 
 
 
 
7/16/32 (144A) 
2,749,725 
4,151,002(b)  
Canadian Pacer Auto Receivables Trust, Series 2018-2A, 
 
 
 
Class A2B, 0.93% (1 Month USD LIBOR + 
 
 
 
18 bps), 6/21/21 (144A) 
4,139,859 
850,000(b)  
Carlyle US CLO, Ltd., Series 2019-4A, Class M, 2.528% 
 
 
 
(3 Month USD LIBOR + 65 bps), 1/15/33 (144A) 
849,963 
2,366,276  
Carnow Auto Receivables Trust, Series 2018-1A, Class A, 
 
 
 
3.61%, 10/15/21 (144A) 
2,349,850 
12,211,385  
Carnow Auto Receivables Trust, Series 2019-1A, Class A, 
 
 
 
2.72%, 11/15/22 (144A) 
12,079,148 
3,000,000  
Carvana Auto Receivables Trust, Series 2019-4A, 
 
 
 
Class A2, 2.2%, 7/15/22 (144A) 
2,973,699 
8,000,000  
Carvana Auto Receivables Trust, Series 2020-N1A, 
 
 
 
Class B, 2.01%, 3/17/25 (144A) 
7,840,000 
5,000,000  
Carvana Auto Receivables Trust, Series 2020-N1A, 
 
 
 
Class D, 3.43%, 1/15/26 (144A) 
4,855,000 
 
The accompanying notes are an integral part of these financial statements.
24 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
466,645(b)  
Catamaran CLO, Ltd., Series 2013-1A, Class X, 2.344% 
 
 
 
(3 Month USD LIBOR + 55 bps), 1/27/28 (144A) 
$ 466,631 
866,949  
Cazenovia Creek Funding II LLC, Series 2018-1A, 
 
 
 
Class B, 3.984%, 7/15/30 (144A) 
821,483 
814,285(b)  
CBAM, Ltd., Series 2018-5A, Class X, 2.386% (3 Month 
 
 
 
USD LIBOR + 55 bps), 4/17/31 (144A) 
814,280 
2,062,500(b)  
Cent CLO 21, Ltd., Series 2014-21A, Class XR2, 2.444% 
 
 
 
(3 Month USD LIBOR + 65 bps), 7/27/30 (144A) 
2,062,483 
70,355(d)  
Centex Home Equity Loan Trust, Series 2003-A, Class AF6, 
 
 
 
3.654%, 3/25/33 
69,025 
281,250(b)  
CFIP CLO, Ltd., Series 2018-1A, Class X, 2.569% (3 Month 
 
 
 
USD LIBOR + 75 bps), 7/18/31 (144A) 
281,248 
778,346  
Chesapeake Funding II LLC, Series 2017-2A, Class A1, 
 
 
 
1.99%, 5/15/29 (144A) 
772,095 
1,704,578(b)  
Chesapeake Funding II LLC, Series 2017-2A, Class A2, 
 
 
 
1.155% (1 Month USD LIBOR + 45 bps), 
 
 
 
5/15/29 (144A) 
1,689,174 
2,769,675(b)  
Chesapeake Funding II LLC, Series 2017-3A, Class A2, 
 
 
 
1.045% (1 Month USD LIBOR + 34 bps), 
 
 
 
8/15/29 (144A) 
2,746,326 
3,850,787(b)  
Chesapeake Funding II LLC, Series 2018-1A, Class A2, 
 
 
 
1.155% (1 Month USD LIBOR + 45 bps), 
 
 
 
4/15/30 (144A) 
3,770,841 
1,125,000(b)  
CIFC Funding, Ltd., Series 2013-4A, Class XRR, 2.344% 
 
 
 
(3 Month USD LIBOR + 55 bps), 4/27/31 (144A) 
1,124,991 
2,142,857(b)  
CIFC Funding, Ltd., Series 2014-4RA, Class X, 2.386% 
 
 
 
(3 Month USD LIBOR + 55 bps), 10/17/30 (144A) 
2,142,844 
533,729  
CIG Auto Receivables Trust, Series 2017-1A, Class A, 
 
 
 
2.71%, 5/15/23 (144A) 
532,024 
7,746,368  
CIG Auto Receivables Trust, Series 2019-1A, Class A, 
 
 
 
3.33%, 8/15/24 (144A) 
7,643,567 
2,832,404(b)  
CIM Small Business Loan Trust, Series 2018-1A, Class A, 
 
 
 
2.173% (1 Month USD LIBOR + 140 bps), 
 
 
 
3/20/43 (144A) 
2,699,691 
1,824,420(b)  
Citigroup Mortgage Loan Trust, Inc., Series 2006-WFH1, 
 
 
 
Class M3, 1.547% (1 Month USD LIBOR + 
 
 
 
60 bps), 1/25/36 
1,803,972 
437,500(b)  
Clear Creek CLO, Series 2015-1A, Class X, 2.819% 
 
 
 
(3 Month USD LIBOR + 100 bps), 10/20/30 (144A) 
437,486 
1,750,000(b)  
Columbia Cent CLO 28, Ltd., Series 2018-28A, Class X, 
 
 
 
2.392% (3 Month USD LIBOR + 65 bps), 
 
 
 
11/7/30 (144A) 
1,749,984 
1,831,869  
Commonbond Student Loan Trust, Series 2016-B, 
 
 
 
Class A1, 2.73%, 10/25/40 (144A) 
1,858,435 
244,524(b)  
Commonbond Student Loan Trust, Series 2016-B, 
 
 
 
Class A2, 2.397% (1 Month USD LIBOR + 145 bps), 
 
 
 
10/25/40 (144A) 
242,025 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 25

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
  Asset Backed Securities — (continued) 
 
2,213,233(b)  
Commonbond Student Loan Trust, Series 2017-AGS, 
 
  
Class A2, 1.797% (1 Month USD LIBOR + 
 
  
85 bps), 5/25/41 (144A) 
$ 2,175,280 
4,597,111(b)  
Commonbond Student Loan Trust, Series 2017-BGS, 
 
  
Class A2, 1.597% (1 Month USD LIBOR + 
 
  
65 bps), 9/25/42 (144A) 
4,506,099 
3,738,609(b)  
Commonbond Student Loan Trust, Series 2018-AGS, 
 
  
Class A2, 1.447% (1 Month USD LIBOR + 
 
  
50 bps), 2/25/44 (144A) 
3,638,608 
7,865,714(b)  
Commonbond Student Loan Trust, Series 2018-BGS, 
 
  
Class A2, 1.517% (1 Month USD LIBOR + 
 
  
57 bps), 9/25/45 (144A) 
7,496,946 
6,090,104(b)  
Commonbond Student Loan Trust, Series 2018-CGS, 
 
  
Class A2, 1.747% (1 Month USD LIBOR + 
 
  
80 bps), 2/25/46 (144A) 
6,006,618 
8,591,168(b)  
Commonbond Student Loan Trust, Series 2019-AGS, 
 
  
Class A2, 1.847% (1 Month USD LIBOR + 
 
  
90 bps), 1/25/47 (144A) 
8,437,270 
749,674  
Conn’s Receivables Funding LLC, Series 2018-A, Class A, 
 
  
3.25%, 1/15/23 (144A) 
731,917 
508,560  
Conn’s Receivables Funding LLC, Series 2018-A, Class B, 
 
  
4.65%, 1/15/23 (144A) 
487,194 
1,663,916  
Conn’s Receivables Funding LLC, Series 2019-A, Class A, 
 
  
3.4%, 10/16/23 (144A) 
1,616,300 
5,200,000  
Conn’s Receivables Funding LLC, Series 2019-A, Class B, 
 
  
4.36%, 10/16/23 (144A) 
4,926,334 
9,216,102  
Conn’s Receivables Funding LLC, Series 2019-B, Class A, 
 
  
2.66%, 6/17/24 (144A) 
8,733,415 
106,647(b)  
Conseco Finance Home Equity Loan Trust, Series 2002-C, 
 
  
Class MV1, 2.205% (1 Month USD LIBOR +
 
  
150 bps), 5/15/32 
105,127 
3,603,615  
Consumer Lending Receivables Trust, Series 2019-A, 
 
  
Class A, 3.52%, 4/15/26 (144A) 
3,488,286 
24,991,948  
Consumer Loan Underlying Bond Club Certificate Issuer 
 
  
Trust, Series 2019-HP1, Class A, 2.59%, 
 
  
12/15/26 (144A) 
23,350,072 
14,651,165  
Consumer Loan Underlying Bond CLUB Credit Trust , 
 
  
Series 2020-P1, Class A, 2.26%, 3/15/28 (144A) 
14,050,126 
1,718,644  
Consumer Loan Underlying Bond Credit Trust, Series 
 
  
2018-P2, Class A, 3.47%, 10/15/25 (144A) 
1,695,093 
3,838,738  
Consumer Loan Underlying Bond Credit Trust, Series 
 
  
2019-P1, Class A, 2.94%, 7/15/26 (144A) 
3,707,875 
30,225(b)  
Countrywide Asset-Backed Certificates, Series 2004-8, 
 
  
Class M1, 1.997% (1 Month USD LIBOR + 
 
  
105 bps), 1/25/35 
30,177 
153,916(b)  
Countrywide Asset-Backed Certificates, Series 2005-9, 
 
  
Class M1, 1.467% (1 Month USD LIBOR + 
 
  
52 bps), 1/25/36 
151,814 
 
The accompanying notes are an integral part of these financial statements.
26 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
125,368(b)  
Countrywide Asset-Backed Certificates, Series 2005-BC1, 
 
 
 
Class M4, 1.847% (1 Month USD LIBOR + 
 
 
 
90 bps), 5/25/35 
$ 125,086 
231,718(b)  
Countrywide Asset-Backed Certificates, Series 2006-3, 
 
 
 
Class 2A3, 1.237% (1 Month USD LIBOR + 
 
 
 
29 bps), 6/25/36 
229,023 
3,760,525(b)  
Countrywide Asset-Backed Certificates, Series 2006-4, 
 
 
 
Class 2A3, 1.237% (1 Month USD LIBOR + 
 
 
 
29 bps), 7/25/36 
3,634,308 
195,984  
CPS Auto Receivables Trust, Series 2015-A, Class C, 
 
 
 
4.0%, 2/16/21 (144A) 
195,914 
742,448  
CPS Auto Receivables Trust, Series 2018-D, Class A, 
 
 
 
3.06%, 1/18/22 (144A) 
741,469 
5,000,000  
Credit Acceptance Auto Loan Trust , Series 2020-1A, 
 
 
 
Class C, 2.59%, 6/15/29 (144A) 
4,180,372 
1,280,505(b)  
Credit Suisse Seasoned Loan Trust, Series 2006-1, 
 
 
 
Class A, 1.187% (1 Month USD LIBOR + 
 
 
 
24 bps), 10/25/34 (144A) 
1,272,263 
153,870(b)  
Credit-Based Asset Servicing & Securitization LLC, Series 
 
 
 
2005-CB3, Class M2, 1.877% (1 Month USD LIBOR 
 
 
 
+ 93 bps), 5/25/35 
151,776 
1,061,239(b)  
CSFB Mortgage-Backed Pass-Through Certificates, Series 
 

 
2005-AGE1, Class M3, 1.597% (1 Month USD
 
 
 
LIBOR + 65 bps), 2/25/32 
1,054,287 
175,608(b)  
CWABS Asset-Backed Certificates Trust, Series 2005-17, 
 

 
Class 3AV2, 1.287% (1 Month USD LIBOR +
 
 
 
34 bps), 5/25/36 
173,743 
703,506(b)  
CWABS Asset-Backed Certificates Trust, Series 2005-AB1, 
 
 
 
Class M1, 1.577% (1 Month USD LIBOR + 
 
 
 
63 bps), 8/25/35 
696,890 
2,496,618(b)  
CWHEQ Revolving Home Equity Loan Resuritization Trust, 
 

 
Series 2006-RES, Class 4M1A, 0.985% (1 Month
 
 
 
USD LIBOR + 28 bps), 2/15/34 (144A) 
2,437,385 
3,018,082(b)  
CWHEQ Revolving Home Equity Loan Resuritization Trust, 
 

 
Series 2006-RES, Class 4N1A, 0.985% (1 Month
 
 
 
USD LIBOR + 28 bps), 2/15/34 (144A) 
2,933,096 
1,073,331(b)  
Deer Creek CLO, Ltd., Series 2017-1A, Class X, 2.819% 
 
 
 
(3 Month USD LIBOR + 100 bps), 10/20/30 (144A) 
1,073,310 
1,370,260  
Dell Equipment Finance Trust, Series 2018-2, Class A2, 
 
 
 
3.16%, 2/22/21 (144A) 
1,369,718 
195,000  
Dell Equipment Finance Trust, Series 2018-2, Class A3, 
 
 
 
3.37%, 10/22/23 (144A) 
195,907 
128  
Delta Funding Home Equity Loan Trust, Series 1997-2, 
 
 
 
Class A6, 7.04%, 6/25/27 
118 
3,681,666  
Diamond Resorts Owner Trust, Series 2016-1, Class B, 
 
 
 
3.37%, 11/20/28 (144A) 
3,656,866 
11,798,782  
DLL LLC, Series 2018-ST2, Class A3, 3.46%, 
 
 
 
1/20/22 (144A) 
11,815,918 


 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 27

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
6,277,164  
DLL LLC, Series 2019-MT3, Class A1, 2.062%, 
 
 
 
10/20/20 (144A) 
$ 6,255,582 
590,709(b)  
DRB Prime Student Loan Trust, Series 2015-D, Class A1, 
 
 
 
2.647% (1 Month USD LIBOR + 170 bps), 
 
 
 
1/25/40 (144A) 
 590,563 
386,141(b)  
DRB Prime Student Loan Trust, Series 2016-B, Class A1, 
 
 
 
2.747% (1 Month USD LIBOR + 180 bps), 
 
 
 
6/25/40 (144A) 
385,219 
352,735  
DRB Prime Student Loan Trust, Series 2016-B, Class A3, 
 
 
 
2.23%, 6/25/36 (144A) 
351,774 
1,808,312(b)  
DRB Prime Student Loan Trust, Series 2017-A, Class A1, 
 
 
 
1.797% (1 Month USD LIBOR + 85 bps), 
 
 
 
5/27/42 (144A) 
1,791,358 
15,785(b)  
Drive Auto Receivables Trust, Series 2019-2, Class A2B, 
 
 
 
0.985% (1 Month USD LIBOR + 28 bps), 3/15/22 
15,778 
2,978,048(b)  
Drug Royalty III LP 1, Series 2017-1A, Class A1, 4.331% 
 
 
 
(3 Month USD LIBOR + 250 bps), 4/15/27 (144A) 
2,956,362 
2,030,130(b)  
Drug Royalty III LP 1, Series 2018-1A, Class A1, 3.431% 
 
 
 
(3 Month USD LIBOR + 160 bps), 10/15/31 (144A) 
1,959,135 
1,500,000(b)  
Dryden 80 CLO, Ltd., Series 2019-80A, Class X, 2.784% 
 
 
 
(3 Month USD LIBOR + 90 bps), 1/17/33 (144A) 
1,499,893 
8,392,151  
DT Auto Owner Trust , Series 2020-1A, Class A, 1.94%, 
 
 
 
9/15/23 (144A) 
8,292,543 
322,087(b)  
Earnest Student Loan Program LLC, Series 2016-C, 
 
 
 
Class A1, 2.797% (1 Month USD LIBOR + 185 bps), 
 
 
 
10/27/36 (144A) 
322,854 
303,393(b)  
Earnest Student Loan Program LLC, Series 2016-D, 
 
 
 
Class A1, 2.347% (1 Month USD LIBOR + 
 
 
 
140 bps), 1/25/41 (144A) 
302,462 
994,182(b)  
Earnest Student Loan Program LLC, Series 2017-A, 
 
 
 
Class A1, 1.947% (1 Month USD LIBOR + 
 
 
 
100 bps), 1/25/41 (144A) 
985,048 
15,950,000(b)  
Elevation CLO, Ltd., Series 2015-4A, Class CR, 4.019% 
 
 
 
(3 Month USD LIBOR + 220 bps), 4/18/27 (144A) 
14,851,396 
2,000,000(b)  
Elmwood CLO IV, Ltd., Series 2020-1A, Class X, 0.0% 
 
 
 
(3 Month USD LIBOR + 70 bps), 4/15/33 (144A) 
1,859,998 
240,673  
Engs Commercial Finance Trust, Series 2016-1A, 
 
 
 
Class A2, 2.63%, 2/22/22 (144A) 
240,272 
36,728(b)  
EquiFirst Mortgage Loan Trust, Series 2004-2, Class M1, 
 
 
 
1.772% (1 Month USD LIBOR + 83 bps), 10/25/34 
36,672 
1,000,000(b)  
Evergreen Credit Card Trust, Series 2019-1, Class A, 
 
 
 
1.185% (1 Month USD LIBOR + 48 bps), 
 
 
 
1/15/23 (144A) 
948,632 
2,349,333  
FCI Funding LLC, Series 2019-1A, Class A, 3.63%, 
 
 
 
2/18/31 (144A) 
2,345,394 
21,345,954(d)  
Finance of America HECM Buyout , Series 2020-HB1, 
 
 
 
Class A, 2.012%, 2/25/30 (144A) 
21,597,494 
7,907,976(d)  
Finance of America Structured Securities Trust, Series 
 
 
 
2019-HB1, Class A, 3.279%, 4/25/29 (144A) 
7,851,468 
 
The accompanying notes are an integral part of these financial statements.
28 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
  Asset Backed Securities — (continued) 
 
1,331,000(d)  
Finance of America Structured Securities Trust, Series 
 
  
2019-HB1, Class M1, 3.396%, 4/25/29 (144A) 
$ 1,311,124 
42,081(b)  
First Franklin Mortgage Loan Trust, Series 2004-FF4, 
 
  
Class M1, 1.802% (1 Month USD LIBOR + 
 
  
86 bps), 6/25/34 
40,788 
208,114(b)  
First Franklin Mortgage Loan Trust, Series 2005-FFH2, 
 
  
Class M2, 1.757% (1 Month USD LIBOR + 
 
  
81 bps), 4/25/35 (144A) 
206,056 
3,839,182  
First Investors Auto Owner Trust, Series 2019-1A, 
 
  
Class A, 2.89%, 3/15/24 (144A) 
3,808,414 
27,000,000  
First Investors Auto Owner Trust, Series 2020-1A, 
 
  
Class A, 1.49%, 1/15/25 (144A) 
27,028,193 
6,510,000  
First Investors Auto Owner Trust, Series 2020-1A, 
 
  
Class B, 1.85%, 2/17/26 (144A) 
6,706,939 
9,000,000(b)  
First National Master Note Trust, Series 2017-2, 
 
  
Class A, 1.145% (1 Month USD LIBOR + 
 
  
44 bps), 10/16/23 
8,985,271 
301,871  
Flagship Credit Auto Trust, Series 2017-4, Class A, 
 
  
2.07%, 4/15/22 (144A) 
300,950 
12,975,000(b)  
Fort CRE LLC, Series 2018-1A, Class A1, 2.274% 
 
  
(1 Month USD LIBOR + 135 bps), 11/16/35 (144A) 
12,367,424 
2,750,000(b)  
Fortress Credit Opportunities IX CLO, Ltd., Series 2015-6A, 
 

 
Class A1TR, 3.194% (3 Month USD LIBOR +
  
136 bps), 7/10/30 (144A) 
2,574,539 
3,500,000(b)  
Fortress Credit Opportunities IX CLO, Ltd., Series 2017-9A, 
 
  
Class A1T, 3.242% (3 Month USD LIBOR + 
 
  
155 bps), 11/15/29 (144A) 
3,347,060 
8,762  
Foursight Capital Automobile Receivables Trust, Series 
 
  
2016-1, Class A2, 2.87%, 10/15/21 (144A) 
8,757 
1,056,882  
Foursight Capital Automobile Receivables Trust, Series 
 
  
2017-1, Class A, 2.37%, 4/15/22 (144A) 
1,053,965 
802,749  
Foursight Capital Automobile Receivables Trust, Series 
 
  
2018-2, Class A2, 3.32%, 4/15/22 (144A) 
800,998 
5,731,691  
Foursight Capital Automobile Receivables Trust, Series 
 
  
2019-1, Class A2, 2.58%, 3/15/23 (144A) 
5,704,366 
7,000,000  
Foursight Capital Automobile Receivables Trust, Series 
 
  
2020-1, Class A2, 1.97%, 9/15/23 (144A) 
6,869,421 
2,500,000  
Foursight Capital Automobile Receivables Trust, Series 
 
  
2020-1, Class B, 2.27%, 2/18/25 (144A) 
2,368,750 
7,237,649  
FREED ABS Trust, Series 2020-FP1, Class A, 2.52%, 
 
  
3/18/27 (144A) 
6,875,749 
2,771,839(b)  
Fremont Home Loan Trust, Series 2005-E, Class 1A1, 
 
  
1.177% (1 Month USD LIBOR + 23 bps), 1/25/36 
2,719,218 
6,100,131(b)  
Fremont Home Loan Trust, Series 2006-2, Class 1A1, 
 
  
1.107% (1 Month USD LIBOR + 16 bps), 2/25/36 
5,846,708 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 29

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
  Asset Backed Securities — (continued) 
 
1,206,802(b)  
GE-WMC Asset-Backed Pass-Through Certificates, 
 

 
Series 2005-2, Class A1, 1.172% (1 Month USD
 
  
LIBOR + 23 bps), 12/25/35 
$ 1,197,127 
3,407,667  
GLS Auto Receivables Issuer Trust, Series 2019-1A, 
 
  
Class A, 3.37%, 1/17/23 (144A) 
3,393,278 
8,850,415  
GLS Auto Receivables Issuer Trust, Series 2019-3A, 
 
  
Class A, 2.58%, 7/17/23 (144A) 
8,761,293 
3,000,000  
GLS Auto Receivables Issuer Trust, Series 2019-3A, 
 
  
Class B, 2.72%, 6/17/24 (144A) 
2,958,934 
7,946,996  
GLS Auto Receivables Issuer Trust, Series 2019-4A, 
 
  
Class A, 2.47%, 11/15/23 (144A) 
7,432,370 
800,000  
GLS Auto Receivables Trust, Series 2018-1A, Class B, 
 
  
3.52%, 8/15/23 (144A) 
756,898 
920,224  
GLS Auto Receivables Trust, Series 2018-2A, Class A, 
 
  
3.25%, 4/18/22 (144A) 
912,873 
2,361,265  
GLS Auto Receivables Trust, Series 2018-3A, Class A, 
 
  
3.35%, 8/15/22 (144A) 
2,347,085 
7,944,436(b)  
GM Financial Automobile Leasing Trust, Series 2019-3, 
 
  
Class A2B, 1.043% (1 Month USD LIBOR + 
 
  
27 bps), 10/20/21 
7,895,788 
3,595,499  
Gold Key Resorts LLC, Series 2014-A, Class B, 3.72%, 
 
  
3/17/31 (144A) 
3,593,295 
937,500(b)  
Goldentree Loan Management US CLO 3, Ltd., 
 
  
Series 2018-3A, Class X, 2.369% (3 Month USD LIBOR + 
 
  
55 bps), 4/20/30 (144A) 
937,493 
1,400,000(b)  
Goldentree Loan Management US CLO 5, Ltd., 
 
  
Series 2019-5A, Class X, 2.319% (3 Month USD LIBOR + 
 
  
50 bps), 10/20/32 (144A) 
1,399,992 
799,133(b)  
Golub Capital BDC CLO LLC, Series 2014-1A, Class A1R, 
 
  
2.744% (3 Month USD LIBOR + 95 bps), 
 
  
4/25/26 (144A) 
787,984 
3,000,000(b)  
Golub Capital Partners CLO 24M-R, Ltd., Series 2015-24A, 
 
  
Class AR, 3.341% (3 Month USD LIBOR + 
 
  
160 bps), 11/5/29 (144A) 
2,730,156 
1,821,000(b)  
Golub Capital Partners CLO 25M, Ltd., Series 2015-25A, 
 
  
Class AR, 3.121% (3 Month USD LIBOR + 
 
  
138 bps), 5/5/30 (144A) 
1,705,197 
10,000,000(b)  
Golub Capital Partners CLO 34M, Ltd., Series 2017-34A, 
 
  
Class AR, 3.441% (3 Month USD LIBOR + 
 
  
170 bps), 3/14/31 (144A) 
9,389,790 
5,000,000(b)  
Golub Capital Partners CLO 46M, Ltd., Series 2019-46A, 
 
  
Class A1A, 3.565% (3 Month USD LIBOR + 
 
  
180 bps), 4/20/32 (144A) 
4,662,510 
5,244,920  
Great American Auto Leasing, Inc., Series 2019-1, 
 
  
Class A2, 2.97%, 6/15/21 (144A) 
5,238,631 
2,350,000(b)  
Greywolf CLO III, Ltd., Series 2020-3RA, Class XR, 
 
  
2.302% (3 Month USD LIBOR + 50 bps), 
 
  
4/15/33 (144A) 
2,325,001 
 
The accompanying notes are an integral part of these financial statements.
30 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
1,174,056(b)  
GSAA Home Equity Trust, Series 2005-6, Class A3, 
 
 
 
1.317% (1 Month USD LIBOR + 37 bps), 6/25/35 
$ 1,169,031 
228,852(b)  
GSRPM Mortgage Loan Trust, Series 2006-1, Class A1, 
 
 
 
1.247% (1 Month USD LIBOR + 30 bps), 
 
 
 
3/25/35 (144A) 
225,336 
4,419,237(b)  
HANA SBA LOAN TRUST, Series 2019-1, Class A, 4.04% 
 
 
 
(1 Month USD LIBOR + 200 bps), 8/25/45 (144A) 
4,237,818 
1,000,000(b)  
Harbor Park CLO, Ltd., Series 2018-1A, Class X, 2.719% 
 
 
 
(3 Month USD LIBOR + 90 bps), 1/20/31 (144A) 
999,992 
237,442  
Hero Residual Funding, Series 2016-1R, Class A1, 4.5%, 
 
 
 
9/21/42 (144A) 
238,016 
1,176,773(b)  
Hertz Fleet Lease Funding LP, Series 2017-1, Class A1, 
 
 
 
1.513% (1 Month USD LIBOR + 65 bps), 
 
 
 
4/10/31 (144A) 
1,173,258 
4,865,886(b)  
Hertz Fleet Lease Funding LP, Series 2018-1, Class A1, 
 
 
 
1.363% (1 Month USD LIBOR + 50 bps), 
 
 
 
5/10/32 (144A) 
4,829,174 
388,250(b)  
Hertz Fleet Lease Funding LP, Series 2019-1, Class A1, 
 
 
 
1.333% (1 Month USD LIBOR + 47 bps), 
 
 
 
1/10/33 (144A) 
383,997 
45,777  
Hilton Grand Vacations Trust, Series 2014-AA, Class B, 
 
 
 
2.07%, 11/25/26 (144A) 
45,340 
4,000,000  
HOA Funding LLC, Series 2015-1A, Class B, 9.0%, 
 
 
 
8/20/44 (144A) 
3,909,450 
147,004(b)  
Home Equity Asset Trust, Series 2004-8, Class M1, 1.817% 
 
 
 
(1 Month USD LIBOR + 87 bps), 3/25/35 
145,222 
2,417,581(b)  
Home Equity Asset Trust, Series 2005-3, Class M4, 1.587% 
 
 
 
(1 Month USD LIBOR + 64 bps), 8/25/35 
2,374,407 
474,075(b)  
Home Equity Asset Trust, Series 2005-6, Class M2, 1.437% 
 
 
 
(1 Month USD LIBOR + 49 bps), 12/25/35 
472,628 
105,586(b)  
Home Equity Asset Trust, Series 2005-7, Class M1, 1.397% 
 
 
 
(1 Month USD LIBOR + 45 bps), 1/25/36 
102,254 
3,807,355(b)  
Home Equity Asset Trust, Series 2006-3, Class 2A4, 
 
 
 
1.257% (1 Month USD LIBOR + 31 bps), 7/25/36 
3,761,669 
2,000,000(b)  
Home Partners of America Trust, Series 2018-1, Class C, 
 
 
 
2.05% (1 Month USD LIBOR + 125 bps), 
 
 
 
7/17/37 (144A) 
1,775,649 
3,000,000(b)  
Home Partners of America Trust, Series 2017-1, Class C, 
 
 
 
2.35% (1 Month USD LIBOR + 155 bps), 
 
 
 
7/17/34 (144A) 
2,742,123 
2,500,000(b)  
Home Partners of America Trust, Series 2017-1, Class D, 
 
 
 
2.7% (1 Month USD LIBOR + 190 bps), 
 
 
 
7/17/34 (144A) 
2,250,266 
11,000,000  
HPEFS Equipment Trust, Series 2019-1A, Class A2, 2.19%, 
 
 
 
9/20/29 (144A) 
10,907,340 
1,097,931(b)  
HSI Asset Securitization Corp. Trust, Series 2006-OPT1, 
 
 
 
Class 2A4, 1.247% (1 Month USD LIBOR + 
 
 
 
30 bps), 12/25/35 
1,085,254 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 31

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
375,689(b)  
HSI Asset Securitization Corp. Trust, Series 2006-OPT2, 
 
 
 
Class M1, 1.317% (1 Month USD LIBOR + 
 
 
 
37 bps), 1/25/36 
$ 373,129 
2,067,000(b)  
Invitation Homes Trust, Series 2017-SFR2, Class C, 
 
 
 
2.25% (1 Month USD LIBOR + 145 bps), 
 
 
 
12/17/36 (144A) 
1,785,055 
11,250,311(b)  
Invitation Homes Trust, Series 2018-SFR1, Class A, 1.5% 
 
 
 
(1 Month USD LIBOR + 70 bps), 3/17/37 (144A) 
10,268,219 
4,000,000(b)  
Invitation Homes Trust, Series 2018-SFR1, Class B, 1.75% 
 
 
 
(1 Month USD LIBOR + 95 bps), 3/17/37 (144A) 
3,512,861 
7,165,000(b)  
Invitation Homes Trust, Series 2018-SFR1, Class D, 2.25% 
 
 
 
(1 Month USD LIBOR + 145 bps), 3/17/37 (144A) 
5,978,310 
5,479,251(b)  
Invitation Homes Trust, Series 2018-SFR1, Class E, 2.8% 
 
 
 
(1 Month USD LIBOR + 200 bps), 3/17/37 (144A) 
4,267,649 
1,750,000(b)  
Invitation Homes Trust, Series 2018-SFR2, Class C, 
 
 
 
1.985% (1 Month USD LIBOR + 128 bps), 
 
 
 
6/17/37 (144A) 
1,538,556 
10,000,000(b)  
Invitation Homes Trust, Series 2018-SFR2, Class D, 
 
 
 
2.155% (1 Month USD LIBOR + 145 bps), 
 
 
 
6/17/37 (144A) 
8,496,563 
6,856,743(b)  
Invitation Homes Trust, Series 2018-SFR3, Class E, 2.8% 
 
 
 
(1 Month USD LIBOR + 200 bps), 7/17/37 (144A) 
5,541,752 
13,821,000(b)  
Invitation Homes Trust, Series 2018-SFR4, Class E, 2.75% 
 
 
 
(1 Month USD LIBOR + 195 bps), 1/17/38 (144A) 
11,402,246 
5,900,000(b)  
Ivy Hill Middle Market Credit Fund X, Ltd., Series 10A, 
 
  
Class A1AR, 3.069% (3 Month USD LIBOR +
 
 
 
125 bps), 7/18/30 (144A) 
5,553,505 
214,286(b)  
Jefferson Mill CLO, Ltd., Series 2015-1I, Class XR, 
 
 
 
2.419% (3 Month USD LIBOR + 60 bps), 10/20/31 
214,274 
22,600,000  
Kabbage Funding LLC, Series 2019-1, Class A, 3.825%, 
 
 
 
3/15/24 (144A) 
21,978,520 
1,400,000  
Kabbage Funding LLC, Series 2019-1, Class C, 4.611%, 
 
 
 
3/15/24 (144A) 
1,354,661 
500,000(b)  
KVK CLO, Ltd., Series 2018-1A, Class A, 2.625% 
 
 
 
(3 Month USD LIBOR + 93 bps), 5/20/29 (144A) 
483,181 
15,000,000(b)  
KVK CLO, Ltd., Series 2018-1A, Class B, 3.345% (3 Month 
 
 
 
USD LIBOR + 165 bps), 5/20/29 (144A) 
13,712,520 
4,331,552(b)  
Laurel Road Prime Student Loan Trust, Series 2017-C, 
 
 
 
Class A1, 1.497% (1 Month USD LIBOR + 
 
 
 
55 bps), 11/25/42 (144A) 
4,266,148 
400,000(b)  
LCM 28, Ltd., Series 28A, Class X, 2.719% (3 Month USD 
 
 
 
LIBOR + 90 bps), 10/20/30 (144A) 
399,997 
814,233(b)  
Lehman XS Trust, Series 2005-4, Class 1A3, 1.747% 
 
 
 
(1 Month USD LIBOR + 80 bps), 10/25/35 
793,928 
9,291,048  
Lendingpoint Asset Securitization Trust, Series 2019-1, 
 
 
 
Class A, 3.154%, 8/15/25 (144A) 
9,108,402 
2,500,000  
Lendingpoint Asset Securitization Trust, Series 2019-1, 
 
 
 
Class B, 3.613%, 8/15/25 (144A) 
2,323,399 
 
The accompanying notes are an integral part of these financial statements.
32 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
  Asset Backed Securities — (continued) 
 
13,903,472  
Lendingpoint Asset Securitization Trust, Series 2020-1, 
 
  
Class A, 2.512%, 2/10/26 (144A) 
$ 13,095,119 
10,547,044  
LL ABS Trust, Series 2019-1A, Class A, 2.87%, 
 
  
3/15/27 (144A) 
10,145,964 
7,500,000(b)  
LoanCore Issuer, Ltd., Series 2019-CRE2, Class A, 1.835% 
 
  
(1 Month USD LIBOR + 113 bps), 5/15/36 (144A) 
7,020,810 
8,300,000(b)  
M360 LLC, Series 2019-CRE2, Class A, 2.105% 
 
  
(1 Month USD LIBOR + 140 bps), 9/15/34 (144A) 
7,661,364 
1,000,000(b)  
Madison Park Funding XII, Ltd., Series 2014-12A, 
 
  
Class CR, 4.169% (3 Month USD LIBOR + 
 
  
235 bps), 7/20/26 (144A) 
960,102 
3,714,494  
Marlette Funding Trust, Series 2017-1A, Class C, 6.658%, 
 
  
3/15/24 (144A) 
3,633,560 
1,236,102  
Marlette Funding Trust, Series 2018-3A, Class A, 3.2%, 
 
  
9/15/28 (144A) 
1,227,791 
9,177,089  
Marlette Funding Trust , Series 2020-1A, Class A, 2.24%, 
 
  
3/15/30 (144A) 
8,896,769 
22,614,401  
Marlin Receivables LLC, Series 2018-1A, Class A3, 3.36%, 
 
  
4/20/23 (144A) 
22,593,650 
15,500,000(b)  
Master Credit Card Trust, Series 2019-1A, Class A, 
 
  
1.404% (1 Month USD LIBOR + 48 bps), 
 
  
7/21/22 (144A) 
15,279,091 
9,300,000(b)  
Master Credit Card Trust II, Series 2018-3A, Class A, 
 
  
1.264% (1 Month USD LIBOR + 34 bps), 
 
  
1/21/22 (144A) 
9,248,379 
12,000,000(b)  
Master Credit Card Trust II, Series 2019-2A, Class A, 
 
  
1.314% (1 Month USD LIBOR + 39 bps), 
 
  
1/21/23 (144A) 
11,743,277 
300,567(b)  
Merrill Lynch Mortgage Investors Trust, Series 2004-OPT1, 
 
  
Class A1B, 1.807% (1 Month USD LIBOR + 
 
  
86 bps), 6/25/35 
287,668 
2,148,798(b)  
Merrill Lynch Mortgage Investors Trust, Series 2005-AR1, 
 
  
Class M1, 1.697% (1 Month USD LIBOR + 
 
  
75 bps), 6/25/36 
2,098,400 
5,726,310(c)  
MFA LLC, Series 2017-NPL1, Class A1, 3.352%, 
 
  
11/25/47 (144A) 
5,831,797 
5,750,000  
MMAF Equipment Finance LLC, Series 2019-B, Class A2, 
 
  
2.07%, 10/12/22 (144A) 
5,700,915 
4,500,000(b)  
Monroe Capital Mml CLO, Ltd., Series 2017-1A, Class A, 
 
  
3.402% (3 Month USD LIBOR + 160 bps), 
 
  
4/22/29 (144A) 
4,274,978 
1,848,563(b)  
Morgan Stanley Capital I, Inc. Trust, Series 2006-NC2, 
 
  
Class A2D, 1.237% (1 Month USD LIBOR + 
 
  
29 bps), 2/25/36 
1,694,722 
596,426(b)  
Morgan Stanley Home Equity Loan Trust, Series 2006-2, 
 
  
Class A4, 1.227% (1 Month USD LIBOR + 
 
  
28 bps), 2/25/36 
559,597 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 33

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
568,750(b)  
Motor Plc, Series 2017-1A, Class A1, 1.477% 
 
 
 
(1 Month USD LIBOR + 53 bps), 9/25/24 (144A) 
$ 567,120 
2,779,260(b)  
National Collegiate Trust, Series 2007-A, Class A, 
 
 
 
1.242% (1 Month USD LIBOR + 30 bps), 
 
 
 
5/25/31 (144A) 
2,615,574 
7,028,020(d)  
Nationstar HECM Loan Trust, Series 2019-1A, Class A, 
 
 
 
2.651%, 6/25/29 (144A) 
6,964,931 
7,062,270(b)  
Nationstar Home Equity Loan Trust, Series 2006-B, 
 
 
 
Class AV4, 1.227% (1 Month USD LIBOR + 
 
 
 
28 bps), 9/25/36 
6,806,262 
17,734,762(b)  
Navient Student Loan Trust, Series 2019-4A, Class A1, 
 
 
 
1.227% (1 Month USD LIBOR + 28 bps), 
 
 
 
7/25/68 (144A) 
17,499,145 
1,100,000(b)  
Navistar Financial Dealer Note Master Owner Trust II, 
 
 
 
Series 2018-1, Class C, 1.997% (1 Month USD LIBOR + 
 
 
 
105 bps), 9/25/23 (144A) 
1,064,463 
2,730,806  
Nelnet Private Education Loan Trust, Series 2016-A, 
 
 
 
Class A1B, 3.6%, 12/26/40 (144A) 
2,765,425 
8,881,595(b)  
Nelnet Student Loan Trust, Series 2005-2, Class A5, 
 
 
 
1.295% (3 Month USD LIBOR + 10 bps), 3/23/37 
8,346,387 
7,256,000(b)  
Neuberger Berman CLO XX, Ltd., Series 2015-20A, 
 
 
 
Class AR, 2.631% (3 Month USD LIBOR + 
 
 
 
80 bps), 1/15/28 (144A) 
6,955,290 
2,750,000(b)  
Neuberger Berman CLO XXII, Ltd., Series 2016-22A, 
 
 
 
Class XR, 2.736% (3 Month USD LIBOR + 
 
 
 
90 bps), 10/17/30 (144A) 
2,749,978 
969,619(b)  
New Century Home Equity Loan Trust, Series 2005-2, 
 
 
 
Class M2, 1.622% (1 Month USD LIBOR + 
 
 
 
68 bps), 6/25/35 
966,739 
820,093(b)  
Newtek Small Business Loan Trust, Series 2016-1A, 
 
 
 
Class A, 3.947% (1 Month USD LIBOR + 
 
 
 
300 bps), 2/25/42 (144A) 
809,487 
4,299,906(b)  
Newtek Small Business Loan Trust, Series 2017-1, 
 
 
 
Class A, 2.947% (1 Month USD LIBOR + 
 
 
 
200 bps), 2/15/43 (144A) 
4,140,296 
5,031,929(b)  
Newtek Small Business Loan Trust, Series 2018-1, 
 
 
 
Class A, 2.647% (1 Month USD LIBOR + 
 
 
 
170 bps), 2/25/44 (144A) 
4,856,739 
3,870,715(b)  
Newtek Small Business Loan Trust, Series 2018-1, 
 
 
 
Class B, 3.947% (1 Month USD LIBOR + 
 
 
 
300 bps), 2/25/44 (144A) 
3,752,000 
12,135,684(b)  
Newtek Small Business Loan Trust, Series 2019-1, 
 
  
Class A, 2.35% (PRIME + 90 bps), 12/25/44
 
 
 
(144A) 
11,702,108 
2,588,946(b)  
Newtek Small Business Loan Trust, Series 2019-1, 
 
 
 
Class B, 3.447% (1 Month USD LIBOR + 
 
 
 
250 bps), 12/25/44 (144A) 
2,497,547 
 
The accompanying notes are an integral part of these financial statements.
34 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
18,300,000(b)  
NextGear Floorplan Master Owner Trust, Series 2019-2A, 
 
 
 
Class A1, 1.405% (1 Month USD LIBOR + 
 
 
 
70 bps), 10/15/24 (144A) 
$ 16,693,802 
19,500,000(b)  
NextGear Floorplan Master Owner Trust, Series 2020-1A, 
 
 
 
Class A1, 2.056% (1 Month USD LIBOR + 
 
 
 
80 bps), 2/18/25 (144A) 
18,739,874 
12,554,270  
NMEF Funding 2015-A LLC, Series 2019-A, Class A, 
 
 
 
2.73%, 8/17/26 (144A) 
12,437,292 
159,286(b)  
NovaStar Mortgage Funding Trust, Series 2003-1, 
 
 
 
Class A2, 1.727% (1 Month USD LIBOR + 
 
 
 
78 bps), 5/25/33 
147,281 
1,500,000(b)  
Octagon Investment Partners XVI, Ltd., Series 2013-1A, 
 
 
 
Class XR, 2.386% (3 Month USD LIBOR + 
 
 
 
55 bps), 7/17/30 (144A) 
1,499,955 
3,375,000(b)  
Octagon Investment Partners XXI, Ltd., Series 2014-1A, 
 
 
 
Class XRR, 2.454% (3 Month USD LIBOR + 
 
 
 
75 bps), 2/14/31 (144A) 
3,374,605 
3,656,250(b)  
Octagon Investment Partners XXII, Ltd., Series 2014-1A, 
 
 
 
Class XRR, 2.452% (3 Month USD LIBOR + 
 
 
 
65 bps), 1/22/30 (144A) 
3,656,148 
8,500,000  
Ocwen Master Advance Receivables Trust, Series 2019-T1, 
 
 
 
Class AT1, 2.514%, 8/15/50 (144A) 
8,475,659 
1,250,000  
Ocwen Master Advance Receivables Trust, Series 2019-T1, 
 
 
 
Class DT1, 3.107%, 8/15/50 (144A) 
1,242,596 
2,250,000(b)  
OHA Credit Funding 3, Ltd., Series 2019-3A, Class X, 
 
 
 
2.469% (3 Month USD LIBOR + 65 bps), 
 
 
 
7/20/32 (144A) 
2,249,984 
2,750,000(b)  
OHA Credit Funding 5, Ltd., Series 2020-5A, Class X, 
 
 
 
1.856% (3 Month USD LIBOR + 55 bps), 
 
 
 
4/18/33 (144A) 
2,747,195 
4,070,663(b)  
OneMain Financial Issuance Trust, Series 2017-1A, 
 
 
 
Class A2, 1.505% (1 Month USD LIBOR + 
 
 
 
80 bps), 9/14/32 (144A) 
3,971,988 
1,475,000  
OneMain Financial Issuance Trust, Series 2019-1A, 
 
 
 
Class A, 3.48%, 2/14/31 (144A) 
1,386,991 
170,000  
OneMain Financial Issuance Trust, Series 2019-1A, 
 
 
 
Class B, 3.79%, 2/14/31 (144A) 
153,421 
6,046,099(b)  
Option One Mortgage Loan Trust, Series 2005-3, Class M2, 
 
 
 
1.682% (1 Month USD LIBOR + 74 bps), 8/25/35 
5,876,555 
1,807,578(b)  
Option One Mortgage Loan Trust, Series 2005-4, Class M1, 
 
 
 
1.387% (1 Month USD LIBOR + 44 bps), 11/25/35 
1,778,705 
2,830(c)  
Option One Mortgage Loan Trust, Series 2007-FXD2, 
 
 
 
Class 2A1, 5.9%, 3/25/37 
2,232 
12,950,000(b)  
Orec, Ltd., Series 2018-CRE1, Class A, 1.885% (1 Month 
 
 
 
USD LIBOR + 118 bps), 6/15/36 (144A) 
11,848,186 
1,624,382  
Oscar US Funding Trust IX LLC, Series 2018-2A, 
 
 
 
Class A2A, 3.15%, 8/10/21 (144A) 
1,627,275 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 35

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
13,500,000(b)  
Owl Rock CLO II, Ltd., Series 2019-2A, Class A1L, 
 
 
 
3.636% (3 Month USD LIBOR + 175 bps), 
 
 
 
1/20/31 (144A) 
$ 12,849,948 
30,861  
Oxford Finance Funding LLC, Series 2016-1A, Class A, 
 
 
3.968%, 6/17/24 (144A) 
30,786 
1,750,000(b)  
OZLM VIII, Ltd., Series 2014-8A, Class XRR, 2.536% 
 
 
 
(3 Month USD LIBOR + 70 bps), 10/17/29 (144A) 
1,749,988 
500,000(b)  
OZLM XXII, Ltd., Series 2018-22A, Class X, 2.386% 
 
 
 
(3 Month USD LIBOR + 55 bps), 1/17/31 (144A) 
499,966 
4,250,000(b)  
Palmer Square Loan Funding, Ltd., Series 2018-1A, 
 
 
 
Class A2, 2.881% (3 Month USD LIBOR + 
 
 
 
105 bps), 4/15/26 (144A) 
3,867,054 
1,000,000(b)  
Palmer Square Loan Funding, Ltd., Series 2018-2A, 
 
 
 
Class D, 5.781% (3 Month USD LIBOR + 
 
 
 
395 bps), 7/15/26 (144A) 
645,823 
1,611,035(b)  
PARTS Student Loan Trust , Series 2007-CT1, Class A, 
 
 
2.1% (3 Month USD LIBOR + 19 bps), 
 
 
 
2/25/33 (144A) 
1,530,703 
817,128  
Pawnee Equipment Receivables LLC, Series 2019-1, 
 
 
 
Class A1, 2.294%, 10/15/20 (144A) 
813,488 
10,000,000  
Pawnee Equipment Receivables LLC, Series 2019-1, 
 
 
 
Class A2, 2.29%, 10/15/24 (144A) 
9,864,494 
30,000,000(b)  
PFS Financing Corp., Series 2019-B, Class A, 1.255% 
 
 
(1 Month USD LIBOR + 55 bps), 9/15/23 (144A) 
28,863,237 
84,547(b)  
Popular ABS Mortgage Pass-Through Trust, Series 2005-A, 
 
 
Class M1, 1.377% (1 Month USD LIBOR + 
 
 
 
43 bps), 6/25/35 
84,051 
996,459  
Prosper Marketplace Issuance Trust, Series 2019-1A, 
 
 
Class A, 3.54%, 4/15/25 (144A) 
985,896 
5,067,403  
Prosper Marketplace Issuance Trust, Series 2019-4A, 
 
 
Class A, 2.48%, 2/17/26 (144A) 
4,813,967 
8,200,000  
Purchasing Power Funding LLC, Series 2018-A, Class A, 
 
 
3.34%, 8/15/22 (144A) 
8,176,590 
2,600,000  
Purchasing Power Funding LLC, Series 2018-A, Class B, 
 
 
3.58%, 8/15/22 (144A) 
2,592,345 
7,020,075(b)  
RAAC Trust, Series 2006-RP1, Class M2, 2.147% (1 Month 
 
 
USD LIBOR + 120 bps), 10/25/45 (144A) 
6,703,511 
686,273(b)  
RAMP Trust, Series 2005-EFC6, Class M2, 1.592% (1 Month 
 
 
USD LIBOR + 65 bps), 11/25/35 
669,225 
75,017(b)  
RAMP Trust, Series 2006-EFC2, Class A3, 1.107% (1 Month 
 
 
USD LIBOR + 16 bps), 12/25/36 
74,433 
13,382(b)  
RAMP Trust, Series 2006-RZ3, Class A3, 1.237% (1 Month 
 
 
USD LIBOR + 29 bps), 8/25/36 
13,284 
3,390,261(b)  
RAMP Trust, Series 2006-RZ4, Class A3, 1.217% (1 Month 
 
 
USD LIBOR + 27 bps), 10/25/36 
3,255,806 
771,529(b)  
RASC Trust, Series 2005-EMX4, Class M2, 1.607% (1 Month 
 
 
USD LIBOR + 66 bps), 11/25/35 
763,866 
 
The accompanying notes are an integral part of these financial statements.
36 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
1,209,145(b)  
RASC Trust, Series 2005-KS1, Class M1, 1.622% 
 
 
 
(1 Month USD LIBOR + 68 bps), 2/25/35 
$ 1,176,007 
645,584(b)  
RASC Trust, Series 2005-KS7, Class M4, 1.817% 
 
 
 
(1 Month USD LIBOR + 87 bps), 8/25/35 
640,789��
613,638(b)  
RASC Trust, Series 2005-KS8, Class M3, 1.427% 
 
 
 
(1 Month USD LIBOR + 48 bps), 8/25/35 
608,288 
121,100(b)  
RASC Trust, Series 2005-KS11, Class M1, 1.347% 
 
 
 
(1 Month USD LIBOR + 40 bps), 12/25/35 
120,594 
1,591,224(b)  
Ready Capital Mortgage Financing LLC, Series 2018-FL2, 
 
 
 
Class A, 1.797% (1 Month USD LIBOR + 
 
 
 
85 bps), 6/25/35 (144A) 
1,584,228 
10,970,901(b)  
ReadyCap Lending Small Business Loan Trust, 
 
 
 
Series 2019-2, Class A, 2.75% (PRIME + 50 bps), 
 
 
 
12/27/44 (144A) 
9,739,855 
6,400,000  
Republic FInance Issuance Trust, Series 2019-A, Class A, 
 
 
 
3.43%, 11/22/27 (144A) 
5,579,985 
2,433,173(d)  
RMF Buyout Issuance Trust, Series 2018-1, Class A, 
 
 
 
3.436%, 11/25/28 (144A) 
2,429,002 
2,000,000(d)  
RMF Buyout Issuance Trust, Series 2018-1, Class M1, 
 
 
 
3.912%, 11/25/28 (144A) 
1,989,020 
1,000,000(d)  
RMF Buyout Issuance Trust , Series 2019-1, Class M1, 
 
 
 
2.521%, 7/25/29 (144A) 
901,989 
7,500,000(b)  
Rosy, Series 2018-1, Class A2, 4.99% (1 Month USD LIBOR 
 
 
 
+ 325 bps), 12/15/25 (144A) 
7,125,000 
38,912(b)  
Salomon Mortgage Loan Trust, Series 2001-CB4, Class 1A1, 
 
 
 
1.847% (1 Month USD LIBOR + 90 bps), 11/25/33 
36,748 
2,856,937(b)  
Saxon Asset Securities Trust, Series 2006-2, Class A3C, 
 
 
 
1.097% (1 Month USD LIBOR + 15 bps), 9/25/36 
2,805,761 
560,936  
SCF Equipment Leasing LLC, Series 2017-1A, Class A, 
 
 
 
3.77%, 1/20/23 (144A) 
561,774 
2,726,913  
SCF Equipment Leasing LLC, Series 2017-2A, Class A, 
 
 
 
3.41%, 12/20/23 (144A) 
2,707,235 
9,509,446  
SCF Equipment Leasing LLC, Series 2019-1A, Class A1, 
 
 
 
3.04%, 3/20/23 (144A) 
9,459,614 
14,010,905  
SCF Equipment Leasing LLC, Series 2019-2A, Class A1, 
 
 
 
2.22%, 6/20/24 (144A) 
13,906,354 
20,943(b)  
Securitized Asset Backed Receivables LLC Trust, Series 
 
 
 
2005-OP2, Class M1, 1.377% (1 Month USD LIBOR 
 
 
 
+ 43 bps), 10/25/35 
20,284 
2,594,644  
Securitized Term Auto Receivables Trust, Series 2019-1A, 
 
 
 
Class A2, 2.862%, 5/25/21 (144A) 
2,598,413 
633,539(b)  
Security National Mortgage Loan Trust, Series 2007-1A, 
 
 
 
Class 2A, 1.297% (1 Month USD LIBOR + 
 
 
 
35 bps), 4/25/37 (144A) 
618,562 
2,604,603(b)  
SG Mortgage Securities Trust, Series 2005-OPT1, 
 
 
 
Class M1, 1.377% (1 Month USD LIBOR + 
 
 
 
43 bps), 10/25/35 
2,545,992 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 37

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
8,295,186(b)  
SLM Private Credit Student Loan Trust, Series 2007-A, 
 
 
 
Class A4A, 0.981% (3 Month USD LIBOR + 
 
 
 
24 bps), 12/16/41 
$ 7,311,948 
14,000,000(b)  
SLM Student Loan Trust, Series 2006-10, Class A6, 
 
 
 
1.944% (3 Month USD LIBOR + 15 bps), 3/25/44 
12,448,554 
7,492,856  
Small Business Lending Trust, Series 2019-A, Class A, 
 
 
 
2.85%, 7/15/26 (144A) 
7,342,998 
10,828,716  
Small Business Lending Trust, Series 2020-A, Class A, 
 
 
 
2.62%, 12/15/26 (144A) 
10,549,727 
1,000,000  
Small Business Lending Trust, Series 2020-A, Class C, 
 
 
 
5.01%, 12/15/26 (144A) 
921,668 
4,300,000  
Sofi Consumer Loan Program Trust, Series 2018-1, 
 
 
 
Class B, 3.65%, 2/25/27 (144A) 
3,602,921 
9,220,571  
Sofi Consumer Loan Program LLC, Series 2016-1, Class A, 
 
 
 
3.26%, 8/25/25 (144A) 
8,918,188 
445,403  
Sofi Consumer Loan Program LLC, Series 2016-2, Class A, 
 
 
 
3.09%, 10/27/25 (144A) 
437,175 
200,119  
Sofi Consumer Loan Program LLC, Series 2016-3, Class A, 
 
 
 
3.05%, 12/26/25 (144A) 
198,187 
905,210  
Sofi Consumer Loan Program LLC, Series 2016-4, Class A, 
 
 
 
3.18%, 11/25/25 (144A) 
885,347 
2,621,620  
Sofi Consumer Loan Program LLC, Series 2017-1, Class A, 
 
 
 
3.28%, 1/26/26 (144A) 
2,574,413 
124,152  
Sofi Consumer Loan Program LLC, Series 2017-3, Class A, 
 
 
 
2.77%, 5/25/26 (144A) 
123,073 
4,434,307  
Sofi Consumer Loan Program Trust, Series 2019-1, 
 
 
 
Class A, 3.24%, 2/25/28 (144A) 
4,297,403 
2,186,156  
Sofi Consumer Loan Program Trust, Series 2019-2, 
 
 
 
Class A, 3.01%, 4/25/28 (144A) 
2,120,614 
694,232(b)  
Sofi Professional Loan Program LLC, Series 2015-B, 
 
 
 
Class A1, 1.997% (1 Month USD LIBOR + 
 
 
 
105 bps), 4/25/35 (144A) 
691,875 
766,143(b)  
Sofi Professional Loan Program LLC, Series 2015-C, 
 
 
 
Class A1, 1.997% (1 Month USD LIBOR + 
 
 
 
105 bps), 8/27/35 (144A) 
760,256 
1,313,140(b)  
Sofi Professional Loan Program LLC, Series 2015-D, 
 
 
 
Class A1, 2.447% (1 Month USD LIBOR + 
 
 
 
150 bps), 10/27/36 (144A) 
1,295,728 
1,330,753(b)  
Sofi Professional Loan Program LLC, Series 2016-A, 
 
 
 
Class A1, 2.697% (1 Month USD LIBOR + 
 
 
 
175 bps), 8/25/36 (144A) 
1,333,816 
961,022(b)  
Sofi Professional Loan Program LLC, Series 2016-B, 
 
 
 
Class A1, 2.147% (1 Month USD LIBOR + 
 
 
 
120 bps), 6/25/33 (144A) 
956,601 
2,644,988(b)  
Sofi Professional Loan Program LLC, Series 2016-C, 
 
 
 
Class A1, 2.047% (1 Month USD LIBOR + 
 
 
 
110 bps), 10/27/36 (144A) 
2,616,202 
 
The accompanying notes are an integral part of these financial statements.
38 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
689,035(b)  
Sofi Professional Loan Program LLC, Series 2016-D, 
 
 
 
Class A1, 1.897% (1 Month USD LIBOR + 
 
 
 
95 bps), 1/25/39 (144A) 
$ 685,701 
1,786,762(b)  
Sofi Professional Loan Program LLC, Series 2016-E, 
 
 
 
Class A1, 1.797% (1 Month USD LIBOR + 
 
 
 
85 bps), 7/25/39 (144A) 
1,769,040 
467,217(b)  
Sofi Professional Loan Program LLC, Series 2017-A, 
 
 
 
Class A1, 1.647% (1 Month USD LIBOR + 
 
 
 
70 bps), 3/26/40 (144A) 
446,832 
585,824(b)  
Sofi Professional Loan Program LLC, Series 2017-C, 
 
 
 
Class A1, 1.547% (1 Month USD LIBOR + 
 
 
 
60 bps), 7/25/40 (144A) 
567,583 
1,020,083(b)  
Sofi Professional Loan Program LLC, Series 2017-E, 
 
 
 
Class A1, 1.447% (1 Month USD LIBOR + 
 
 
 
50 bps), 11/26/40 (144A) 
1,007,961 
151,335  
Sofi Professional Loan Program LLC, Series 2017-F, 
 
 
 
Class A1FX, 2.05%, 1/25/41 (144A) 
151,170 
1,392,921(b)  
Sofi Professional Loan Program LLC, Series 2018-A, 
 
 
 
Class A1, 1.297% (1 Month USD LIBOR + 
 
 
 
35 bps), 2/25/42 (144A) 
1,373,654 
779,078  
Sofi Professional Loan Program LLC, Series 2018-A, 
 
 
 
Class A2A, 2.39%, 2/25/42 (144A) 
779,146 
8,485,522  
Sofi Professional Loan Program LLC, Series 2019-C, 
 
 
 
Class A1FX, 2.13%, 11/16/48 (144A) 
8,459,070 
3,522,734  
Sofi Professional Loan Program Trust, Series 2018-B, 
 
 
 
Class A1FX, 2.64%, 8/25/47 (144A) 
3,501,763 
2,000,000(b)  
Sound Point CLO XXV, Ltd., Series 2019-4A, Class X, 
 
 
 
2.481% (3 Month USD LIBOR + 65 bps), 
 
 
 
1/15/33 (144A) 
1,999,922 
18,500,000  
Springleaf Funding Trust, Series 2015-BA, Class A, 
 
 
 
3.48%, 5/15/28 (144A) 
17,922,965 
4,500,000(b)  
Starwood Waypoint Homes Trust, Series 2017-1, Class E, 
 
 
 
3.305% (1 Month USD LIBOR + 260 bps), 
 
 
 
1/17/35 (144A) 
4,217,003 
687,500(b)  
Stewart Park CLO, Ltd., Series 2015-1A, Class X, 2.431% 
 
 
 
(3 Month USD LIBOR + 60 bps), 1/15/30 (144A) 
687,494 
28,612(b)  
Structured Asset Investment Loan Trust, Series 2004-10, 
 
 
 
Class A7, 2.007% (1 Month USD LIBOR + 
 
 
 
106 bps), 11/25/34 
28,547 
176,249(b)  
Structured Asset Investment Loan Trust, Series 2005-HE1, 
 
 
 
Class M1, 1.417% (1 Month USD LIBOR + 
 
 
 
47 bps), 7/25/35 
174,755 
3,221,714(b)  
Structured Asset Investment Loan Trust, Series 2005-HE3, 
 
 
 
Class M1, 1.667% (1 Month USD LIBOR + 
 
 
 
72 bps), 9/25/35 
3,068,300 
90,035(b)  
Structured Asset Securities Corp. Mortgage Loan Trust, 
 
  
Series 2005-NC2, Class M4, 1.652% (1 Month
 
 
 
USD LIBOR + 71 bps), 5/25/35 
86,730 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 39

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
4,121,691(b)  
Structured Asset Securities Corp. Mortgage Loan Trust, 
 

 
Series 2006-OPT1, Class A1, 1.127% (1 Month
 
 
 
USD LIBOR + 18 bps), 4/25/36 
$ 3,835,956 
1,739,326(b)  
Structured Asset Securities Corp. Mortgage Loan Trust, 
 

 
Series 2007-TC1, Class A, 1.247% (1 Month USD
 
 
 
LIBOR + 30 bps), 4/25/31 (144A) 
1,690,891 
445,582(b)  
Structured Asset Securities Corp. Trust, Series 2005-AR1, 
 
 
 
Class M1, 1.377% (1 Month USD LIBOR + 
 
 
 
43 bps), 9/25/35 
443,500 
500,000(b)  
Symphony CLO XIX, Ltd., Series 2018-19A, Class X, 2.343% 
 
 
 
(3 Month USD LIBOR + 50 bps), 4/16/31 (144A) 
499,997 
1,535,967  
Tax Ease Funding LLC, Series 2016-1A, Class A, 3.131%, 
 
 
 
6/15/28 (144A) 
1,527,977 
538,001  
TCF Auto Receivables Owner Trust, Series 2016-PT1A, 
 
 
 
Class A, 1.93%, 6/15/22 (144A) 
534,192 
158,900(b)  
Terwin Mortgage Trust, Series 2006-1, Class 1A3, 1.327% 
 
 
 
(1 Month USD LIBOR + 38 bps), 1/25/37 (144A) 
158,615 
4,632,892(b)  
Terwin Mortgage Trust, Series 2006-3, Class 1A2, 1.177% 
 
 
 
(1 Month USD LIBOR + 23 bps), 4/25/37 (144A) 
4,494,548 
625,000(b)  
THL Credit Wind River CLO, Ltd., Series 2015-1A, 
 
 
 
Class X, 2.469% (3 Month USD LIBOR + 
 
 
 
65 bps), 10/20/30 (144A) 
621,898 
407,936  
Tidewater Auto Receivables Trust, Series 2018-AA, 
 
 
 
Class A2, 3.12%, 7/15/22 (144A) 
407,263 
31,182,000  
Tidewater Auto Receivables Trust, Series 2020-AA, 
 
 
 
Class A2, 1.39%, 8/15/24 (144A) 
30,187,753 
2,750,000  
Tidewater Auto Receivables Trust, Series 2020-AA, 
 
 
 
Class E, 3.35%, 7/17/28 (144A) 
2,467,630 
2,889,159  
TLF National Tax Lien Trust, Series 2017-1A, Class A, 
 
 
 
3.09%, 12/15/29 (144A) 
2,879,453 
13,359,594(b)  
Towd Point Asset Trust, Series 2018-SL1, Class A, 2.227% 
 
 
 
(1 Month USD LIBOR + 60 bps), 1/25/46 (144A) 
13,116,160 
11,000,000(b)  
Towd Point Asset Trust, Series 2018-SL1, Class B, 2.677% 
 
 
 
(1 Month USD LIBOR + 105 bps), 1/25/46 (144A) 
10,103,917 
528,932(d)  
Towd Point Mortgage Trust, Series 2015-4, Class A1, 
 
 
 
3.5%, 4/25/55 (144A) 
528,402 
2,541,076(d)  
Towd Point Mortgage Trust, Series 2015-5, Class A1B, 
 
 
 
2.75%, 5/25/55 (144A) 
2,520,233 
1,510,253(d)  
Towd Point Mortgage Trust, Series 2017-5, Class XA, 
 
 
 
3.5%, 2/25/57 (144A) 
1,501,838 
7,289,079(d)  
Towd Point Mortgage Trust, Series 2018-SJ1, Class XA, 
 
 
 
5.0%, 10/25/58 (144A) 
7,186,998 
4,785,536(d)  
Towd Point Mortgage Trust, Series 2019-HY2, Class XA, 
 
 
 
5.0%, 5/25/58 (144A) 
4,744,758 
5,318,000(b)  
Towd Point Mortgage Trust, Series 2019-HY3, Class A1B, 
 
 
 
1.947% (1 Month USD LIBOR + 100 bps), 
 
 
 
10/25/59 (144A) 
4,707,645 
 
The accompanying notes are an integral part of these financial statements.
40 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
12,289,656  
Towd Point Mortgage Trust, Series 2019-HY3, Class XA, 
 
 
 
4.5%, 10/25/59 (144A) 
$ 12,151,853 
15,908,289(d)  
Towd Point Mortgage Trust, Series 2019-SJ3, Class A1, 
 
 
 
3.0%, 11/25/59 (144A) 
15,780,224 
13,394,999(d)  
Towd Point Mortgage Trust, Series 2019-SJ3, Class XA, 
 
 
 
4.5%, 11/25/59 (144A) 
12,725,249 
8,000,000(b)  
Trafigura Securitisation Finance Plc, Series 2017-1A, 
 
 
 
Class A1, 1.555% (1 Month USD LIBOR + 
 
 
 
85 bps), 12/15/20 (144A) 
7,976,256 
2,000,000(b)  
Trafigura Securitisation Finance Plc, Series 2017-1A, 
 
 
 
Class B, 2.405% (1 Month USD LIBOR + 
 
 
 
170 bps), 12/15/20 (144A) 
1,987,760 
13,750,000(b)  
Trafigura Securitisation Finance Plc, Series 2018-1A, 
 
 
 
Class A1, 1.435% (1 Month USD LIBOR + 
 
 
 
73 bps), 3/15/22 (144A) 
13,693,914 
2,500,000  
Trafigura Securitisation Finance Plc, Series 2018-1A, 
 
 
 
Class B, 4.29%, 3/15/22 (144A) 
2,487,335 
2,423,077(b)  
Tralee CLO V, Ltd., Series 2018-5A, Class AX, 2.519% 
 
 
 
(3 Month USD LIBOR + 70 bps), 10/20/28 (144A) 
2,423,060 
16,400,000(b)  
TRTX Issuer, Ltd., Series 2019-FL3, Class C, 2.9% 
 
 
 
(1 Month USD LIBOR + 210 bps), 9/15/34 (144A) 
13,284,253 
12,000,000  
United Auto Credit Securitization Trust, Series 2018-1, 
 
 
 
Class E, 4.84%, 8/10/23 (144A) 
11,967,016 
8,680,000  
United Auto Credit Securitization Trust, Series 2019-1, 
 
 
 
Class B, 3.03%, 4/10/24 (144A) 
8,581,209 
1,372,427  
Upstart Pass-Through Trust, Series 2020-ST2, Class A, 
 
 
 
3.5%, 3/20/28 (144A) 
1,097,942 
4,650,000  
Upstart Pass-Through Trust, Series 2020-ST3, Class A, 
 
 
 
3.35%, 4/20/28 (144A) 
3,720,000 
437,571  
Upstart Securitization Trust, Series 2019-1, Class A, 
 
 
 
3.45%, 4/20/26 (144A) 
434,192 
12,228,863  
Upstart Securitization Trust, Series 2019-2, Class A, 
 
 
 
2.897%, 9/20/29 (144A) 
11,328,202 
17,328,174  
Upstart Securitization Trust, Series 2019-3, Class A, 
 
 
 
2.684%, 1/21/30 (144A) 
17,206,905 
27,000,000  
Upstart Securitization Trust, Series 2020-1, Class A, 
 
 
 
2.322%, 4/22/30 (144A) 
25,473,366 
9,338,087  
US Auto Funding LLC, Series 2019-1A, Class A, 3.61%, 
 
 
 
4/15/22 (144A) 
9,113,132 
184,211(b)  
Venture 32 CLO, Ltd., Series 2018-32RR, Class AX, 2.569% 
 
 
 
(3 Month USD LIBOR + 75 bps), 7/19/31 (144A) 
184,209 
1,396,838(b)  
Venture XXI CLO, Ltd., Series 2015-21A, Class AR, 2.711% 
 
 
 
(3 Month USD LIBOR + 88 bps), 7/15/27 (144A) 
1,331,464 
2,293,979(b)  
Verizon Owner Trust, Series 2017-3A, Class A1B, 1.043% 
 
 
 
(1 Month USD LIBOR + 27 bps), 4/20/22 (144A) 
2,284,919 
10,000,000(b)  
Verizon Owner Trust, Series 2019-A, Class A1B, 1.103% 
 
 
 
(1 Month USD LIBOR + 33 bps), 9/20/23 
9,830,997 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 41

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Asset Backed Securities — (continued) 
 
23,500,000(b)  
Verizon Owner Trust, Series 2019-C, Class A1B, 1.193% 
 
 
 
(1 Month USD LIBOR + 42 bps), 4/22/24 
$ 22,398,931 
27,000,000(b)  
Verizon Owner Trust, Series 2020-A, Class A1B, 1.043% 
 
 
 
(1 Month USD LIBOR + 27 bps), 7/22/24 
25,699,667 
2,260,460  
Veros Automobile Receivables Trust, Series 2018-1, 
 
 
 
Class A, 3.63%, 5/15/23 (144A) 
2,256,195 
26,000,000  
Veros Automobile Receivables Trust, Series 2020-1, 
 
 
 
Class A, 1.67%, 9/15/23 (144A) 
25,609,654 
2,000,000  
Veros Automobile Receivables Trust, Series 2020-1, 
 
 
 
Class B, 2.19%, 6/16/25 (144A) 
1,924,520 
6,500,000  
Volvo Financial Equipment LLC, Series 2019-2A, Class A2, 
 
 
 
2.02%, 8/15/22 (144A) 
6,475,555 
11,250,000(b)  
Volvo Financial Equipment Master Owner Trust, 
 
 
 
Series 2018-A, Class A, 1.225% (1 Month USD LIBOR + 
 
 
 
52 bps), 7/17/23 (144A) 
11,120,142 
16,015(b)  
Wells Fargo Home Equity Asset-Backed Securities Trust, 
 

 
Series 2006-2, Class A4, 1.197% (1 Month USD
 
 
 
LIBOR + 25 bps), 7/25/36 
15,986 
127,586  
Westgate Resorts LLC, Series 2016-1A, Class A, 3.5%, 
 
 
 
12/20/28 (144A) 
126,912 
3,376,831  
Westgate Resorts LLC, Series 2017-1A, Class A, 3.05%, 
 
 
 
12/20/30 (144A) 
3,200,086 
1,582,889  
Westgate Resorts LLC, Series 2017-1A, Class B, 4.05%, 
 
 
 
12/20/30 (144A) 
1,488,516 
3,469,662  
Westgate Resorts LLC, Series 2018-1A, Class B, 3.58%, 
 
 
 
12/20/31 (144A) 
3,448,298 
537,932  
Westgate Resorts LLC, Series 2018-1A, Class C, 4.1%, 
 
 
 
12/20/31 (144A) 
534,422 
11,462  
Wheels SPV 2 LLC, Series 2017-1A, Class A2, 1.88%, 
 
 
 
4/20/26 (144A) 
11,451 
9,888(b)  
Wilshire Mortgage Loan Trust, Series 1997-2, Class A6, 
 
 
 
1.227% (1 Month USD LIBOR + 28 bps), 5/25/28 
9,527 
444,589  
World Omni Select Auto Trust, Series 2018-1A, Class A2, 
 
 
 
3.24%, 4/15/22 (144A) 
444,225 
 
 TOTAL ASSET BACKED SECURITIES 
 
 
 
(Cost $1,811,498,721) 
$1,746,889,150 
 
 COLLATERALIZED MORTGAGE OBLIGATIONS — 
 
 
 15.2% of Net Assets 
 
160,515(d)  
Agate Bay Mortgage Trust, Series 2014-3, Class A4, 
 
 
 
3.0%, 11/25/44 (144A) 
$ 159,608 
105,479(b)  
Alternative Loan Trust, Series 2004-6CB, Class A, 
 
 
 
1.527% (1 Month USD LIBOR + 58 bps), 5/25/34 
103,505 
3,435,445  
Amur Equipment Finance Receivables VII LLC, 
 
 
 
Series 2019-1A, Class A1, 2.45%, 7/20/20 (144A) 
3,432,108 
376,852(b)  
Bear Stearns ALT-A Trust, Series 2004-12, Class 1A2, 
 
 
 
1.787% (1 Month USD LIBOR + 84 bps), 1/25/35 
365,406 
 
The accompanying notes are an integral part of these financial statements.
42 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
665,945(b)  
Bear Stearns ALT-A Trust, Series 2004-12, Class 1A3, 
 
 
 
1.647% (1 Month USD LIBOR + 70 bps), 1/25/35 
$ 638,300 
328,498(b)  
Bear Stearns ALT-A Trust, Series 2004-12, Class 1A4, 
 
 
 
1.787% (1 Month USD LIBOR + 84 bps), 1/25/35 
314,713 
101,013(d)  
Bear Stearns Mortgage Securities, Inc., Series 1997-6, 
 
 
 
Class 3B1, 3.992%, 6/25/30 
98,135 
791,433(b)  
Bellemeade Re, Ltd., Series 2017-1, Class M1, 2.647% 
 
 
 
(1 Month USD LIBOR + 170 bps), 10/25/27 (144A) 
790,100 
4,200,000(b)  
Bellemeade Re, Ltd., Series 2017-1, Class M2, 4.297% 
 
 
 
(1 Month USD LIBOR + 335 bps), 10/25/27 (144A) 
3,652,789 
10,926,324(b)  
Bellemeade Re, Ltd., Series 2018-1A, Class M1B, 2.547% 
 
 
 
(1 Month USD LIBOR + 160 bps), 4/25/28 (144A) 
10,843,246 
3,943,258(b)  
Bellemeade Re, Ltd., Series 2018-3A, Class M1B, 2.797% 
 
 
 
(1 Month USD LIBOR + 185 bps), 10/25/28 (144A) 
3,919,884 
6,125,000(b)  
Bellemeade Re, Ltd., Series 2018-3A, Class M2, 3.697% 
 
 
 
(1 Month USD LIBOR + 275 bps), 10/25/28 (144A) 
4,561,950 
23,980(b)  
Bellemeade Re, Ltd., Series 2019-1A, Class M1A, 2.247% 
 
 
 
(1 Month USD LIBOR + 130 bps), 3/25/29 (144A) 
23,859 
5,140,000(b)  
Bellemeade Re, Ltd., Series 2019-1A, Class M1B, 2.697% 
 
 
 
(1 Month USD LIBOR + 175 bps), 3/25/29 (144A) 
4,528,948 
2,800,000(b)  
Bellemeade Re, Ltd., Series 2019-3A, Class B1, 3.447% 
 
 
 
(1 Month USD LIBOR + 250 bps), 7/25/29 (144A) 
1,981,972 
10,671,000(b)  
Bellemeade Re, Ltd., Series 2019-3A, Class M1B, 2.547% 
 
 
 
(1 Month USD LIBOR + 160 bps), 7/25/29 (144A) 
9,129,669 
10,150,000(b)  
Bellemeade Re, Ltd., Series 2019-4A, Class M1B, 2.947% 
 
 
 
(1 Month USD LIBOR + 200 bps), 10/25/29 (144A) 
9,693,063 
7,301,013(b)  
Brass NO 8 Plc, Series 8A, Class A1, 2.392% (3 Month 
 
 
 
USD LIBOR + 70 bps), 11/16/66 (144A) 
7,032,614 
88,052(b)  
CHL Mortgage Pass-Through Trust, Series 2003-15, 
 
 
 
Class 1A1, 1.447% (1 Month USD LIBOR + 
 
 
 
50 bps), 6/25/18 
88,052 
671  
Citicorp Mortgage Securities REMIC Pass-Through 
 

 
Certificates Trust, Series 2005-4, Class 2A1,
 
 
 
5.0%, 7/25/20 
656 
23,326,941(b)  
Connecticut Avenue Securities Trust, Series 2019-HRP1, 
 
 
 
Class M2, 3.811% (1 Month USD LIBOR + 
 
 
 
215 bps), 11/25/39 (144A) 
20,606,865 
17,682,347(b)  
Connecticut Avenue Securities Trust, Series 2019-R01, 
 

 
Class 2M2, 3.397% (1 Month USD LIBOR +
 
 
 
245 bps), 7/25/31 (144A) 
14,653,794 
5,491,954(b)  
Connecticut Avenue Securities Trust, Series 2020-R01, 
 

 
Class 1M1, 1.747% (1 Month USD LIBOR +
 
 
 
80 bps), 1/25/40 (144A) 
5,251,151 
877,428(b)  
Connecticut Avenue Securities Trust, Series 2020-R02, 
 

 
Class 2M1, 1.697% (1 Month USD LIBOR +
 
 
 
75 bps), 1/25/40 (144A) 
842,237 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 43

Schedule of Investments | 3/31/20 (continued)


    
Principal    
Amount    
USD ($)   Value 
  Collateralized Mortgage Obligations — (continued)  
69,956(b)  CSFB Mortgage-Backed Pass-Through Certificates, Series  

 2004-AR5, Class 11A2, 1.687% (1 Month USD 
  LIBOR + 74 bps), 6/25/34 $ 66,253 
236,835(d)  CSMC Trust, Series 2014-SAF1, Class A12, 4.0%,  
  3/25/44 (144A) 235,763 
5,160,204(b)  
Eagle Re, Ltd., Series 2018-1, Class M1, 2.647% 
 
 
 
(1 Month USD LIBOR + 170 bps), 11/25/28 (144A) 
5,135,938 
10,050,029(b)  
Eagle Re, Ltd., Series 2019-1, Class M1B, 2.747% 
 
 
 
(1 Month USD LIBOR + 180 bps), 4/25/29 (144A) 
10,004,725 
11,364,000(b)  
Eagle Re, Ltd., Series 2020-1, Class M1A, 1.847% 
 
 
 
(1 Month USD LIBOR + 90 bps), 1/25/30 (144A) 
10,835,165 
8,770,087(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2014-C02, Class 1M2, 3.547% (1 Month USD LIBOR + 
 
 
 
260 bps), 5/25/24 
7,868,826 
6,439,391(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2016-C02, Class 1M2, 6.947% (1 Month USD LIBOR + 
 
 
 
600 bps), 9/25/28 
6,283,458 
13,987,820(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2016-C03, Class 2M2, 6.847% (1 Month USD LIBOR + 
 
 
 
590 bps), 10/25/28 
13,638,115 
6,477,040(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2017-C01, Class 1M2, 4.497% (1 Month USD LIBOR + 
 
 
 
355 bps), 7/25/29 
5,925,252 
57,372(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2017-C02, Class 2M1, 2.097% (1 Month USD LIBOR + 
 
 
 
115 bps), 9/25/29 
57,102 
3,850,000(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2017-C02, Class 2M2, 4.597% (1 Month USD LIBOR + 
 
 
 
365 bps), 9/25/29 
2,778,813 
409,604(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2017-C04, Class 2M1, 1.797% (1 Month USD LIBOR + 
 
 
 
85 bps), 11/25/29 
405,849 
4,722,952(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2017-C05, Class 1M2, 3.147% (1 Month USD LIBOR + 
 
 
 
220 bps), 1/25/30 
4,173,099 
10,526,604(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2017-C05, Class 1M2B, 3.147% (1 Month USD LIBOR + 
 
 
 
220 bps), 1/25/30 
9,071,716 
8,871,668(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2017-C06, Class 2M2, 3.747% (1 Month USD LIBOR + 
 
 
 
280 bps), 2/25/30 
7,400,476 
3,940,785(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2017-C06, Class 2M2A, 3.747% (1 Month USD LIBOR + 
 
 
 
280 bps), 2/25/30 
3,757,892 
 
The accompanying notes are an integral part of these financial statements.
44 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
9,873,392(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2017-C07, Class 1M2A, 3.347% (1 Month USD LIBOR + 
 
 
 
240 bps), 5/25/30 
$ 9,246,175 
823,287(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2018-C03, Class 1M1, 1.627% (1 Month USD LIBOR + 
 
 
 
68 bps), 10/25/30 
809,032 
22,379,694(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2018-C04, Class 2M2, 3.497% (1 Month USD LIBOR + 
 
 
 
255 bps), 12/25/30 
18,343,948 
19,530,000(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2018-C05, Class 1M2, 3.297% (1 Month USD LIBOR + 
 
 
 
235 bps), 1/25/31 
16,401,358 
7,583,513(b)  
Fannie Mae Connecticut Avenue Securities, Series 
 
 
 
2018-C06, Class 1M2, 2.947% (1 Month USD LIBOR + 
 
 
 
200 bps), 3/25/31 
6,671,519 
307,909(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 
 

 
1695, Class EG, 2.709% (1 Month USD LIBOR +
 
 
105 bps), 3/15/24 
312,265 
161,016(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 
 
  
2106, Class F, 1.155% (1 Month USD LIBOR +
 
 
 
45 bps), 12/15/28 
160,564 
95,344(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 
 

 
2122, Class FD, 1.055% (1 Month USD LIBOR +
 
 
35 bps), 2/15/29 
94,908 
35,520(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 
 
  
2156, Class FQ, 1.055% (1 Month USD LIBOR +
 
 
 
35 bps), 5/15/29 
35,632 
186,109(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 
 

 
2186, Class FY, 1.305% (1 Month USD LIBOR +
 
 
60 bps), 4/15/28 
186,336 
39,090(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 
 
  
2368, Class AF, 1.655% (1 Month USD LIBOR +
 
 
 
95 bps), 10/15/31 
39,876 
43,062(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 
 

 
2377, Class FE, 1.305% (1 Month USD LIBOR +
 
 
60 bps), 11/15/31 
43,364 
114,569(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 
 
  
2411, Class FR, 1.305% (1 Month USD LIBOR +
 
 
 
60 bps), 6/15/31 
114,732 
80,038(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2432, 
 
 
 
Class FH, 1.405% (1 Month USD LIBOR + 
 
 
 
70 bps), 3/15/32 
78,955 
243,473(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2439, 
 
 
 
Class F, 1.705% (1 Month USD LIBOR + 
 
 
 
100 bps), 3/15/32 
247,622 
341,703(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2470, 
 
 
 
Class AF, 1.705% (1 Month USD LIBOR + 
 
 
 
100 bps), 3/15/32 
347,632 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 45

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
205,707(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2471, 
 
 
 
Class FD, 1.705% (1 Month USD LIBOR + 
 
 
 
100 bps), 3/15/32 
$ 209,212 
52,336(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2498, 
 
 
 
Class FQ, 1.305% (1 Month USD LIBOR + 
 
 
 
60 bps), 9/15/32 
52,709 
87,574(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2543, 
 
 
 
Class EF, 1.055% (1 Month USD LIBOR + 
 
 
 
35 bps), 12/15/32 
86,986 
393,851(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2551, 
 
 
 
Class FD, 1.105% (1 Month USD LIBOR + 
 
 
 
40 bps), 1/15/33 
391,574 
231,263(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2567, 
 
 
 
Class FJ, 1.105% (1 Month USD LIBOR + 
 
 
 
40 bps), 2/15/33 
229,873 
113,990(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2577, 
 
 
 
Class FA, 1.255% (1 Month USD LIBOR + 
 
 
 
55 bps), 2/15/33 
113,741 
9,211(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2585, 
 
 
 
Class FD, 1.205% (1 Month USD LIBOR + 
 
 
 
50 bps), 12/15/32 
9,193 
136,456(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2614, 
 
 
 
Class FV, 2.856% (1 Month USD LIBOR + 
 
 
 
150 bps), 5/15/33 
139,246 
186,581(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2631, 
 
 
 
Class FC, 1.105% (1 Month USD LIBOR + 
 
 
 
40 bps), 6/15/33 
185,472 
204(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2647, 
 
 
 
Class XF, 0.955% (1 Month USD LIBOR + 
 
 
 
25 bps), 7/15/21 
204 
115,255(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2711, 
 
 
 
Class FA, 1.705% (1 Month USD LIBOR + 
 
 
 
100 bps), 11/15/33 
118,112 
215,122(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2916, 
 
 
 
Class NF, 0.955% (1 Month USD LIBOR + 
 
 
 
25 bps), 1/15/35 
212,563 
368,494(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 2976, 
 
 
 
Class LF, 1.045% (1 Month USD LIBOR + 
 
 
 
34 bps), 5/15/35 
363,122 
192,732(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3012, 
 
 
 
Class FE, 0.955% (1 Month USD LIBOR + 
 
 
 
25 bps), 8/15/35 
191,882 
122,983(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3042, 
 
 
 
Class PF, 0.955% (1 Month USD LIBOR + 
 
 
 
25 bps), 8/15/35 
121,568 
69,656(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3067, 
 
 
 
Class FA, 1.055% (1 Month USD LIBOR + 
 
 
 
35 bps), 11/15/35 
68,670 
 
The accompanying notes are an integral part of these financial statements.
46 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
83,658(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3102, 
 
 
 
Class FG, 1.005% (1 Month USD LIBOR + 
 
 
 
30 bps), 1/15/36 
$ 82,550 
101,717(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3117, 
 
 
 
Class EF, 1.055% (1 Month USD LIBOR + 
 
 
 
35 bps), 2/15/36 
100,308 
327,097(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3117, 
 
 
 
Class FE, 1.005% (1 Month USD LIBOR + 
 
 
 
30 bps), 2/15/36 
321,810 
228,677(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3122, 
 
 
 
Class FP, 1.005% (1 Month USD LIBOR + 
 
 
 
30 bps), 3/15/36 
226,424 
144,332(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3147, 
 
 
 
Class PF, 1.005% (1 Month USD LIBOR + 
 
 
 
30 bps), 4/15/36 
143,260 
323,069(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3173, 
 
 
 
Class FC, 1.125% (1 Month USD LIBOR + 
 
 
 
42 bps), 6/15/36 
321,616 
720,295(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3175, 
 
 
 
Class FE, 1.015% (1 Month USD LIBOR + 
 
 
 
31 bps), 6/15/36 
720,676 
381,946(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3181, 
 
 
 
Class HF, 1.205% (1 Month USD LIBOR + 
 
 
 
50 bps), 7/15/36 
379,520 
18,226(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3191, 
 
 
 
Class FE, 1.105% (1 Month USD LIBOR + 
 
 
 
40 bps), 7/15/36 
18,119 
266,727(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3221, 
 
 
 
Class FW, 1.125% (1 Month USD LIBOR + 
 
 
 
42 bps), 9/15/36 
264,011 
78,135(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3222, 
 
 
 
Class FN, 1.105% (1 Month USD LIBOR + 
 
 
 
40 bps), 9/15/36 
77,545 
279,856(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3239, 
 
 
 
Class EF, 1.055% (1 Month USD LIBOR + 
 
 
 
35 bps), 11/15/36 
276,313 
148,648(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3239, 
 
 
 
Class FB, 1.055% (1 Month USD LIBOR + 
 
 
 
35 bps), 11/15/36 
146,794 
239,026(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3247, 
 
 
 
Class FA, 0.955% (1 Month USD LIBOR + 
 
 
 
25 bps), 8/15/36 
235,015 
632,014(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3266, 
 
 
 
Class F, 1.005% (1 Month USD LIBOR + 
 
 
 
30 bps), 1/15/37 
624,210 
207,866(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3307, 
 
 
 
Class FT, 0.945% (1 Month USD LIBOR + 
 
 
 
24 bps), 7/15/34 
203,848 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 47

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
34,022(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3315, 
 
 
 
Class F, 1.045% (1 Month USD LIBOR + 
 
 
 
34 bps), 5/15/37 
$ 33,592 
472,965(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3373, 
 
 
 
Class FB, 1.285% (1 Month USD LIBOR + 
 
 
 
58 bps), 10/15/37 
471,136 
85,436(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3376, 
 
 
 
Class FM, 1.325% (1 Month USD LIBOR + 
 
 
 
62 bps), 10/15/37 
85,266 
8,521  
Federal Home Loan Mortgage Corp. REMICS, Series 3455, 
 
 
 
Class BD, 4.5%, 6/15/23 
8,533 
22,936(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3560, 
 
 
 
Class FA, 1.955% (1 Month USD LIBOR + 
 
 
 
125 bps), 5/15/37 
22,981 
266,199(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3610, 
 
 
 
Class FA, 1.405% (1 Month USD LIBOR + 
 
 
 
70 bps), 12/15/39 
267,634 
101,051  
Federal Home Loan Mortgage Corp. REMICS, Series 3706, 
 
 
 
Class C, 2.0%, 8/15/20 
101,286 
152,695(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3708, 
 
 
 
Class PF, 1.055% (1 Month USD LIBOR + 
 
 
 
35 bps), 7/15/40 
151,291 
40,850  
Federal Home Loan Mortgage Corp. REMICS, Series 3760, 
 
 
 
Class KH, 2.0%, 11/15/20 
40,941 
67,170(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3767, 
 
 
 
Class JF, 1.005% (1 Month USD LIBOR + 
 
 
 
30 bps), 2/15/39 
67,137 
316,940  
Federal Home Loan Mortgage Corp. REMICS, Series 3778, 
 
 
 
Class D, 3.5%, 3/15/25 
318,046 
4,743(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3780, 
 
 
 
Class FE, 1.105% (1 Month USD LIBOR + 
 
 
 
40 bps), 12/15/20 
4,744 
95,421(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3784, 
 
 
 
Class F, 1.105% (1 Month USD LIBOR + 
 
 
 
40 bps), 7/15/23 
95,051 
24,869(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3792, 
 
 
 
Class DF, 1.105% (1 Month USD LIBOR + 
 
 
 
40 bps), 11/15/40 
24,882 
32,317(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3867, 
 
 
 
Class FD, 1.055% (1 Month USD LIBOR + 
 
 
 
35 bps), 5/15/41 
31,917 
101,829(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3914, 
 
 
 
Class LF, 0.905% (1 Month USD LIBOR + 
 
 
 
20 bps), 8/15/26 
101,441 
123,351(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3960, 
 
 
 
Class FB, 1.005% (1 Month USD LIBOR + 
 
 
 
30 bps), 2/15/30 
123,162 
 
The accompanying notes are an integral part of these financial statements.
48 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
219,774(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3970, 
 
 
 
Class GF, 1.005% (1 Month USD LIBOR + 
 
 
 
30 bps), 9/15/26 
$ 219,315 
448,349(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 3982, 
 
 
 
Class FL, 1.255% (1 Month USD LIBOR + 
 
 
 
55 bps), 12/15/39 
448,116 
174,432(b)  
Federal Home Loan Mortgage Corp. REMICS, Series 4056, 
 
 
 
Class QF, 1.055% (1 Month USD LIBOR + 
 
 
 
35 bps), 12/15/41 
173,119 
152,178(b)  
Federal Home Loan Mortgage Corp. Strips, Series 237, 
 
 
 
Class F14, 1.105% (1 Month USD LIBOR + 
 
 
 
40 bps), 5/15/36 
152,053 
132,206(b)  
Federal Home Loan Mortgage Corp. Strips, Series 239, 
 
 
 
Class F29, 0.955% (1 Month USD LIBOR + 
 
 
 
25 bps), 8/15/36 
132,004 
571,531(b)  
Federal Home Loan Mortgage Corp. Strips, Series 239, 
 
 
 
Class F30, 1.005% (1 Month USD LIBOR + 
 
 
 
30 bps), 8/15/36 
568,031 
170,638(b)  
Federal Home Loan Mortgage Corp. Strips, Series 244, 
 
 
 
Class F22, 1.055% (1 Month USD LIBOR + 
 
 
 
35 bps), 12/15/36 
171,006 
11,898(b)  
Federal National Mortgage Association REMICS, Series 
 
 
 
1991-124, Class FA, 1.847% (1 Month USD LIBOR 
 
 
 
+ 90 bps), 9/25/21 
11,944 
26,491(b)  
Federal National Mortgage Association REMICS, Series 
 
 
 
1993-230, Class FA, 2.227% (1 Month USD LIBOR 
 
 
 
+ 60 bps), 12/25/23 
26,303 
70,170(b)  
Federal National Mortgage Association REMICS, Series 
 
 
 
1993-247, Class FA, 2.436% (11th District 
 
 
 
Cost of Funds Index + 140 bps), 12/25/23 
71,185 
70,170(b)  
Federal National Mortgage Association REMICS, Series 
 
 
 
1993-247, Class FE, 1.947% (1 Month USD LIBOR 
 
 
 
+ 100 bps), 12/25/23 
70,584 
138,119(b)  
Federal National Mortgage Association REMICS, Series 
 
  
1994-40, Class FC, 1.447% (1 Month USD LIBOR
 
 
 
+ 50 bps), 3/25/24 
139,058 
19,088(b)  
Federal National Mortgage Association REMICS, Series 
 
  
1997-46, Class FA, 1.112% (1 Month USD LIBOR
 
 
 
+ 50 bps), 7/18/27 
19,249 
65,443(b)  
Federal National Mortgage Association REMICS, Series 
 
  
1998-21, Class F, 1.9% (1 Year CMT Index +
 
 
 
35 bps), 3/25/28 
65,675 
4,750(b)  
Federal National Mortgage Association REMICS, Series 
 
  
1999-49, Class FB, 1.447% (1 Month USD LIBOR
 
 
 
+ 50 bps), 3/25/23 
4,749 
38,081(b)  
Federal National Mortgage Association REMICS, Series 
 
  
2000-47, Class FD, 1.497% (1 Month USD LIBOR
 
 
 
+ 55 bps), 12/25/30 
38,073 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 49

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
155,733(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2001-35, Class F, 1.547% (1 Month USD LIBOR +
 
 
 
60 bps), 7/25/31 
$ 155,902 
62,868(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2001-37, Class F, 1.447% (1 Month USD LIBOR +
 
 
 
50 bps), 8/25/31 
63,064 
321,823(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2001-50, Class FQ, 1.547% (1 Month USD LIBOR
 
 
 
+ 60 bps), 11/25/31 
322,172 
141,602(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2001-65, Class F, 1.547% (1 Month USD LIBOR +
 
 
 
60 bps), 11/25/31 
141,756 
102,391(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2001-69, Class FA, 1.547% (1 Month USD LIBOR
 
 
 
+ 60 bps), 7/25/31 
102,578 
283,993(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2001-72, Class FB, 1.847% (1 Month USD LIBOR
 
 
 
+ 90 bps), 12/25/31 
287,522 
78,342(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2001-81, Class FL, 1.262% (1 Month USD LIBOR
 
 
 
+ 65 bps), 1/18/32 
78,574 
127,680(b)  
Federal National Mortgage Association REMICS, 
 
 
 
Series 2002-1, Class FC, 1.647% (1 Month USD LIBOR + 
 
 
 
70 bps), 1/25/32 
128,361 
410,545(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2002-13, Class FD, 1.847% (1 Month USD LIBOR
 
 
 
+ 90 bps), 3/25/32 
414,740 
278,852(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2002-34, Class FA, 1.112% (1 Month USD LIBOR
 
 
 
+ 50 bps), 5/18/32 
278,919 
201,794(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2002-56, Class FN, 1.947% (1 Month USD LIBOR
 
 
 
+ 100 bps), 7/25/32 
205,298 
28,374(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2002-58, Class FD, 1.547% (1 Month USD LIBOR
 
 
 
+ 60 bps), 8/25/32 
28,425 
131,914(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2002-77, Class F, 1.547% (1 Month USD LIBOR +
 
 
 
60 bps), 12/25/32 
132,153 
96,916(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2002-82, Class FB, 1.447% (1 Month USD LIBOR
 
 
 
+ 50 bps), 12/25/32 
96,740 
123,099(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2002-90, Class FH, 1.447% (1 Month USD LIBOR
 
 
 
+ 50 bps), 9/25/32 
122,882 
61,434(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2002-92, Class FB, 1.597% (1 Month USD LIBOR
 
 
 
+ 65 bps), 4/25/30 
61,507 
 
The accompanying notes are an integral part of these financial statements.
50 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
139,113(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2002-93, Class FH, 1.447% (1 Month USD LIBOR
 
 
 
+ 50 bps), 1/25/33 
$ 138,849 
113,554(b)  
Federal National Mortgage Association REMICS, 
 
 
 
Series 2003-7, Class FA, 1.697% (1 Month USD LIBOR + 
 
 
 
75 bps), 2/25/33 
114,380 
229,012(b)  
Federal National Mortgage Association REMICS, 
 
 
 
Series 2003-8, Class FJ, 1.297% (1 Month USD LIBOR + 
 
 
 
35 bps), 2/25/33 
228,581 
339,418(b)  
Federal National Mortgage Association REMICS, Series 
 
 
 
2003-31, Class FM, 1.447% (1 Month USD LIBOR 
 
 
 
+ 50 bps), 4/25/33 
338,755 
155,861(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2003-42, Class JF, 1.447% (1 Month USD LIBOR
 
 
 
+ 50 bps), 5/25/33 
155,195 
101,903(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2003-49, Class FY, 1.347% (1 Month USD LIBOR
 
 
 
+ 40 bps), 6/25/23 
101,830 
241,645(b)  
Federal National Mortgage Association REMICS, Series 
 
 
 
2003-107, Class FD, 1.447% (1 Month USD LIBOR 
 
 
 
+ 50 bps), 11/25/33 
240,451 
198,438(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2004-52, Class FW, 1.347% (1 Month USD LIBOR
 
 
 
+ 40 bps), 7/25/34 
196,593 
58,247(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2004-54, Class FN, 1.397% (1 Month USD LIBOR
 
 
 
+ 45 bps), 7/25/34 
57,561 
526,487(b)  
Federal National Mortgage Association REMICS, Series 
 
 
 
2004-79, Class FM, 1.247% (1 Month USD LIBOR 
 
 
 
+ 30 bps), 11/25/24 
525,609 
61,653(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2004-91, Class HF, 1.247% (1 Month USD LIBOR
 
 
 
+ 30 bps), 11/25/34 
61,618 
212,559(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2005-83, Class KT, 1.247% (1 Month USD LIBOR
 
 
 
+ 30 bps), 10/25/35 
209,376 
276,550(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2005-83, Class LF, 1.257% (1 Month USD LIBOR
 
 
 
+ 31 bps), 2/25/35 
275,055 
42,669(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2006-11, Class FB, 1.247% (1 Month USD LIBOR
 
 
 
+ 30 bps), 3/25/36 
42,107 
117,659(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2006-33, Class FH, 1.297% (1 Month USD LIBOR
 
 
 
+ 35 bps), 5/25/36 
116,490 
361,277(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2006-34, Class FA, 1.257% (1 Month USD LIBOR
 
 
 
+ 31 bps), 5/25/36 
356,836 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 51

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
255,004(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2006-42, Class CF, 1.397% (1 Month USD LIBOR
 
 
 
+ 45 bps), 6/25/36 
$ 252,643 
99,611(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2006-56, Class FC, 1.237% (1 Month USD LIBOR
 
 
 
+ 29 bps), 7/25/36 
98,314 
38,610(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2006-70, Class BF, 1.497% (1 Month USD LIBOR
 
 
 
+ 55 bps), 8/25/36 
38,543 
79,432(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2006-82, Class F, 1.517% (1 Month USD LIBOR +
 
 
 
57 bps), 9/25/36 
79,090 
121,607(b)  
Federal National Mortgage Association REMICS, Series 
 
 
 
2006-104, Class GF, 1.267% (1 Month USD LIBOR 
 
 
 
+ 32 bps), 11/25/36 
119,798 
45,769(b)  
Federal National Mortgage Association REMICS, Series 
 
 
 
2006-115, Class BF, 1.187% (1 Month USD LIBOR 
 
 
 
+ 24 bps), 12/25/36 
45,206 
147,152(b)  
Federal National Mortgage Association REMICS, 
 
 
 
Series 2007-2, Class FT, 1.197% (1 Month USD LIBOR + 
 
 
 
25 bps), 2/25/37 
144,432 
176,115(b)  
Federal National Mortgage Association REMICS, 
 
 
 
Series 2007-7, Class FJ, 1.147% (1 Month USD LIBOR + 
 
 
 
20 bps), 2/25/37 
173,627 
64,925(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2007-13, Class FA, 1.197% (1 Month USD LIBOR
 
 
 
+ 25 bps), 3/25/37 
63,938 
179,945(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2007-41, Class FA, 1.347% (1 Month USD LIBOR
 
 
 
+ 40 bps), 5/25/37 
178,621 
302,668(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2007-50, Class FN, 1.187% (1 Month USD LIBOR
 
 
 
+ 24 bps), 6/25/37 
296,672 
27,841(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2007-57, Class FA, 1.177% (1 Month USD LIBOR
 
 
 
+ 23 bps), 6/25/37 
27,371 
87,217(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2007-58, Class FA, 1.197% (1 Month USD LIBOR
 
 
 
+ 25 bps), 6/25/37 
86,187 
82,503(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2007-66, Class FB, 1.347% (1 Month USD LIBOR
 
 
 
+ 40 bps), 7/25/37 
81,461 
255,688(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2007-85, Class FG, 1.447% (1 Month USD LIBOR
 
 
 
+ 50 bps), 9/25/37 
253,894 
309,748(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2007-91, Class FB, 1.547% (1 Month USD LIBOR
 
 
 
+ 60 bps), 10/25/37 
308,805 
 
The accompanying notes are an integral part of these financial statements.
52 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
126,549(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2007-92, Class OF, 1.517% (1 Month USD LIBOR
 
 
 
+ 57 bps), 9/25/37 
$ 125,865 
70,787(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2007-93, Class FD, 1.497% (1 Month USD LIBOR
 
 
 
+ 55 bps), 9/25/37 
69,095 
31,538(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2007-98, Class FD, 1.397% (1 Month USD LIBOR
 
 
 
+ 45 bps), 6/25/37 
31,402 
42,932(b)  
Federal National Mortgage Association REMICS, Series 
 
 
 
2007-100, Class YF, 1.497% (1 Month USD LIBOR 
 
 
 
+ 55 bps), 10/25/37 
42,702 
52,788(b)  
Federal National Mortgage Association REMICS, Series 
 
 
 
2007-103, Class AF, 1.947% (1 Month USD LIBOR 
 
 
 
+ 100 bps), 3/25/37 
53,557 
55,024(b)  
Federal National Mortgage Association REMICS, Series 
 
 
 
2007-110, Class FA, 1.567% (1 Month USD LIBOR 
 
 
 
+ 62 bps), 12/25/37 
54,671 
43,831(b)  
Federal National Mortgage Association REMICS, 
 
 
 
Series 2008-6, Class FA, 1.647% (1 Month USD LIBOR + 
 
 
 
70 bps), 2/25/38 
44,059 
197,188(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2008-88, Class FA, 2.167% (1 Month USD LIBOR
 
 
 
+ 122 bps), 10/25/38 
199,880 
64,476(b)  
Federal National Mortgage Association REMICS, Series 
 
 
 
2009-113, Class FB, 1.497% (1 Month USD LIBOR 
 
 
 
+ 55 bps), 1/25/40 
64,455 
967  
Federal National Mortgage Association REMICS, Series 
 
 
 
2010-17, Class DE, 3.5%, 6/25/21 
967 
120,611(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2010-32, Class FD, 2.047% (1 Month USD LIBOR
 
 
 
+ 110 bps), 4/25/40 
122,185 
2,079(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2010-38, Class F, 1.247% (1 Month USD LIBOR +
 
 
 
30 bps), 4/25/25 
2,078 
75,938(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2010-43, Class FD, 1.547% (1 Month USD LIBOR
 
 
 
+ 60 bps), 5/25/40 
75,722 
121,890(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2010-43, Class IF, 1.447% (1 Month USD LIBOR
 
 
 
+ 50 bps), 5/25/40 
122,167 
15,097  
Federal National Mortgage Association REMICS, Series 
 
 
 
2010-112, Class AE, 2.0%, 10/25/25 
15,110 
214,464(b)  
Federal National Mortgage Association REMICS, Series 
 
 
 
2011-19, Class FM, 1.497% (1 Month USD LIBOR 
 
 
 
+ 55 bps), 5/25/40 
214,618 
196,123(b)  
Federal National Mortgage Association REMICS, Series 
 

 
2012-40, Class PF, 1.447% (1 Month USD LIBOR
 
 
 
+ 50 bps), 4/25/42 
194,369 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 53

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
1,566,889(b)  
Federal National Mortgage Association Trust, 
 

 
Series 2003-W6, Class F, 1.977% (1 Month USD
 
 
 
LIBOR + 35 bps), 9/25/42 
$ 1,546,167 
696,877(b)  
Federal National Mortgage Association Trust, 
 
 
 
Series 2005-W3, Class 2AF, 1.167% (1 Month USD 
 
 
 
LIBOR + 22 bps), 3/25/45 
694,199 
53,548(d)  
Federal National Mortgage Association Trust, 
 
 
 
Series 2005-W3, Class 3A, 4.083%, 4/25/45 
58,372 
85,375(d)  
Federal National Mortgage Association Trust, 
 
 
 
Series 2005-W4, Class 3A, 4.005%, 6/25/45 
91,644 
658,589(b)  
Federal National Mortgage Association Whole Loan, 
 
 
 
Series 2007-W1, Class 1AF1, 1.207% (1 Month USD 
 
 
 
LIBOR + 26 bps), 11/25/46 
648,867 
185,411(d)  
FirstKey Mortgage Trust, Series 2014-1, Class A2, 3.0%, 
 
 
 
11/25/44 (144A) 
184,838 
10,100,000(b)  
Freddie Mac Stacr Remic Trust, Series 2020-HQA2, 
 
 
 
Class M1, 1.911% (1 Month USD LIBOR + 
 
 
 
110 bps), 3/25/50 (144A) 
9,749,763 
8,470,000(b)  
Freddie Mac Stacr Remic Trust, Series 2020-HQA2, 
 
 
 
Class M2, 3.911% (1 Month USD LIBOR + 
 
 
 
310 bps), 3/25/50 (144A) 
5,450,304 
2,838,533(b)  
Freddie Mac Stacr Trust, Series 2018-HQA2, Class M1, 
 
 
 
1.697% (1 Month USD LIBOR + 75 bps), 
 
 
 
10/25/48 (144A) 
2,758,545 
14,300,000(b)  
Freddie Mac Stacr Trust, Series 2019-HRP1, Class M2, 
 
 
 
2.347% (1 Month USD LIBOR + 140 bps), 
 
 
 
2/25/49 (144A) 
12,028,315 
13,891,266(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2015-DNA3, Class M3, 5.647% (1 Month USD 
 
 
 
LIBOR + 470 bps), 4/25/28 
12,733,817 
1,104,314(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2015-HQA2, Class M2, 3.747% (1 Month USD 
 
 
 
LIBOR + 280 bps), 5/25/28 
1,092,229 
344,715(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2016-DNA1, Class M2, 3.847% (1 Month USD 
 
 
 
LIBOR + 290 bps), 7/25/28 
342,592 
17,450,000(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2016-DNA1, Class M3, 6.497% (1 Month USD 
 
 
 
LIBOR + 555 bps), 7/25/28 
16,795,609 
11,862,981(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2016-DNA2, Class M3, 5.597% (1 Month USD 
 
 
 
LIBOR + 465 bps), 10/25/28 
11,269,826 
17,304,709(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2016-DNA3, Class M3, 5.947% (1 Month USD 
 
 
 
LIBOR + 500 bps), 12/25/28 
16,437,648 
198,843(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2016-DNA4, Class M2, 2.247% (1 Month USD 
 
 
 
LIBOR + 130 bps), 3/25/29 
196,037 
 
The accompanying notes are an integral part of these financial statements.
54 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
14,967,126(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2016-DNA4, Class M3, 4.747% (1 Month USD 
 
 
 
LIBOR + 380 bps), 3/25/29 
$ 13,880,122 
1,750,759(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2016-HQA3, Class M2, 2.297% (1 Month USD 
 
 
 
LIBOR + 135 bps), 3/25/29 
1,677,073 
387,036(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2017-DNA1, Class M1, 2.147% (1 Month USD 
 
 
 
LIBOR + 120 bps), 7/25/29 
384,828 
1,400,000(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2017-DNA2, Class M2, 4.397% (1 Month USD 
 
 
 
LIBOR + 345 bps), 10/25/29 
1,245,868 
3,360,000(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2017-DNA3, Class M2, 3.447% (1 Month USD 
 
 
 
LIBOR + 250 bps), 3/25/30 
2,892,427 
17,483(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2017-HQA1, Class M1, 2.147% (1 Month USD 
 
 
 
LIBOR + 120 bps), 8/25/29 
17,401 
5,000,000(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2017-HQA1, Class M2, 4.497% (1 Month USD 
 
 
 
LIBOR + 355 bps), 8/25/29 
3,927,109 
214,857(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2017-HQA2, Class M1, 1.747% (1 Month USD 
 
 
 
LIBOR + 80 bps), 12/25/29 
212,212 
3,201,162(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2017-HQA2, Class M2, 3.597% (1 Month USD 
 
 
 
LIBOR + 265 bps), 12/25/29 
2,771,420 
9,410,954(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2017-HRP1, Class M2, 3.397% (1 Month USD 
 
 
 
LIBOR + 245 bps), 12/25/42 
8,733,838 
1,221,157(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2017-HRP1, Class M2D, 2.197% (1 Month USD 
 
 
 
LIBOR + 125 bps), 12/25/42 
1,088,656 
15,660,992(b)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2018-HQA1, Class M2, 3.247% (1 Month USD 
 
 
 
LIBOR + 230 bps), 9/25/30 
13,189,680 
4,617,062(d)  
Freddie Mac Structured Agency Credit Risk Debt Notes, 
 
 
 
Series 2018-SPI2, Class M1, 3.811%, 5/25/48 (144A) 
4,466,518 
352,458(d)  
Freddie Mac Whole Loan Securities Trust, Series 
 
 
 
2015-SC02, Class M1, 3.668%, 9/25/45 
351,284 
3,835,508(b)  
Gosforth Funding Plc, Series 2018-1A, Class A1, 2.129% 
 
 
 
(3 Month USD LIBOR + 45 bps), 8/25/60 (144A) 
3,750,267 
131,540(b)  
Government National Mortgage Association, Series 2003-7, 
 
 
 
Class FB, 0.905% (1 Month USD LIBOR + 
 
 
 
20 bps), 1/16/33 
130,945 
466,968(b)  
Government National Mortgage Association, Series 2005-3, 
 
 
 
Class FC, 0.955% (1 Month USD LIBOR + 
 
 
 
25 bps), 1/16/35 
461,641 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 55

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
437,751(b)  
Government National Mortgage Association, 
 

 
Series 2005-16, Class FA, 1.023% (1 Month USD
 
 
 
LIBOR + 25 bps), 2/20/35 
$ 429,821 
148,369(b)  
Government National Mortgage Association, 
 

 
Series 2008-69, Class FA, 1.273% (1 Month USD
 
 
 
LIBOR + 50 bps), 8/20/38 
147,627 
149,454(b)  
Government National Mortgage Association, Series 
 
 
 
2009-66, Class UF, 1.705% (1 Month USD LIBOR + 
 
 
 
100 bps), 8/16/39 
150,379 
658,123(b)  
Government National Mortgage Association, Series 
 
 
 
2009-88, Class MF, 1.373% (1 Month USD LIBOR + 
 
 
 
60 bps), 7/20/39 
658,264 
118,890(b)  
Government National Mortgage Association, Series 
 
 
 
2009-92, Class FJ, 1.385% (1 Month USD LIBOR + 
 
 
 
68 bps), 10/16/39 
118,778 
15,006(b)  
Government National Mortgage Association, Series 
 
 
 
2010-17, Class AF, 1.173% (1 Month USD LIBOR + 
 
 
 
40 bps), 10/20/38 
15,004 
152,517  
Government National Mortgage Association, Series 
 
 
 
2010-138, Class PE, 3.0%, 8/20/38 
154,016 
3,389,186(b)  
Holmes Master Issuer Plc, Series 2018-2A, Class A2, 
 
 
 
2.251% (3 Month USD LIBOR + 42 bps), 
 
 
 
10/15/54 (144A) 
3,374,029 
14,404,870(b)  
Home Partners of America Trust, Series 2017-1, Class A, 
 
 
 
1.617% (1 Month USD LIBOR + 82 bps), 
 
 
 
7/17/34 (144A) 
13,265,913 
7,200,000(b)  
Home Partners of America Trust, Series 2017-1, Class B, 
 
 
 
2.15% (1 Month USD LIBOR + 135 bps), 
 
 
 
7/17/34 (144A) 
6,696,419 
5,920,353(b)  
Home Re, Ltd., Series 2018-1, Class M1, 2.547% 
 
 
 
(1 Month USD LIBOR + 160 bps), 10/25/28 (144A) 
5,897,799 
8,726,260(b)  
Home Re, Ltd., Series 2019-1, Class M1, 2.597% 
 
 
 
(1 Month USD LIBOR + 165 bps), 5/25/29 (144A) 
8,683,146 
1,579,377(b)  
HomeBanc Mortgage Trust, Series 2005-3, Class A1, 
 
 
 
1.187% (1 Month USD LIBOR + 24 bps), 7/25/35 
1,540,688 
2,784,341(b)  
JP Morgan Mortgage Trust, Series 2018-7FRB, Class A3, 
 
 
 
2.377% (1 Month USD LIBOR + 75 bps), 
 
 
 
4/25/46 (144A) 
2,564,367 
8,432,054(d)  
JP Morgan Mortgage Trust, Series 2018-7FRB, Class B1, 
 
 
 
3.045%, 4/25/46 (144A) 
7,116,106 
7,975,237(d)  
JP Morgan Mortgage Trust, Series 2018-7FRB, Class B2, 
 
 
 
3.045%, 4/25/46 (144A) 
6,710,455 
1,978,568(b)  
JP Morgan Seasoned Mortgage Trust, Series 2014-1, 
 
 
 
Class AM, 1.447% (1 Month USD LIBOR + 
 
 
 
50 bps), 5/25/33 (144A) 
1,829,229 
4,992,729(d)  
JP Morgan Seasoned Mortgage Trust, Series 2014-1, 
 
 
 
Class B1, 2.473%, 5/25/33 (144A) 
4,647,912 
 
The accompanying notes are an integral part of these financial statements.
56 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
6,729,054(d)  
JP Morgan Seasoned Mortgage Trust, Series 2014-1, 
 
 
 
Class B2, 2.473%, 5/25/33 (144A) 
$ 6,264,320 
5,187,509(d)  
JP Morgan Seasoned Mortgage Trust, Series 2014-1, 
 
 
 
Class B3, 2.473%, 5/25/33 (144A) 
4,829,240 
541,282(b)  
JP Morgan Trust, Series 2015-1, Class 1A14, 3.083% 
 
 
 
(1 Month USD LIBOR + 125 bps), 12/25/44 (144A) 
481,252 
2,800,000(b)  
Lanark Master Issuer Plc, Series 2018-1A, Class 1A, 
 
 
 
2.103% (3 Month USD LIBOR + 42 bps), 
 
 
 
12/22/69 (144A) 
2,764,115 
813,450(b)  
LMREC, Inc., Series 2016-CRE2, Class A, 3.329% 
 
 
 
(1 Month USD LIBOR + 170 bps), 11/24/31 (144A) 
801,921 
23,102,465(b)  
LSTAR Securities Investment Trust, Series 2019-2, 
 
 
 
Class A1, 3.081% (1 Month USD LIBOR + 
 
 
 
150 bps), 4/1/24 (144A) 
22,200,616 
9,774,084(b)  
LSTAR Securities Investment, Ltd., Series 2019-3, 
 
 
 
Class A1, 3.081% (1 Month USD LIBOR + 
 
 
 
150 bps), 4/1/24 (144A) 
9,038,069 
26,986,377(b)  
LSTAR Securities Investment, Ltd., Series 2019-4, 
 
 
 
Class A1, 3.081% (1 Month USD LIBOR + 
 
 
 
150 bps), 5/1/24 (144A) 
25,324,051 
13,714,910(b)  
LSTAR Securities Investment, Ltd., Series 2019-5, 
 
 
 
Class A1, 3.081% (1 Month USD LIBOR + 
 
 
 
150 bps), 11/1/24 (144A) 
13,397,846 
13,050(d)  
Merrill Lynch Mortgage Investors Trust, Series 2003-G, 
 
 
 
Class A3, 3.565%, 1/25/29 
11,868 
678,826(b)  
Merrill Lynch Mortgage Investors Trust, Series 2003-H, 
 
 
 
Class A1, 1.587% (1 Month USD LIBOR + 
 
 
 
64 bps), 1/25/29 
619,127 
468,096(b)  
Merrill Lynch Mortgage Investors Trust, Series 2004-B, 
 
 
 
Class A2, 2.434% (6 Month USD LIBOR + 
 
 
 
54 bps), 5/25/29 
417,384 
32,025(b)  
Merrill Lynch Mortgage Investors Trust, Series 2004-C, 
 
 
 
Class A2B, 2.924% (6 Month USD LIBOR + 
 
 
 
100 bps), 7/25/29 
28,587 
104,834(d)  
Merrill Lynch Mortgage Investors Trust, Series 2004-D, 
 
 
 
Class A3, 3.646%, 9/25/29 
94,217 
146,756(b)  
Merrill Lynch Mortgage Investors Trust, Series 2004-G, 
 
 
 
Class A2, 2.524% (6 Month USD LIBOR + 
 
 
 
60 bps), 1/25/30 
130,844 
145,574(d)  
Mill City Mortgage Loan Trust, Series 2018-4, Class A1A, 
 
 
 
3.5%, 4/25/66 (144A) 
145,213 
4,338,467(d)  
Morgan Stanley Residential Mortgage Loan Trust, Series 
 
 
 
2014-1A, Class A1, 3.017%, 6/25/44 (144A) 
4,267,998 
6,000,000(b)  
Mortgage Insurance-Linked Notes Series , Series 2020-1, 
 
  
Class M1A, 1.897% (1 Month USD LIBOR +
 
 
 
95 bps), 2/25/30 (144A) 
5,752,394 
10,722,384(b)  
Oaktown Re II, Ltd., Series 2018-1A, Class M1, 2.497% 
 
 
 
(1 Month USD LIBOR + 155 bps), 7/25/28 (144A) 
10,666,020 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 57

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
3,620,000(b)  
Oaktown Re III, Ltd., Series 2019-1A, Class B1A, 
 
 
 
4.447% (1 Month USD LIBOR + 350 bps), 
 
 
 
7/25/29 (144A) 
$ 2,451,826 
13,573,000(b)  
Oaktown Re III, Ltd., Series 2019-1A, Class M1B, 
 
 
 
2.897% (1 Month USD LIBOR + 195 bps), 
 
 
 
7/25/29 (144A) 
12,150,722 
13,750,000(b)  
OBX Trust, Series 2019-EXP2, Class 2A1B, 1.847% 
 
 
 
(1 Month USD LIBOR + 90 bps), 6/25/59 (144A) 
12,076,103 
9,871,607(c)  
OSAT Trust, Series 2020-RPL1, Class A1, 3.072%, 
 
 
 
12/26/59 (144A) 
9,898,860 
7,950,000(b)  
Pepper I-Prime Trust, Series 2018-2A, Class A1U2, 
 
 
 
1.277% (1 Month USD LIBOR + 48 bps), 
 
 
 
10/13/20 (144A) 
7,955,347 
317,404(b)  
Pepper Residential Securities Trust No. 18, Series 18A, 
 

 
Class A1UA, 1.761% (1 Month USD LIBOR +
 
 
 
95 bps), 3/12/47 (144A) 
317,163 
2,824,866(b)  
Pepper Residential Securities Trust No. 21, Series 21A, 
 
 
 
Class A1U, 1.585% (1 Month USD LIBOR + 
 
 
 
88 bps), 1/16/60 (144A) 
2,794,683 
6,507,843(b)  
Pepper Residential Securities Trust No. 22, Series 22A, 
 
 
 
Class A1U, 1.773% (1 Month USD LIBOR + 
 
 
 
100 bps), 6/20/60 (144A) 
6,506,689 
10,956,410(b)  
Pepper Residential Securities Trust No. 25, Series 25A, 
 
 
 
Class A1U, 1.741% (1 Month USD LIBOR + 
 
 
 
93 bps), 3/12/61 (144A) 
10,853,595 
5,437,500  
Permanent Master Issuer Plc, Series 2018-1A, Class 1A1, 
 
 
 
2.211% (3 Month USD LIBOR + 38 bps), 
 
 
 
7/15/58 (144A) 
5,423,640 
4,530,468(b)  
Radnor Re, Ltd., Series 2018-1, Class M1, 2.347% 
 
 
 
(1 Month USD LIBOR + 140 bps), 3/25/28 (144A) 
4,520,371 
7,284,042(b)  
Radnor Re, Ltd., Series 2019-1, Class M1B, 2.897% 
 
 
 
(1 Month USD LIBOR + 195 bps), 2/25/29 (144A) 
7,257,791 
17,250,000(b)  
Radnor Re, Ltd., Series 2019-2, Class M1B, 2.697% 
 
 
 
(1 Month USD LIBOR + 175 bps), 6/25/29 (144A) 
16,136,785 
2,063,759(b)  
RESI Finance LP, Series 2003-CB1, Class B3, 2.313% 
 
 
 
(1 Month USD LIBOR + 145 bps), 6/10/35 (144A) 
1,859,756 
5,709,224(b)  
Resimac MBS Trust, Series 2018-2A, Class A1A, 1.713% 
 
 
 
(1 Month USD LIBOR + 85 bps), 4/10/50 (144A) 
5,693,353 
1,464,578(b)  
Resimac Premier, Series 2017-1A, Class A1A, 1.675% 
 
 
 
(1 Month USD LIBOR + 95 bps), 9/11/48 (144A) 
1,457,138 
2,667,773(b)  
Resimac Premier, Series 2018-1A, Class A1, 1.663% 
 
 
 
(1 Month USD LIBOR + 80 bps), 11/10/49 (144A) 
2,643,827 
11,321,420(b)  
Resimac Premier, Series 2019-2A, Class A1, 1.813% 
 
 
 
(1 Month USD LIBOR + 95 bps), 2/10/51 (144A) 
11,212,531 
10,118,469(d)  
RMF Buyout Issuance Trust, Series 2019-1, Class A, 
 
 
 
2.475%, 7/25/29 (144A) 
10,055,729 
4,500,000(d)  
RMF Buyout Issuance Trust, Series 2019-1, Class M2, 
 
 
 
2.872%, 7/25/29 (144A) 
4,296,960 
 
The accompanying notes are an integral part of these financial statements.
58 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Collateralized Mortgage Obligations — (continued) 
 
6,306,043(d)  
RMF Buyout Issuance Trust , Series 2020-1, Class A, 
 
 
 
2.158%, 2/25/30 (144A) 
$ 6,234,109 
2,000,000(d)  
RMF Buyout Issuance Trust , Series 2020-1, Class M1, 
 
 
 
2.332%, 2/25/30 (144A) 
1,913,500 
6,689,317(b)  
STACR Trust, Series 2018-HRP1, Class M2, 2.597% 
 
 
 
(1 Month USD LIBOR + 165 bps), 4/25/43 (144A) 
6,259,250 
194,444(b)  
STACR Trust, Series 2018-HRP1, Class M2A, 2.597% 
 
 
 
(1 Month USD LIBOR + 165 bps), 4/25/43 (144A) 
193,319 
6,238,600(b)  
STACR Trust, Series 2018-HRP2, Class M2, 2.197% 
 
 
 
(1 Month USD LIBOR + 125 bps), 2/25/47 (144A) 
5,915,053 
17,605,000(b)  
STACR Trust, Series 2018-HRP2, Class M3, 3.347% 
 
 
 
(1 Month USD LIBOR + 240 bps), 2/25/47 (144A) 
15,088,779 
7,247,796(b)  
STACR Trust , Series 2018-HRP1, Class B1, 4.697% 
 
 
 
(1 Month USD LIBOR + 375 bps), 4/25/43 (144A) 
4,462,914 
7,500,000(b)  
Starwood Waypoint Homes Trust, Series 2017-1, Class B, 
 
 
 
1.875% (1 Month USD LIBOR + 117 bps), 
 
 
 
1/17/35 (144A) 
6,917,233 
12,978,431(b)  
Towd Point HE Trust, Series 2019-HE1, Class A1, 1.847% 
 
 
 
(1 Month USD LIBOR + 90 bps), 4/25/48 (144A) 
12,589,069 
8,180,168(b)  
Towd Point HE Trust, Series 2019-HE1, Class M1, 2.047% 
 
 
 
(1 Month USD LIBOR + 110 bps), 4/25/48 (144A) 
7,903,099 
206,116(d)  
Verus Securitization Trust , Series 2018-1, Class A3, 
 
 
 
3.205%, 2/25/48 (144A) 
196,044 
 
 TOTAL COLLATERALIZED MORTGAGE OBLIGATIONS 
 
 
 
(Cost $870,064,354) 
$ 789,572,350
 
 COMMERCIAL MORTGAGE-BACKED 
 
 
 SECURITIES — 11.6% of Net Assets 
 
12,500,000(b)  
Austin Fairmont Hotel Trust, Series 2019-FAIR, Class E, 
 
 
 
2.955% (1 Month USD LIBOR + 225 bps), 
 
 
 
9/15/32 (144A) 
$ 9,788,552 
15,635,000(b)  
BAMLL Commercial Mortgage Securities Trust, Series 
 
 
 
2019-RLJ, Class C, 2.305% (1 Month USD LIBOR + 
 
 
 
160 bps), 4/15/36 (144A) 
12,142,000 
3,480,910(b)  
Bancorp Commercial Mortgage Trust, Series 2018-CRE4, 
 
 
 
Class A, 1.605% (1 Month USD LIBOR + 
 
 
 
90 bps), 9/15/35 (144A) 
3,022,345 
13,500,000(b)  
BHP Trust, Series 2019-BXHP, Class D, 2.476% (1 Month 
 
 
 
USD LIBOR + 177 bps), 8/15/36 (144A) 
10,986,220 
7,750,000(b)  
BTH-13 Mortgage Backed Securities Trust, Series 2018-13, 
 
 
 
Class A, 4.081% (1 Month USD LIBOR + 
 
 
 
250 bps), 8/18/21 (144A) 
7,727,042 
5,700,000(b)  
BTH-16 Mortgage-Backed Securities Trust, Series 2018-16, 
 
 
 
Class A, 4.081% (1 Month USD LIBOR + 
 
 
 
250 bps), 8/4/21 (144A) 
5,482,967 
5,700,000(b)  
BTH-20 Mortgage-Backed Securities Trust, Series 2018-20, 
 
 
 
Class A, 4.081% (1 Month USD LIBOR + 
 
 
 
250 bps), 9/24/20 (144A) 
5,650,683 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 59

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Commercial Mortgage-Backed Securities — (continued) 
 
7,625,000(b)  
BTH-21 Mortgage-Backed Securities Trust, Series 
 
 
 
2018-21, Class A, 4.081% (1 Month USD LIBOR + 
 
 
 
250 bps), 10/7/21 (144A) 
$ 7,582,657 
14,500,000(b)  
BTH-25 Mortgage-Backed Securities Trust, Series 
 
 
 
2019-25, Class A, 4.015% (1 Month USD LIBOR + 
 
 
 
250 bps), 2/18/21 (144A) 
14,337,909 
12,300,000(b)  
BTH-3 Mortgage-Backed Securities Trust, Series 2018-3, 
 
 
 
Class A, 4.081% (1 Month USD LIBOR + 
 
 
 
250 bps), 7/6/20 
11,985,878 
5,810,000(b)  
BX Commercial Mortgage Trust, Series 2018-IND, Class D, 
 
 
 
2.005% (1 Month USD LIBOR + 130 bps), 
 
 
 
11/15/35 (144A) 
5,329,763 
15,582,583(b)  
BX Commercial Mortgage Trust, Series 2019-XL, Class G, 
 
 
 
3.005% (1 Month USD LIBOR + 230 bps), 
 
 
 
10/15/36 (144A) 
13,086,333 
9,300,000(b)  
BX Trust, Series 2019-ATL, Class B, 2.091% (1 Month USD 
 
 
 
LIBOR + 139 bps), 10/15/36 (144A) 
7,466,758 
8,000,000(b)  
BXP Trust, Series 2017-CQHP, Class B, 1.805% (1 Month 
 
 
 
USD LIBOR + 110 bps), 11/15/34 (144A) 
6,680,403 
2,171,167(b)  
CG-CCRE Commercial Mortgage Trust, Series 2014-FL1, 
 
 
 
Class B, 1.855% (1 Month USD LIBOR + 
 
 
 
115 bps), 6/15/31 (144A) 
2,171,274 
722,572(b)  
CG-CCRE Commercial Mortgage Trust, Series 2014-FL2, 
 
 
 
Class A, 2.559% (1 Month USD LIBOR + 
 
 
 
185 bps), 11/15/31 (144A) 
687,413 
10,000,000(b)  
CGDB Commercial Mortgage Trust, Series 2019-MOB, 
 
 
 
Class C, 2.155% (1 Month USD LIBOR + 
 
 
 
145 bps), 11/15/36 (144A) 
8,273,669 
5,700,000(b)  
CGMS Commercial Mortgage Trust, Series 2017-MDRC, 
 
 
 
Class C, 2.005% (1 Month USD LIBOR + 
 
 
 
130 bps), 7/15/30 (144A) 
5,335,816 
14,935,551(b)  
CHC Commercial Mortgage Trust, Series 2019-CHC, 
 
 
 
Class C, 2.455% (1 Month USD LIBOR + 175 bps), 
 
 
 
6/15/34 (144A) 
14,169,798 
9,500,000(b)  
CHT Mortgage Trust, Series 2017-CSMO, Class C, 2.205% 
 
 
 
(1 Month USD LIBOR + 150 bps), 11/15/36 (144A) 
8,148,699 
8,750,000(b)  
Citigroup Commercial Mortgage Trust, Series 2019-SST2, 
 
 
 
Class B, 1.805% (1 Month USD LIBOR + 
 
 
 
110 bps), 12/15/36 (144A) 
8,344,739 
5,500,000(b)  
Citigroup Commercial Mortgage Trust, Series 2019-SST2, 
 
 
 
Class C, 2.005% (1 Month USD LIBOR + 
 
 
 
130 bps), 12/15/36 (144A) 
5,226,502 
15,000,000(b)  
CLNY Trust, Series 2019-IKPR, Class B, 2.183% (1 Month 
 
 
 
USD LIBOR + 148 bps), 11/15/38 (144A) 
12,676,538 
5,000,000(b)  
CLNY Trust, Series 2019-IKPR, Class E, 3.426% (1 Month 
 
 
 
USD LIBOR + 272 bps), 11/15/38 (144A) 
3,389,931 
 
The accompanying notes are an integral part of these financial statements.
60 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Commercial Mortgage-Backed Securities — (continued) 
 
6,750,000(b)  
Credit Suisse Commercial Mortgage Securities Corp., 
 
 
 
Series 2019-SKLZ, Class B, 2.605% (1 Month USD 
 
 
 
LIBOR + 190 bps), 1/15/34 (144A) 
$ 5,889,751 
10,000,000(b)  
Credit Suisse Mortgage Capital Certificates, Series 
 
 
 
2019-ICE4, Class E, 2.855% (1 Month USD LIBOR 
 
 
 
+ 215 bps), 5/15/36 (144A) 
8,397,714 
10,380,000(b)  
CSMC Trust, Series 2017-HD, Class B, 2.055% (1 Month 
 
 
 
USD LIBOR + 135 bps), 2/15/31 (144A) 
9,986,699 
19,750,000(b)  
Exantas Capital Corp., Series 2020-RSO8, Class A, 2.85% 
 
 
 
(1 Month USD LIBOR + 115 bps), 3/15/35 (144A) 
17,027,711 
5,042,070(b)  
FREMF Mortgage Trust, Series 2014-KF03, Class B, 
 
 
 
6.015% (1 Month USD LIBOR + 450 bps), 
 
 
 
1/25/21 (144A) 
4,961,737 
1,715,812(b)  
FREMF Mortgage Trust, Series 2014-KF05, Class B, 
 
 
 
5.515% (1 Month USD LIBOR + 400 bps), 
 
 
 
9/25/22 (144A) 
1,653,666 
2,930,828(b)  
FREMF Mortgage Trust, Series 2014-KS02, Class B, 
 
 
 
6.515% (1 Month USD LIBOR + 500 bps), 
 
 
 
8/25/23 (144A) 
2,865,732 
3,907,816(b)  
FREMF Mortgage Trust, Series 2018-KI01, Class B, 3.965% 
 
 
 
(1 Month USD LIBOR + 245 bps), 9/25/22 (144A) 
3,762,519 
5,009,151(b)  
GPMT, Ltd., Series 2018-FL1, Class A, 1.673% (1 Month 
 
 
 
USD LIBOR + 90 bps), 11/21/35 (144A) 
4,842,010 
3,250,000(b)  
GPMT, Ltd., Series 2018-FL1, Class AS, 1.973% (1 Month 
 
 
 
USD LIBOR + 120 bps), 11/21/35 (144A) 
3,125,911 
18,000,000(b)  
Great Wolf Trust, Series 2019-WOLF, Class D, 2.638% 
 
 
 
(1 Month USD LIBOR + 193 bps), 12/15/36 (144A) 
14,936,362 
9,400,000(d)  
GS Mortgage Securities Corp. Trust, Series 2016-RENT, 
 
 
 
Class E, 4.067%, 2/10/29 (144A) 
9,093,506 
3,500,000(b)  
GS Mortgage Securities Corp. Trust, Series 2017-STAY, 
 
 
 
Class B, 1.805% (1 Month USD LIBOR + 
 
 
 
110 bps), 7/15/32 (144A) 
3,130,866 
10,900,000(b)  
GS Mortgage Securities Corp. Trust, Series 2018-TWR, 
 
 
 
Class A, 1.605% (1 Month USD LIBOR + 
 
 
 
90 bps), 7/15/31 (144A) 
9,235,379 
11,000,000(b)  
GS Mortgage Securities Corp. Trust, Series 2019-70P, 
 
 
 
Class D, 2.455% (1 Month USD LIBOR + 
 
 
 
175 bps), 10/15/36 (144A) 
9,072,575 
7,400,000(b)  
GS Mortgage Securities Corp. Trust, Series 2019-SMP, 
 
 
 
Class D, 2.655% (1 Month USD LIBOR + 
 
 
 
195 bps), 8/15/32 (144A) 
5,685,345 
10,000,000(b)  
GS Mortgage Securities Corp. Trust, Series 2020-DUNE, 
 
 
 
Class A, 1.805% (1 Month USD LIBOR + 
 
 
 
110 bps), 12/15/36 (144A) 
8,110,090 
9,000,000(b)  
GS Mortgage Securities Corp. Trust, Series 2020-DUNE, 
 
 
 
Class E, 3.205% (1 Month USD LIBOR + 
 
 
 
250 bps), 12/15/36 (144A) 
6,959,524 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 61

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Commercial Mortgage-Backed Securities — (continued) 
 
4,300,000(b)  
GS Mortgage Securities Trust, Series 2018-HART, Class A, 
 
 
 
1.795% (1 Month USD LIBOR + 109 bps), 
 
 
 
10/15/31 (144A) 
$ 4,115,802 
9,729,000(b)  
GS Mortgage Securities Trust, Series 2018-HART, Class B, 
 
 
 
2.005% (1 Month USD LIBOR + 130 bps), 
 
 
 
10/15/31 (144A) 
9,284,876 
8,652,895(b)  
HPLY Trust, Series 2019-HIT, Class C, 2.305% (1 Month 
 
 
 
USD LIBOR + 160 bps), 11/15/36 (144A) 
6,710,929 
8,300,000(b)  
Hudsons Bay Simon JV Trust, Series 2015-HBFL, 
 
 
 
Class AFL, 3.498% (1 Month USD LIBOR + 183 bps), 
 
 
 
8/5/34 (144A) 
7,697,277 
8,665,000(b)  
InTown Hotel Portfolio Trust, Series 2018-STAY, Class A, 
 
 
 
1.405% (1 Month USD LIBOR + 70 bps), 
 
 
 
1/15/33 (144A) 
7,883,494 
4,230,000(b)  
InTown Hotel Portfolio Trust, Series 2018-STAY, Class B, 
 
 
 
1.755% (1 Month USD LIBOR + 105 bps), 
 
 
 
1/15/33 (144A) 
3,782,301 
2,078,000(d)  
JP Morgan Chase Commercial Mortgage Securities Trust, 
 
 
 
Series 2015-UES, Class C, 3.621%, 9/5/32 (144A) 
2,051,675 
11,900,000(b)  
JP Morgan Chase Commercial Mortgage Securities Trust, 
 
 
 
Series 2017-FL11, Class B, 1.805% (1 Month USD LIBOR 
 
 
 
+ 110 bps), 10/15/32 (144A) 
11,676,889 
7,300,000(b)  
JP Morgan Chase Commercial Mortgage Securities Trust, 
 
 
 
Series 2018-PHH, Class B, 1.865% (1 Month USD LIBOR 
 
 
 
+ 116 bps), 6/15/35 (144A) 
6,366,161 
2,800,000(b)  
JP Morgan Chase Commercial Mortgage Securities Trust, 
 
 
 
Series 2018-WPT, Class BFL, 2.627% (1 Month USD 
 
 
 
LIBOR + 125 bps), 7/5/33 (144A) 
2,548,633 
4,000,000(b)  
JP Morgan Chase Commercial Mortgage Securities Trust, 
 
 
 
Series 2018-WPT, Class CFL, 3.027% (1 Month USD 
 
 
 
LIBOR + 165 bps), 7/5/33 (144A) 
3,525,933 
3,600,000(b)  
JP Morgan Chase Commercial Mortgage Securities Trust, 
 
 
 
Series 2019-BKWD, Class C, 2.305% (1 Month USD LIBOR 
 
 
 
+ 160 bps), 9/15/29 (144A) 
3,306,243 
1,650,000(b)  
JP Morgan Chase Commercial Mortgage Securities Trust, 
 
 
 
Series 2019-BKWD, Class E, 3.305% (1 Month USD LIBOR 
 
 
 
+ 260 bps), 9/15/29 (144A) 
1,566,483 
10,300,000(b)  
JP Morgan Chase Commercial Mortgage Securities Trust, 
 
 
 
Series 2019-MFP, Class E, 2.865% (1 Month USD LIBOR 
 
 
 
+ 216 bps), 7/15/36 (144A) 
8,569,453 
194,615  
JPMBB Commercial Mortgage Securities Trust, Series 
 
 
 
2014-C19, Class A2, 3.046%, 4/15/47 
195,467 
18,050,000(b)  
MBRT, Series 2019-MBR, Class B, 1.855% (1 Month USD 
 
 
 
LIBOR + 115 bps), 11/15/36 (144A) 
15,437,181 
20,000,000(b)  
MF1, Ltd., Series 2019-FL2, Class A, 2.077% (1 Month 
 
 
 
USD LIBOR + 113 bps), 12/25/34 (144A) 
17,040,114 
10,313,648(b)  
MMFL Re-REMIC Trust, Series 2019-1, Class A, 2.347% 
 
 
 
(1 Month USD LIBOR + 140 bps), 1/28/24 (144A) 
9,950,362 
 
The accompanying notes are an integral part of these financial statements.
62 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Commercial Mortgage-Backed Securities — (continued) 
 
1,780,419(d)  
Morgan Stanley Capital I Trust, Series 2007-T25, 
 
 
 
Class AJ, 5.574%, 11/12/49 
$ 1,782,194 
8,500,000(b)  
Morgan Stanley Capital I Trust, Series 2017-ASHF, 
 
 
 
Class B, 1.955% (1 Month USD LIBOR + 
 
 
 
125 bps), 11/15/34 (144A) 
6,891,516 
8,250,000(b)  
Morgan Stanley Capital I Trust, Series 2017-CLS, 
 
 
 
Class C, 1.705% (1 Month USD LIBOR + 
 
 
 
100 bps), 11/15/34 (144A) 
7,741,199 
9,975,000(b)  
Morgan Stanley Capital I Trust, Series 2018-BOP, 
 
 
 
Class B, 1.955% (1 Month USD LIBOR + 
 
 
 
125 bps), 8/15/33 (144A) 
9,352,538 
9,280,000(b)  
Morgan Stanley Capital I Trust, Series 2019-AGLN, 
 
 
 
Class C, 2.155% (1 Month USD LIBOR + 
 
 
 
145 bps), 3/15/34 (144A) 
7,928,139 
7,275,000(b)  
Morgan Stanley Capital I Trust, Series 2019-NUGS, 
 
 
 
Class D, 3.3% (1 Month USD LIBOR + 
 
 
 
180 bps), 12/15/36 (144A) 
6,877,208 
14,300,000(b)  
Morgan Stanley Capital I Trust, Series 2019-PLND, 
 
 
 
Class C, 2.205% (1 Month USD LIBOR + 
 
 
 
150 bps), 5/15/36 (144A) 
11,560,486 
9,709,619(b)  
Motel 6 Trust, Series 2017-MTL6, Class C, 2.105% 
 
 
 
(1 Month USD LIBOR + 140 bps), 8/15/34 (144A) 
8,205,731 
5,220,000(b)  
MTRO Commercial Mortgage Trust, Series 2019-TECH, 
 
 
 
Class C, 2.005% (1 Month USD LIBOR + 
 
 
 
130 bps), 12/15/33 (144A) 
4,800,638 
3,662,523(b)  
Natixis Commercial Mortgage Securities Trust, Series 
 

 
2018-FL1, Class MCR1, 4.009% (1 Month USD
 
 
 
LIBOR + 235 bps), 6/15/35 (144A) 
3,361,899 
11,500,000(b)  
Natixis Commercial Mortgage Securities Trust, Series 
 
 
 
2019-MILE, Class B, 2.505% (1 Month USD LIBOR 
 
 
 
+ 180 bps), 7/15/36 (144A) 
10,811,126 
321,083(b)  
NCUA Guaranteed Notes Trust, Series 2011-C1, Class 2A, 
 
 
 
1.546% (1 Month USD LIBOR + 53 bps), 3/9/21 
320,721 
2,039,294(b)  
RETL, Series 2019-RVP, Class A, 1.855% (1 Month USD 
 
 
 
LIBOR + 115 bps), 3/15/36 (144A) 
1,863,496 
7,006,040(b)  
SLIDE, Series 2018-FUN, Class B, 1.955% (1 Month USD 
 
 
 
LIBOR + 125 bps), 6/15/31 (144A) 
6,371,917 
2,020,108(d)  
Sutherland Commercial Mortgage Loans, Series 
 
 
 
2017-SBC6, Class A, 3.192%, 5/25/37 (144A) 
1,873,695 
4,236,828(d)  
Sutherland Commercial Mortgage Loans, Series 
 
 
 
2018-SBC7, Class A, 4.72%, 5/25/39 (144A) 
3,556,802 
4,374,433(b)  
Tharaldson Hotel Portfolio Trust, Series 2018-THL, 
 
 
 
Class C, 2.355% (1 Month USD LIBOR + 
 
 
 
135 bps), 11/11/34 (144A) 
3,930,757 
7,400,000(b)  
VMC Finance LLC, Series 2018-FL2, Class B, 2.15% 
 
 
 
(1 Month USD LIBOR + 135 bps), 10/15/35 (144A) 
6,530,003 
3,166,400(d)  
WaMu Commercial Mortgage Securities Trust, 
 
 
 
Series 2006-SL1, Class C, 3.717%, 11/23/43 (144A) 
3,192,175 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 63

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Commercial Mortgage-Backed Securities — (continued) 
 
12,800,000(b)  
Wells Fargo Commercial Mortgage Trust, Series 
 
 
 
2017-SMP, Class C, 1.905% (1 Month USD LIBOR + 
 
 
 
120 bps), 12/15/34 (144A) 
$ 10,527,260 
17,500,000(b)  
XCAL Mortgage Trust, Series 2019-1, Class A, 4.4% 
 
 
 
(1 Month USD LIBOR + 225 bps), 11/6/21 (144A) 
17,408,496 
14,200,000(b)  
XCALI Mortgage Trust, Series 2020-1, Class A, 4.05% 
 
 
 
(1 Month USD LIBOR + 240 bps), 1/22/23 (144A) 
14,264,467 
13,500,000(b)  
XCALI Mortgage Trust, Series 2020-2, Class A, 4.05% 
 
 
 
(1 Month USD LIBOR + 200 bps), 2/7/23 (144A) 
13,552,578 
 
 TOTAL COMMERCIAL MORTGAGE-BACKED SECURITIES 
 
 
 
(Cost $676,529,073) 
$ 602,845,300 
 
 CORPORATE BONDS — 14.0% of Net Assets 
 
 
 Auto Manufacturers — 1.1% 
 
2,850,000(b)  
American Honda Finance Corp., 1.807% (3 Month 
 
 
 
USD LIBOR + 54 bps), 6/27/22 
$ 2,648,961 
4,275,000(b)  
American Honda Finance Corp., 1.923% (3 Month 
 
 
 
USD LIBOR + 21 bps), 2/12/21 
4,168,785 
7,500,000(b)  
BMW US Capital LLC, 2.074% (3 Month USD LIBOR + 
 
 
 
37 bps), 8/14/20 (144A) 
7,432,076 
2,015,000(b)  
Ford Motor Credit Co. LLC, 2.728% (3 Month USD LIBOR + 
 
 
 
88 bps), 10/12/21 
1,852,785 
6,750,000(b)  
Nissan Motor Acceptance Corp., 1.261% (3 Month 
 
 
 
USD LIBOR + 52 bps), 3/15/21 (144A) 
6,625,247 
6,020,000  
Nissan Motor Acceptance Corp., 2.55%, 3/8/21 (144A) 
5,795,291 
8,889,000(b)  
PACCAR Financial Corp., 1.994% (3 Month USD LIBOR + 
 
 
 
26 bps), 5/10/21 
8,526,765 
14,245,000(b)  
Volkswagen Group of America Finance LLC, 2.064% 
 
 
 
(3 Month USD LIBOR + 86 bps), 9/24/21 (144A) 
13,046,260 
5,550,000(b)  
Volkswagen Group of America Finance LLC, 2.653% 
 
 
 
(3 Month USD LIBOR + 94 bps), 11/12/21 (144A) 
5,431,225 
 
 Total Auto Manufacturers $ 55,527,395 
 
 Banks — 6.7% 
 
15,262,000(d)  
Bank of America Corp., 2.369%, 7/21/21 
$ 15,251,692 
2,082,000(b)  
Bank of America Corp., 3.239% (3 Month USD LIBOR + 
 
 
 
142 bps), 4/19/21 
2,061,596 
2,675,000(b)  
Bank of Nova Scotia, 2.259% (3 Month USD LIBOR + 
 
 
 
44 bps), 4/20/21 
2,621,386 
6,210,000(b)  
Banque Federative du Credit Mutuel SA, 2.549% 
 
 
 
(3 Month USD LIBOR + 73 bps), 7/20/22 (144A) 
6,127,437 
17,185,000(b)  
Barclays Plc, 3.122% (3 Month USD LIBOR + 
 
 
 
143 bps), 2/15/23 
16,178,371 
1,200,000(b)  
Barclays Plc, 3.459% (3 Month USD LIBOR + 
 
 
 
163 bps), 1/10/23 
1,153,812 
16,311,000(b)  
BPCE SA, 2.903% (3 Month USD LIBOR + 122 bps), 
 
 
 
5/22/22 (144A) 
15,669,325 
 
The accompanying notes are an integral part of these financial statements.
64 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
  Banks — (continued) 
 
4,550,000(b)  
Capital One NA, 2.554%, 8/8/22 
$ 4,452,361 
5,890,000  
Capital One NA, 2.95%, 7/23/21 
5,907,290 
9,095,000(b)  
Citibank NA, 2.063%, 2/12/21 
9,011,353 
6,831,000(b)  
Citigroup, Inc., 2.069% (3 Month USD LIBOR + 
 
  
107 bps), 12/8/21 
6,718,542 
10,771,000  
Citigroup, Inc., 2.7%, 3/30/21 
10,815,781 
12,500,000(b)  
Citigroup, Inc., 2.754% (3 Month USD LIBOR + 
 
  
96 bps), 4/25/22 
12,238,688 
970,000(b)  
Citigroup, Inc., 2.953% (3 Month USD LIBOR + 
 
  
119 bps), 8/2/21 
963,611 
2,320,000(b)  
Credit Suisse Group AG, 1.941% (3 Month USD LIBOR + 
 
  
120 bps), 12/14/23 (144A) 
2,030,292 
1,000,000(b)  
Credit Suisse Group Funding Guernsey, Ltd., 
 
  
4.109%, 4/16/21 
1,000,597 
4,400,000(b)  
DNB Bank ASA, 2.2% (3 Month USD LIBOR + 62 bps), 
 
  
12/2/22 (144A) 
4,191,371 
8,505,000(b)  
Federation des Caisses Desjardins du Quebec, 2.1% 
 
  
(3 Month USD LIBOR + 33 bps), 10/30/20 (144A) 
8,397,342 
2,995,000(b)  
Goldman Sachs Group, Inc., 1.941% (3 Month USD 
 
  
LIBOR + 120 bps), 9/15/20 
2,992,837 
1,000,000(b)  
Goldman Sachs Group, Inc., 2.862%, 11/15/21 
980,000 
13,530,000(b)  
JPMorgan Chase & Co., 2.099%, 6/7/21 
13,477,639 
2,215,000  
JPMorgan Chase & Co., 2.55%, 3/1/21 
2,220,297 
2,905,000(b)  
KeyBank NA, 2.423% (3 Month USD LIBOR + 
 
  
66 bps), 2/1/22 
2,731,014 
8,000,000(b)  
Macquarie Bank, Ltd., 2.187% (3 Month USD LIBOR + 
 
  
45 bps), 8/6/21 (144A) 
7,758,472 
2,968,000(b)  
Mitsubishi UFJ Financial Group, Inc., 2.444% 
 
  
(3 Month USD LIBOR + 65 bps), 7/26/21 
2,844,492 
3,735,000(b)  
Mitsubishi UFJ Financial Group, Inc., 2.584% 
 
  
(3 Month USD LIBOR + 79 bps), 7/25/22 
3,574,221 
6,500,000(b)  
Mizuho Financial Group, Inc., 1.623% (3 Month 
 
  
USD LIBOR + 85 bps), 9/13/23 
5,955,939 
250,000(b)  
Mizuho Financial Group, Inc., 1.648% (3 Month 
 
  
USD LIBOR + 88 bps), 9/11/22 
240,203 
12,195,000(b)  
Mizuho Financial Group, Inc., 2.553% (3 Month 
 
  
USD LIBOR + 94 bps), 2/28/22 
11,739,125 
2,425,000  
PNC Bank NA, 2.0%, 5/19/20 
2,421,776 
4,114,000(b)  
PNC Bank NA, 2.252% (3 Month USD LIBOR + 
 
  
45 bps), 7/22/22 
3,988,112 
2,914,000(b)  
PNC Bank NA, 2.294% (3 Month USD LIBOR + 
 
  
50 bps), 7/27/22 
2,816,192 
7,825,000  
PNC Bank NA, 2.3%, 6/1/20 
7,825,391 
3,175,000  
PNC Bank NA, 2.45%, 11/5/20 
3,180,628 
3,878,000  
PNC Bank NA, 2.5%, 1/22/21 
3,885,696 
5,502,000  
Royal Bank of Canada, 2.15%, 10/26/20 
5,499,227 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 65

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
  Banks — (continued) 
 
445,000(b)  
Royal Bank of Canada, 2.16% (3 Month USD LIBOR + 
 
  
39 bps), 4/30/21 
$ 435,016 
9,000,000(b)  
Royal Bank of Canada, 2.194% (3 Month USD LIBOR + 
 
  
40 bps), 1/25/21 
8,851,828 
2,310,000(b)  
Royal Bank of Canada, 2.245% (3 Month USD LIBOR + 
 
  
47 bps), 4/29/22 
2,217,296 
681,000  
Royal Bank of Canada, 2.35%, 10/30/20 
682,311 
14,715,000(b)  
Skandinaviska Enskilda Banken AB, 1.429% (3 Month 
 
  
USD LIBOR + 65 bps), 12/12/22 (144A) 
13,641,151 
4,232,000(b)  
Sumitomo Mitsui Financial Group, Inc., 2.559% 
 
  
(3 Month USD LIBOR + 74 bps), 10/18/22 
4,192,565 
15,919,000(b)  
Sumitomo Mitsui Financial Group, Inc., 2.618% 
 
  
(3 Month USD LIBOR + 78 bps), 7/12/22 
15,150,563 
3,600,000  
Toronto-Dominion Bank, 1.85%, 9/11/20 
3,595,371 
1,165,000(b)  
Toronto-Dominion Bank, 2.11% (3 Month USD LIBOR + 
 
  
53 bps), 12/1/22 
1,102,381 
1,000,000(b)  
Toronto-Dominion Bank, 2.459% (3 Month USD LIBOR + 
 
  
64 bps), 7/19/23 
924,227 
8,195,000  
Toronto-Dominion Bank, 2.5%, 12/14/20 
8,228,767 
1,035,000(b)  
Toronto-Dominion Bank, 2.874%, 4/7/21 
1,028,720 
8,847,000(b)  
Truist Bank, 2.282% (3 Month USD LIBOR + 
 
  
59 bps), 5/17/22 
8,627,278 
3,970,000(b)  
Truist Financial Corp., 1.983% (3 Month USD LIBOR + 
 
  
22 bps), 2/1/21 
3,841,429 
9,095,000(b)  
US Bank NA, 0.0% (3 Month USD LIBOR + 
 
  
31 bps), 2/4/21 
9,007,732 
1,204,000(b)  
US Bank NA, 1.986%, 5/21/21 
1,183,699 
1,315,000(b)  
US Bank NA, 2.114% (3 Month USD LIBOR + 
 
  
32 bps), 4/26/21 
1,295,018 
12,490,000(b)  
US Bank NA, 2.123% (3 Month USD LIBOR + 
 
  
44 bps), 5/23/22 
12,091,210 
9,451,000  
Wells Fargo & Co., 2.5%, 3/4/21 
9,452,643 
3,350,000(b)  
Wells Fargo & Co., 2.594% (3 Month USD LIBOR + 
 
  
134 bps), 3/4/21 
3,291,682 
9,754,000(b)  
Wells Fargo & Co., 2.661% (3 Month USD LIBOR + 
 
  
93 bps), 2/11/22 
9,566,304 
7,325,000(b)  
Wells Fargo & Co., 2.819% (3 Month USD LIBOR + 
 
  
103 bps), 7/26/21 
7,261,181 
3,776,000  
Wells Fargo & Co., 3.0%, 1/22/21 
3,810,823 
4,849,000  
Wells Fargo & Co., 4.6%, 4/1/21 
4,954,268 
6,430,000(b)  
Wells Fargo Bank NA, 2.258% (3 Month USD LIBOR + 
 
  
62 bps), 5/27/22 
6,338,396 
  Total Banks $ 349,693,967 
 
The accompanying notes are an integral part of these financial statements.
66 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
  Beverages — 0.2% 
 
2,753,000  
Constellation Brands, Inc., 3.75%, 5/1/21 
$ 2,756,407 
3,814,000  
Pernod Ricard SA, 5.75%, 4/7/21 (144A) 
3,924,397 
  Total Beverages $ 6,680,804 
  Chemicals — 0.6% 
 
13,788,000(b)  
Albemarle Corp., 2.742% (3 Month USD LIBOR + 
 
  
105 bps), 11/15/22 (144A) 
$ 13,129,451 
15,830,000(b)  
DuPont de Nemours, Inc., 2.402% (3 Month USD 
 
  
LIBOR + 71 bps), 11/15/20 
15,716,895 
  Total Chemicals $ 28,846,346 
  Commercial Services — 0.0%† 
 
1,510,000  
ERAC USA Finance LLC, 5.25%, 10/1/20 (144A) 
$ 1,534,105 
  Total Commercial Services $ 1,534,105 
  Diversified Financial Services — 0.5% 
 
7,510,000(b)  
AIG Global Funding, 1.931% (3 Month USD LIBOR + 
 
  
48 bps), 7/2/20 (144A) 
$ 7,457,272 
1,855,000(b)  
American Express Co., 2.373% (3 Month USD LIBOR + 
 
  
61 bps), 8/1/22 
1,796,263 
4,005,000(b)  
Capital One Financial Corp., 2.22% (3 Month USD 
 
  
LIBOR + 45 bps), 10/30/20 
3,943,758 
15,850,000(b)  
Capital One Financial Corp., 2.49% (3 Month USD 
 
  
LIBOR + 72 bps), 1/30/23 
14,813,742 
  Total Diversified Financial Services $ 28,011,035 
  Electric — 0.0%† 
 
2,460,000(b)  
Duke Energy Corp., 2.204% (3 Month USD LIBOR + 
 
  
50 bps), 5/14/21 (144A) 
$ 2,434,241 
  Total Electric $ 2,434,241 
  Food — 0.0%† 
 
1,465,000(b)  
Conagra Brands, Inc., 2.552% (3 Month USD LIBOR + 
 
  
75 bps), 10/22/20 
$ 1,449,496 
900,000(b)  
Tyson Foods, Inc., 2.13% (3 Month USD LIBOR + 
 
  
55 bps), 6/2/20 
897,737 
  Total Food $ 2,347,233 
  Gas — 0.1% 
 
6,225,000(b)  
Dominion Energy Gas Holdings LLC, 1.341% (3 Month 
 
  
USD LIBOR + 60 bps), 6/15/21 
$ 5,983,719 
  Total Gas $ 5,983,719 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 67

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
  Healthcare – Services — 0.4% 
 
5,945,000(b)  UnitedHealth Group, Inc., 1.901% (3 Month USD LIBOR + 
 
  7 bps), 10/15/20 $ 5,856,250 
13,650,000  UnitedHealth Group, Inc., 1.95%, 10/15/20 13,647,625 
  Total Healthcare – Services $ 19,503,875 
  Insurance — 0.5% 
 
3,129,000(b)  Allstate Corp., 2.005%, 3/29/23 $ 2,959,215 
 Ambac Assurance Corp., 5.1%, 6/7/20 (144A) 
2(b)  Ambac LSNI LLC, 6.45% (3 Month USD LIBOR + 
 
  500 bps), 2/12/23 (144A) 
2,152,000  Aon Corp., 5.0%, 9/30/20 2,173,653 
4,380,000(b)  Metropolitan Life Global Funding I, 1.695% (SOFRRATE + 
 
  57 bps), 1/13/23 (144A) 3,828,360 
6,190,000  
Metropolitan Life Global Funding I, 2.4%, 1/8/21 (144A) 
6,168,239 
4,531,000(b)  New York Life Global Funding, 2.057% (3 Month 
 
  USD LIBOR + 32 bps), 8/6/21 (144A) 4,403,312 
4,185,000  Protective Life Global Funding, 2.161%, 9/25/20 (144A) 4,157,576 
  Total Insurance $ 23,690,358 

 Machinery – Construction & Mining — 0.1% 
2,600,000(b)  Caterpillar Financial Services Corp., 1.279% (3 Month 
 
  USD LIBOR + 28 bps), 9/7/21 $ 2,503,863 
  Total Machinery – Construction & Mining $ 2,503,863 
  Machinery – Diversified — 0.3% 
 
5,997,000(b)  John Deere Capital Corp., 1.156% (3 Month USD 
 
  LIBOR + 26 bps), 9/10/21 $ 5,802,226 
5,512,000(b)  John Deere Capital Corp., 1.379% (3 Month USD 
 
  LIBOR + 38 bps), 3/7/22 5,329,123 
4,500,000(b)  John Deere Capital Corp., 1.399% (3 Month USD 
 
  LIBOR + 40 bps), 6/7/21 4,416,465 
  Total Machinery – Diversified $ 15,547,814 
  Media — 0.1% 
 
6,499,000(b)  NBCUniversal Enterprise, Inc., 1.833% (3 Month 
 
  USD LIBOR + 40 bps), 4/1/21 (144A) $ 6,412,433 
  Total Media $ 6,412,433 
  Oil & Gas — 0.7% 
 
5,766,000(b)  BP Capital Markets Plc, 1.611% (3 Month USD LIBOR + 
 
  87 bps), 9/16/21 $ 5,673,695 
2,775,000(b)  BP Capital Markets Plc, 1.702% (3 Month USD LIBOR + 
 
  65 bps), 9/19/22 2,770,062 
7,045,000  Canadian Natural Resources, Ltd., 3.45%, 11/15/21 6,576,520 
2,295,000(b)  Chevron Corp., 1.993% (3 Month USD LIBOR + 
 
  53 bps), 3/3/22 2,236,053 
 
The accompanying notes are an integral part of these financial statements.
68 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Oil & Gas — (continued) 
 
10,913,000(b)  
Exxon Mobil Corp., 2.022% (3 Month USD LIBOR + 
 
 
 
33 bps), 8/16/22 
$ 10,010,913 
8,710,000(b)  
Phillips 66, 2.247% (3 Month USD LIBOR + 60  
 
 
 
bps), 2/26/21 
8,147,613 
 
 Total Oil & Gas $ 35,414,856 
 
 Pharmaceuticals — 0.8% 
 
7,636,000(b)  
AbbVie, Inc., 2.346% (3 Month USD LIBOR + 
 
 
 
65 bps), 11/21/22 (144A) 
$ 7,143,715 
4,670,000(b)  
Bayer US Finance II LLC, 1.846% (3 Month USD 
 
 
 
LIBOR + 63 bps), 6/25/21 (144A) 
4,634,844 
12,890,000(b)  
Becton Dickinson & Co., 2.031% (3 Month USD 
 
 
 
LIBOR + 103 bps), 6/6/22 
12,055,876 
2,990,000(b)  
Becton Dickinson & Co., 2.25% (3 Month USD LIBOR + 
 
 
 
88 bps), 12/29/20 
2,889,088 
6,730,000(b)  
Cigna Corp., 1.493% (3 Month USD LIBOR + 65  
 
 
 
bps), 9/17/21 
6,460,800 
11,060,000(b)  
Zoetis, Inc., 2.135% (3 Month USD LIBOR + 
 
 
 
44 bps), 8/20/21 
10,148,691 
 
 Total Pharmaceuticals $ 43,333,014 
 
 Pipelines — 1.2% 
 
9,000,000  
Enterprise Products Operating LLC, 2.8%, 2/15/21 
$ 8,987,542 
3,750,000  
Enterprise Products Operating LLC, 2.85%, 4/15/21 
3,705,860 
3,453,000  
Kinder Morgan, Inc., 5.0%, 2/15/21 (144A) 
3,434,445 
15,605,000(b)  
MPLX LP, 2.099% (3 Month USD LIBOR + 110  
 
 
 
bps), 9/9/22 
14,518,553 
13,330,000  
Sabine Pass Liquefaction LLC, 5.625%, 2/1/21 
12,930,601 
15,900,000(b)  
Spectra Energy Partners LP, 2.014% (3 Month USD 
 
 
 
LIBOR + 70 bps), 6/5/20 
15,730,308 
1,380,000  
Sunoco Logistics Partners Operations LP, 4.4%, 4/1/21 
1,375,601 
 
 Total Pipelines $ 60,682,910 
 
 REITS — 0.2% 
 
7,910,000  
Essex Portfolio LP, 5.2%, 3/15/21 
$ 8,039,324 
 
 Total REITS $ 8,039,324 
 
 Semiconductors — 0.4% 
 
23,276,000  
Broadcom Corp./Broadcom Cayman Finance, Ltd., 
 
 
 
2.2%, 1/15/21 
$ 22,967,763 
 
 Total Semiconductors $ 22,967,763 
 
 Trucking & Leasing — 0.1% 
 
1,400,000(b)  
Aviation Capital Group LLC, 2.44% (3 Month USD 
 
 
 
LIBOR + 67 bps), 7/30/21 (144A) 
$ 1,323,779 
5,010,000(b)  
GATX Corp., 2.461% (3 Month USD LIBOR + 
 
 
 
72 bps), 11/5/21 
4,911,069 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 69

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Trucking & Leasing — (continued) 
 
1,320,000  
Penske Truck Leasing Co. LP/PTL Finance Corp., 3.65%, 
 
 
 
7/29/21 (144A) 
$ 1,336,388 
 
 Total Trucking & Leasing $ 7,571,236 
 
 TOTAL CORPORATE BONDS 
 
 
 
(Cost $750,425,808) 
$ 726,726,291 

 FOREIGN GOVERNMENT BOND — 0.5% of 
 
 Net Assets 
 
 
 United States — 0.5% 
 
25,000,000(b)  
Federal National Mortgage Association, 0.23% 
 
 
 
(SOFRRATE + 22 bps), 3/16/22 
$ 24,950,475 
 
 Total United States $ 24,950,475 
 
 TOTAL FOREIGN GOVERNMENT BOND 
 
 
 
(Cost $24,970,291) 
$ 24,950,475 
 
 INSURANCE-LINKED SECURITIES — 2.2% of 
 
 
 Net Assets(e) 
 
 
 Event Linked Bonds — 1.0% 
 
 
 Earthquakes – California — 0.1% 
 
600,000(b)  
Ursa Re, 4.173% (3 Month U.S. Treasury Bill + 
 
 
 
414 bps), 12/10/20 (144A) 
$ 587,400 
750,000(b)  
Ursa Re, 5.273% (3 Month U.S. Treasury Bill + 
 
 
 
524 bps), 9/24/21 (144A) 
730,500 
500,000(b)  
Ursa Re, 5.783% (3 Month U.S. Treasury Bill + 
 
 
 
575 bps), 12/10/22 (144A) 
485,000 
 
 
 
$ 1,802,900 
 
 Earthquakes – Chile — 0.0%† 
 
1,800,000(b)  
International Bank for Reconstruction & Development, 
 
 
 
3.992% (3 Month USD LIBOR + 250 bps), 
 
 
 
2/15/21 (144A) 
$ 1,755,720 
 
 Earthquakes – Colombia — 0.0%† 
 
1,300,000(b)  
International Bank for Reconstruction & Development, 
 
 
 
4.492% (3 Month USD LIBOR + 300 bps), 
 
 
 
2/15/21 (144A) 
$ 1,259,050 
 
 Earthquakes – Japan — 0.0%† 
 
500,000(b)  
Kizuna Re II, 1.908% (3 Month U.S. Treasury Bill + 
 
 
 
188 bps), 4/11/23 (144A) 
$ 494,450 
450,000(b)  
Nakama Re, 2.912% (6 Month USD LIBOR + 220  
 
 
 
bps), 10/13/21 (144A) 
435,600 
 
 
 
$ 930,050 
 
 Earthquakes – Mexico — 0.0%† 
 
500,000(b)  
International Bank for Reconstruction & Development, 
 
 
 
4.421% (3 Month USD LIBOR + 350 bps), 
 
 
 
3/13/24 (144A) 
$ 499,950 
 
The accompanying notes are an integral part of these financial statements.
70 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Earthquakes – Peru — 0.0%† 
 
700,000(b)  
International Bank for Reconstruction & Development, 
 
 
 
7.492% (3 Month USD LIBOR + 600 bps), 
 
 
 
2/15/21 (144A) 
$ 676,270 
 
 Health – U.S. — 0.1% 
 
250,000(b)  
Vitality Re VIII, 1.783% (3 Month U.S. Treasury Bill + 
 
 
 
175 bps), 1/8/21 (144A) 
$ 212,500 
1,000,000(b)  
Vitality Re VIII, 2.033% (3 Month U.S. Treasury Bill + 
 
 
 
200 bps), 1/8/21 (144A) 
800,000 
3,500,000(b)  
Vitality Re X, 1.783% (3 Month U.S. Treasury Bill + 
 
 
 
175 bps), 1/10/23 (144A) 
2,975,000 
1,750,000(b)  
Vitality Re X, 2.033% (3 Month U.S. Treasury Bill + 
 
 
 
200 bps), 1/10/23 (144A) 
1,400,000 
 
 
 
$ 5,387,500 
 
 Inland Flood – U.S. — 0.0%† 
 
500,000(b)  
FloodSmart Re, 11.278% (3 Month U.S. Treasury Bill + 
 
 
 
1,125 bps), 3/7/22 (144A) 
$ 474,750 
 
 Multiperil – Japan — 0.0%† 
 
250,000(b)  
Akibare Re, 3.323% (3 Month USD LIBOR + 190  
 
 
 
bps), 4/7/22 (144A) 
$ 241,750 
500,000(b)  
Akibare Re, 3.323% (3 Month USD LIBOR + 190  
 
 
 
bps), 4/7/22 (144A) 
479,500 
 
 
 
$ 721,250 
 
 Multiperil – U.S. — 0.4% 
 
1,500,000(b)  
Bonanza RE, 4.783% (3 Month U.S. Treasury Bill + 
 
 
 
475 bps), 2/20/24 (144A) 
$ 1,450,050 
1,250,000(b)  
Caelus Re V, 0.533% (1 Month U.S. Treasury Bill + 
 
 
 
50 bps), 6/5/20 (144A) 
1,087,500 
1,000,000(b)  
Caelus Re V, 3.163% (3 Month U.S. Treasury Bill + 
 
 
 
313 bps), 6/5/20 (144A) 
951,000 
500,000(b)  
Caelus Re V, 3.963% (3 Month U.S. Treasury Bill + 
 
 
 
393 bps), 6/7/21 (144A) 
477,900 
750,000(b)  
Caelus Re V, 4.673% (3 Month U.S. Treasury Bill + 
 
 
 
464 bps), 6/7/21 (144A) 
698,625 
750,000(b)  
Caelus Re VI, 5.533% (3 Month U.S. Treasury Bill + 
 
 
 
550 bps), 6/7/24 (144A) 
720,075 
500,000(b)  
Fortius Re II, 4.913% (6 Month USD LIBOR + 
 
 
 
342 bps), 7/7/21 (144A) 
495,200 
1,700,000(b)  
Kilimanjaro II Re, 8.722% (6 Month USD LIBOR + 
 
 
 
791 bps), 4/21/22 (144A) 
1,646,280 
1,000,000(b)  
Northshore Re II, 7.563% (3 Month U.S. Treasury Bill + 
 
 
 
753 bps), 7/6/20 (144A) 
996,000 
2,350,000(b)  
Residential Reinsurance 2016, 4.003% (3 Month 
 
 
 
U.S. Treasury Bill + 397 bps), 12/6/20 (144A) 
2,313,105 
2,100,000(b)  
Residential Reinsurance 2017, 3.203% (3 Month 
 
 
 
U.S. Treasury Bill + 317 bps), 6/6/21 (144A) 
2,042,040 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 71

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Multiperil – U.S. — (continued) 
 
2,900,000(b)  
Residential Reinsurance 2017, 5.793% (3 Month 
 
 
 
U.S. Treasury Bill + 576 bps), 12/6/21 (144A) 
$ 2,745,140 
1,250,000(b)  
Residential Reinsurance 2018, 3.283% (3 Month 
 
 
 
U.S. Treasury Bill + 325 bps), 6/6/22 (144A) 
1,196,375 
500,000(b)  
Residential Reinsurance 2019, 4.533% (3 Month 
 
 
 
U.S. Treasury Bill + 450 bps), 6/6/23 (144A) 
489,000 
3,350,000(b)  
Tailwind Re, 7.393% (3 Month U.S. Treasury Bill + 
 
 
 
736 bps), 1/8/22 (144A) 
3,268,930 
 
 
 
$ 20,577,220 
 
 Multiperil – U.S. Regional — 0.0%† 
 
1,250,000(b)  
Long Point Re III, 2.783% (3 Month U.S. Treasury Bill + 
 
 
 
275 bps), 6/1/22 (144A) 
$ 1,211,000 
 
 Multiperil – Worldwide — 0.1% 
 
1,250,000(b)  
Galilei Re, 6.704% (6 Month USD LIBOR + 513  
 
 
 
bps), 1/8/21 (144A) 
$ 1,237,000 
550,000(b)  
Galilei Re, 7.254% (6 Month USD LIBOR + 568  
 
 
 
bps), 1/8/21 (144A) 
543,675 
2,300,000(b)  
Galilei Re, 7.454% (6 Month USD LIBOR + 588  
 
 
 
bps), 1/8/21 (144A) 
2,273,320 
 
 
 
$ 4,053,995 
 
 Pandemic – U.S. — 0.1% 
 
1,250,000(b)  
Vitality Re XI, 1.833% (3 Month U.S. Treasury Bill + 
 
 
 
180 bps), 1/9/24 (144A) 
$ 1,000,000 
3,000,000(b)  
Vitality Re XI, 1.533% (3 Month U.S. Treasury Bill + 
 
 
 
150 bps), 1/9/24 (144A) 
2,550,000 
 
 
 
$ 3,550,000 
 
 Pandemic – Worldwide — 0.0%† 
 
1,250,000(b)  
International Bank for Reconstruction & Development, 
 
 
 
8.373% (6 Month USD LIBOR + 690 bps), 
 
 
 
7/15/20 (144A) 
$ 1,000,000 
1,750,000(b)  
Vita Capital VI, Ltd., 4.614% (6 Month USD LIBOR + 
 
 
 
290 bps), 1/8/21 (144A) 
1,645,000 
 
 
 
$ 2,645,000 
 
 Windstorm – Florida — 0.1% 
 
2,500,000(b)  
Casablanca Re, 4.808% (6 Month USD LIBOR + 
 
 
 
402 bps), 6/4/20 (144A) 
$ 2,500,000 
2,500,000(b)  
Integrity Re, 5.564% (3 Month USD LIBOR + 
 
 
 
401 bps), 6/10/22 (144A) 
2,372,250 
 
 
 
$ 4,872,250 
 
 Windstorm – Japan — 0.0%† 
 
1,500,000(b)  
Aozora Re, 3.593% (6 Month USD LIBOR + 200  
 
 
 
bps), 4/7/21 (144A) 
$ 1,474,050 
 
 Windstorm – Mexico — 0.0%† 
 
500,000  
International Bank for Reconstruction & Development, 
 
 
 
7.421%, 3/13/24 
$ 480,750 
 
The accompanying notes are an integral part of these financial statements.
72 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
  Windstorm – U.S. — 0.0%† 
 
250,000(b)  
Bowline Re, 8.85% (3 Month U.S. Treasury Bill + 
 
  
885 bps), 3/20/23 (144A) 
$ 243,250 
  Windstorm – U.S. Multistate — 0.0%† 
 
3,475,000(b)  
Citrus Re, 0.533% (1 Month U.S. Treasury Bill + 
 
  
50 bps), 4/9/20 (144A) 
$ 173,750 
  Windstorm – U.S. Regional — 0.1% 
 
500,000(f)  
Matterhorn Re 2019-1, 12/7/22 (144A) 
$ 480,650 
2,000,000(b)  
Matterhorn Re 2020-1, 7.5% (3 Month U.S. Treasury 
 
  
Bill + 750 bps), 12/7/21 (144A) 
1,928,000 
1,250,000(b)  
Matterhorn Re 2020-2, 6.278% (3 Month U.S. 
 
  
Treasury Bill + 625 bps), 1/8/24 (144A) 
1,204,750 
  
 
$ 3,613,400 
  Total Event Linked Bonds $ 56,402,105 

Face  
 
 
Amount  
 
 
USD ($)  
 
 
  Collateralized Reinsurance — 0.6% 
 
  Earthquakes – California — 0.1% 
 
2,500,000(a)(g)  
Adare Re 2020, 1/31/21 
$ 2,532,512 
  Multiperil – Massachusetts — 0.1% 
 
3,000,000(a)(g)  
Denning Re 2019, 7/31/20 
$ 3,048,046 
  Multiperil – U.S. — 0.1% 
 
500,000(a)(g)  
Dingle Re 2019, 2/1/21 
$ 510,263 
250,000(a)(g)  
Dingle Re 2020, 1/31/21 
240,252 
1,500,000(a)(g)  
Kingsbarns Re 2017, 5/19/20 
1,500 
4,000,000(a)(g)  
Port Royal Re 2019, 5/31/20 
4,105,534 
2,000,000(a)(g)  
Riviera Re 2019, 5/31/20 
2,044,000 
  
 
$ 6,901,549 
  Multiperil – U.S. & Canada — 0.1% 
 
3,250,000(a)(g)  
Leven Re 2020, 1/31/21 
$ 3,180,633 
  Multiperil – U.S. Regional — 0.1% 
 
1,563,421(a)(g)  
Ailsa Re 2018, 6/15/20 
$ 75,670 
2,750,000(a)(g)  
Ailsa Re 2019, 6/30/20 
2,904,505 
2,500,000(a)(g)  
Ocean View Re 2019, 6/30/20 
2,560,414 
  
 
$ 5,540,589 
  Multiperil – Worldwide — 0.1% 
 
1,000,000(a)(g)  
Cypress Re 2017, 1/10/21 
$ 18,200 
3,688,762(a)(g)  
Kilarney Re 2018, 5/31/20 
1,862,087 
24,000(g)  
Limestone Re 2016-1, 8/31/21 
18,890 
40,000(g)  
Limestone Re 2016-1, 8/31/21 
31,484 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 73

Schedule of Investments | 3/31/20 (continued)
    
Face  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Multiperil – Worldwide — (continued) 
 
2,000,000(a)(g)  
Limestone Re 2019-2, 3/1/24 (144A) 
$ 2,077,000 
1,500,000(a)(g)  
Mid Ocean Re 2019, 7/31/20 
1,508,059 
2,500,000(a)(g)  
Resilience Re, 5/1/20 
250 
2,000,000(a)(g)  
Resilience Re, 4/6/21 
200 
 
 
 
$ 5,516,170 
 
 Windstorm – Florida — 0.0%† 
 
2,000,000(a)(g)  
Formby Re 2018, 2/28/21 
$ 377,042 
800,000(a)(g)  
Portrush Re 2017, 6/15/20 
510,480 
 
 
 
$ 887,522 
 
 Windstorm – North Carolina — 0.0%† 
 
1,998,900(g)  
Lahinch Re 2019, 5/31/20 
$ 29,151 
 
 Windstorm – U.S. Regional — 0.0%† 
 
500,000(a)(g)  
Oakmont Re 2017, 4/15/20 
$ 14,700 
2,500,000(a)(g)  
Oakmont Re 2019, 4/30/21 
1,730,780 
1,500,000(g)  
Resilience Re, 6/8/20 
727,500 
 
 
 
$ 2,472,980 
 
 Total Collateralized Reinsurance $ 30,109,152 
 
 Industry Loss Warranties — 0.0%† 
 
 
 Multiperil – U.S. — 0.0%† 
 
2,250,000(a)(g)  
Scotscraig Re 2020, 1/31/21 
$ 2,105,050 
 
 Total Industry Loss Warranties $ 2,105,050 
 
 Reinsurance Sidecars — 0.6% 
 
 
 Multiperil – U.S. — 0.1% 
 
750,000(a)(g)  
Carnoustie Re 2016, 11/30/20 
$ 20,250 
2,000,000(a)(g)  
Carnoustie Re 2017, 11/30/21 
271,700 
1,500,000(g)  
Carnoustie Re 2018, 12/31/21 
16,800 
1,100,000(a)(g)  
Carnoustie Re 2019, 12/31/22 
1,275,450 
1,500,000(a)(g)  
Castle Stuart Re 2018, 12/1/21 
430,820 
2,000,000(a)(h)  
Harambee Re 2018, 12/31/21 
130,000 
4,000,000(h)  
Harambee Re 2019, 12/31/22 
382,000 
625,004(a)(g)  
Sector Re V, Series 7, Class G, 3/1/22 (144A) 
89,437 
 
 
 
$ 2,616,457 
 
 Multiperil – Worldwide — 0.5% 
 
2,000(a)(g)  
Alturas Re 2019-1, 6/3/20 
$ 72,743 
36,448(a)(g)  
Alturas Re 2019-2, 3/10/22 
317,553 
500,000(a)(g)  
Arlington Re 2015, 2/1/21 
24,300 
2,500,000(a)(g)  
Bantry Re 2016, 3/31/21 
201,500 
2,000,000(a)(g)  
Bantry Re 2017, 3/31/21 
472,200 
2,000,000(a)(g)  
Bantry Re 2018, 12/31/21 
22,800 
 
The accompanying notes are an integral part of these financial statements.
74 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Face  
 
 
Amount  
 
 
USD ($)  
 
Value 
  Multiperil – Worldwide — (continued) 
 
4,000,000(g)  
Bantry Re 2019, 12/31/22 
$ 136,000 
1,250,000(a)(g)  
Berwick Re 2017-1, 2/1/21 
41,375 
5,120,164(a)(g)  
Berwick Re 2018-1, 12/31/21 
623,124 
3,658,035(a)(g)  
Berwick Re 2019-1, 12/31/22 
3,947,803 
1,500,000(h)  
Blue Lotus Re 2018, 12/31/21 
93,300 
75,000(g)  
Eden Re II, 3/22/22 (144A) 
100,434 
113,405(g)  
Eden Re II, 3/22/22 (144A) 
130,763 
4,000(a)(g)  
Eden Re II, 3/22/23 (144A) 
34,170 
35,797(a)(g)  
Eden Re II, 3/22/23 (144A) 
314,230 
1,300,000(g)  
Gleneagles Re 2016, 11/30/20 
40,560 
2,118,314(a)(g)  
Gullane Re 2018, 12/31/21 
1,994,625 
2,000(g)  
Limestone Re 2018, 3/1/22 
4,385 
500,000(g)  
Lion Rock Re 2019, 1/31/21 
46,150 
4,000,000(a)(h)  
Lorenz Re 2018, 7/1/21 
286,800 
2,744,544(a)(h)  
Lorenz Re 2019, 6/30/22 
2,481,891 
3,000,000(a)(g)  
Merion Re 2018-2, 12/31/21 
3,268,200 
977,820(a)(h)  
NCM Re 2019, 12/31/22 
216,489 
2,500,000(g)  
Pangaea Re 2015-1, 2/28/21 
3,270 
2,800,000(g)  
Pangaea Re 2015-2, 5/29/20 
4,175 
2,500,000(g)  
Pangaea Re 2016-1, 11/30/20 
5,549 
1,500,000(g)  
Pangaea Re 2016-2, 11/30/20 
4,464 
2,000,000(a)(g)  
Pangaea Re 2017-1, 11/30/21 
32,200 
1,500,000(a)(g)  
Pangaea Re 2017-3, 5/31/22 
76,486 
2,000,000(a)(g)  
Pangaea Re 2018-1, 12/31/21 
117,600 
4,000,000(a)(g)  
Pangaea Re 2018-3, 7/1/22 
82,974 
2,800,000(a)(g)  
Pangaea Re 2019-1, 2/1/23 
58,345 
2,941,254(a)(g)  
Pangaea Re 2019-3, 7/1/23 
2,958,492 
2,400,000(a)(g)  
Sector Re V, 12/1/23 (144A) 
1,715,301 
379(g)  
Sector Re V, Series 8, Class F, 3/1/23 (144A) 
22,253 
1,331(g)  
Sector Re V, Series 8, Class G, 3/1/23 (144A) 
56,311 
2,000,000(a)(g)  
Sector Re V, Series 9, Class A, 3/1/24 (144A) 
1,733,347 
1,600,000(a)(g)  
Sector Re V, Series 9, Class D, 12/1/24 (144A) 
1,671,632 
874,996(a)(g)  
Sector Re V, Series 9, Class G, 3/1/24 (144A) 
1,022,631 
1,250,000(a)(g)  
St. Andrews Re 2017-1, 2/1/21 
84,750 
1,737,984(a)(g)  
St. Andrews Re 2017-4, 6/1/20 
171,018 
750,000(a)(h)  
Thopas Re 2018, 12/31/21 
15,975 
3,000,000(a)(h)  
Thopas Re 2019, 12/31/22 
570,000 
2,600,000(a)(g)  
Versutus Re 2017, 11/30/21 
20,280 
2,000,000(a)(g)  
Versutus Re 2018, 12/31/21 
— 
1,765,095(g)  
Versutus Re 2019-A, 12/31/21 
151,975 
1,434,906(g)  
Versutus Re 2019-B, 12/31/21 
123,545 
750,000(a)(h)  
Viribus Re 2018, 12/31/21 
41,475 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 75

Schedule of Investments | 3/31/20 (continued)
    
Face  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Multiperil – Worldwide — (continued) 
 
2,500,000(h)  
Viribus Re 2019, 12/31/22 
$ 45,250 
1,724,784(a)(g)  
Woburn Re 2018, 12/31/21 
230,776 
809,418(a)(g)  
Woburn Re 2019, 12/31/22 
473,348 
 
 
 
$ 26,364,817 
 
 Total Reinsurance Sidecars $ 28,981,274 
 
 TOTAL INSURANCE-LINKED SECURITIES 
 
 
 
(Cost $126,144,688) 
$ 117,597,581 

Principal  
 
 
Amount  
 
 
USD ($)  
 
 
 
 MUNICIPAL BOND — 0.0%† of Net Assets(i) 
 
 
 Municipal Student Loan — 0.0%† 
 
116,620(b)  
Louisiana Public Facilities Authority, Student Loan Backed, 
 
 
 
Series A, 2.694% (3 Month USD LIBOR + 
 
 
 
90 bps), 4/26/27 
$ 116,590 
 
 Total Municipal Student Loan $ 116,590 
 
 TOTAL MUNICIPAL BOND 
 
 
 
(Cost $117,090) 
$ 116,590 

 SENIOR SECURED FLOATING RATE LOAN 

 INTERESTS — 2.7% of Net Assets*(b) 
 
 Aerospace & Defense — 0.1% 
 
2,424,514  
American Airlines, Inc., 2018 Replacement Term Loan, 
 
 
 
2.709% (LIBOR + 175 bps), 6/27/25 
$ 2,008,710 
744,375  
MRO Holdings, Inc., Initial Term Loan, 6.45% (LIBOR + 
 
 
 
500 bps), 6/4/26 
595,500 
86,135  
United Airlines, Inc., Refinanced Term Loan, 2.739% 
 
 
 
(LIBOR + 175 bps), 4/1/24 
78,382 
 
 Total Aerospace & Defense $ 2,682,592 
 
 Automobile — 0.0%† 
 
1,433,905  
Cooper-Standard Automotive, Inc., Additional Term B-1 
 
 
 
Loan, 2.989% (LIBOR + 200 bps), 11/2/23 
$ 982,225 
468,015  
CWGS Group LLC (aka Camping World, Inc.), Term 
 
 
 
Loan, 3.766% (LIBOR + 275 bps), 11/8/23 
312,789 
291,667  
Visteon Corp., New Term Loan, 2.787% (LIBOR + 
 
 
 
175 bps), 3/25/24 
255,208 
 
 Total Automobile $ 1,550,222 
 
 Beverage, Food & Tobacco — 0.0%† 
 
995,000  
US Foods, Inc. (aka U.S. Foodservice, Inc.), Incremental 
 
 
 
B-2019 Term Loan, 3.072% (LIBOR + 
 
 
 
200 bps), 9/13/26 
$ 927,009 
 
 Total Beverage, Food & Tobacco $ 927,009 
 
The accompanying notes are an integral part of these financial statements.
76 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Broadcasting & Entertainment — 0.1% 
 
1,087,297  
Gray Television, Inc., Term B-2 Loan, 3.765% (LIBOR + 
 
 
 
225 bps), 2/7/24 
$ 1,030,214 
2,000,001  
Gray Television, Inc., Term C Loan, 4.015% (LIBOR + 
 
 
 
250 bps), 1/2/26 
1,930,001 
 
 Total Broadcasting & Entertainment $ 2,960,215 
 
 Building Materials — 0.1% 
 
1,091,190  
Circor International, Inc., New Term Loan, 4.061% 
 
 
 
(LIBOR + 325 bps), 12/11/24 
$ 889,320 
2,739,962  
Summit Materials LLC, New Term Loan, 2.989% (LIBOR + 
 
 
 
200 bps), 11/21/24 
2,428,292 
 
 Total Building Materials $ 3,317,612 
 
 Buildings & Real Estate — 0.2% 
 
2,429,860  
Beacon Roofing Supply, Inc., Initial Term Loan, 3.239% 
 
 
 
(LIBOR + 225 bps), 1/2/25 
$ 2,211,172 
1,012,188  
Cushman & Wakefield US Borrower LLC, Replacement 
 
 
 
Term Loan, 3.739% (LIBOR + 275 bps), 8/21/25 
910,969 
1,277,250  
Southwire Co. LLC (f.k.a Southwire Co.), Initial Term Loan, 
 
 
 
2.739% (LIBOR + 175 bps), 5/19/25 
1,168,684 
2,100,000  
VICI Properties 1 LLC, Term B Loan, 2.674% (LIBOR + 
 
 
 
175 bps), 12/20/24 
1,940,751 
643,435  
WireCo WorldGroup, Inc. (WireCo WorldGroup Finance LP), 
 

 
First Lien Initial Term Loan, 6.072% (LIBOR +
 
 
 
500 bps), 9/29/23 
517,965 
 
 Total Buildings & Real Estate $ 6,749,541 
 
 Chemicals, Plastics & Rubber — 0.2% 
 
2,411,014  
Axalta Coating Systems Dutch Holding B BV (Axalta 
 
 
 
Coating Systems U.S. Holdings, Inc.), Term B-3 Dollar 
 
 
 
Loan, 3.2% (LIBOR + 175 bps), 6/1/24 
$ 2,278,408 
4,466,250  
Berry Global, Inc. (fka Berry Plastics Corp.), Term Y Loan, 
 
 
 
2.863% (LIBOR + 200 bps), 7/1/26 
4,229,539 
1,897,792  
PQ Corp., Third Amendment Tranche B-1 Term Loan, 
 
 
 
4.027% (LIBOR + 225 bps), 2/7/27 
1,726,991 
965,072  
Reynolds Group Holdings, Inc., Incremental US Term Loan, 
 
 
 
3.739% (LIBOR + 275 bps), 2/5/23 
920,437 
4,471,317  
Tronox Finance LLC, First Lien Initial Dollar Term Loan, 
 
 
 
3.93% (LIBOR + 275 bps), 9/23/24 
4,020,460 
292,530  
Twist Beauty International Holdings SA, Facility B2, 
 
 
 
4.907% (LIBOR + 300 bps), 4/22/24 
237,681 
 
 Total Chemicals, Plastics & Rubber $ 13,413,516 
 
 Computers & Electronics — 0.1% 
 
750,000  
Celestica, Inc., Incremental Term B–2 Loan, 3.459% 
 
 
 
(LIBOR + 250 bps), 6/27/25 
$ 667,500 
1,990,000  
NCR Corp., Initial Term Loan, 3.49% (LIBOR + 
 
 
 
250 bps), 8/28/26 
1,820,850 
 
 Total Computers & Electronics $ 2,488,350 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 77

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Consumer Services — 0.0%† 
 
1,036,174  
Prime Security Services Borrower LLC (aka Protection 1 
 

 
Security Solutions), First Lien 2019 Refinancing
 
 
 
Term B-1 Loan, 4.606% (LIBOR + 
 
 
 
325 bps), 9/23/26 
$ 942,919 
 
 Total Consumer Services $ 942,919 
 
 Diversified & Conglomerate Manufacturing — 0.0%† 
 
904,422  
Delos Finance S.a r.l., New Term Loan, 3.2% (LIBOR + 
 
 
 
175 bps), 10/6/23 
$ 807,762 
 
 Total Diversified & Conglomerate Manufacturing $ 807,762 

 Diversified & Conglomerate Service — 0.1% 
2,000,828  
Avis Budget Car Rental LLC, New Tranche B Term Loan, 
 
 
 
2.74% (LIBOR + 175 bps), 8/6/27 
$ 1,730,716 
102,875  
AVSC Holding Corp. (aka PSAV, Inc.), First Lien Initial Term 
 
 
 
Loan, 4.888% (LIBOR + 325 bps), 3/3/25 
64,297 
1,867,900  
Bright Horizons Family Solutions LLC (fka Bright Horizons 
 

 
Family Solutions, Inc.), Term B Loan, 2.739%
 
 
 
(LIBOR + 175 bps), 11/7/23 
1,811,863 
1,038,015  
Change Healthcare Holdings, Inc. (fka Emdeon, Inc.), 
 
 
 
Closing Date Term Loan, 3.498% (LIBOR + 
 
 
 
250 bps), 3/1/24 
958,434 
490,205  
DG Investment Intermediate Holdings 2, Inc. (aka 
 
 
 
Convergint Technologies Holdings LLC), First Lien Initial 
 
 
 
Term Loan, 3.989% (LIBOR + 300 bps), 2/3/25 
424,027 
466,109  
DTI Holdco, Inc., Replacement B-1 Term Loan, 6.527% 
 
 
 
(LIBOR + 475 bps), 9/29/23 
335,598 
1,950,000  
DynCorp International, Inc., Term Loan, 7.0% (LIBOR + 
 
 
 
600 bps), 8/18/25 
1,759,875 
1,950,000  
Iqvia, Inc. (Quintiles IMS), Incremental Term B-2 Dollar 
 
 
 
Loan, 2.739% (LIBOR + 175 bps), 1/17/25 
1,820,812 
869,156  
Jaguar Holding Co. I LLC (fka Jaguar Holding Co. I) (aka 
 

 
Pharmaceutical Product Development LLC), 2018
 
 
 
Term Loan, 3.5% (LIBOR + 250 bps), 8/18/22 
838,012 
1,475,298  
Outfront Media Capital LLC (Outfront Media Capital Corp.), 
 
 
 
Extended Term Loan, 2.547% (LIBOR + 
 
 
 
175 bps), 11/18/26 
1,276,133 
682,456  
Tempo Acquisition LLC, Initial Term Loan, 3.739% (LIBOR + 
 
 
 
275 bps), 5/1/24 
613,073 
410,803  
West Corp., Initial Term B Loan, 5.45% (LIBOR + 
 
 
 
400 bps), 10/10/24 
316,318 
 
 Total Diversified & Conglomerate Service $ 11,949,158 
 
 Electric & Electrical — 0.0%† 
 
391,870  
Rackspace Hosting, Inc., First Lien Term B Loan, 4.763% 
 
 
 
(LIBOR + 300 bps), 11/3/23 
$ 355,622 
 
 Total Electric & Electrical $ 355,622 
 
The accompanying notes are an integral part of these financial statements.
78 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Electronics — 0.1% 
 
2,364,023  
Scientific Games International, Inc., Initial Term B-5 
 
 
 
Loan, 4.246% (LIBOR + 275 bps), 8/14/24 
$ 1,920,769 
1,418,024  
Western Digital Corp., US Term B-4 Loan, 3.353% 
 
 
 
(LIBOR + 175 bps), 4/29/23 
1,371,939 
 
 Total Electronics $ 3,292,708 
 
 Environmental Services — 0.0%† 
 
2,085,246  
GFL Environmental, Inc., Effective Date Incremental Term 
 
 
 
Loan, 3.991% (LIBOR + 300 bps), 5/30/25 
$ 2,034,418 
 
 Total Environmental Services $ 2,034,418 
 
 Healthcare — 0.0%† 
 
525,287  
Grifols Worldwide Operations, Ltd., Dollar Tranche B Term 
 
 
 
Loan, 2.684% (LIBOR + 200 bps), 11/15/27 
$ 503,400 
358,343  
Horizon Therapeutics USA, Inc., Seventh Amendment 
 
 
 
Refinancing Term Loan, 3.313% (LIBOR + 
 
 
 
225 bps), 5/22/26 
339,530 
 
 Total Healthcare $ 842,930 
 
 Healthcare & Pharmaceuticals — 0.0%† 
 
1,266,363  
Acadia Healthcare Co., Inc., Tranche B-4 Term Loan, 
 
 
 
3.5% (LIBOR + 250 bps), 2/16/23 
$ 1,139,727 
1,069,236  
Alkermes, Inc., 2023 Term Loan, 2.87% (LIBOR + 
 
 
 
225 bps), 3/27/23 
951,620 
975,000  
Alphabet Holding Co., Inc. (aka Nature’s Bounty), 
 

 
First Lien Initial Term Loan, 4.489% (LIBOR +
 
 
 
350 bps), 9/26/24 
790,725 
1,508,370  
NMN Holdings III Corp., First Lien Closing Date Term Loan, 
 
 
 
4.739% (LIBOR + 375 bps), 11/13/25 
1,248,176 
299,466  
Prestige Brands, Inc., Term B-4 Loan, 2.989% (LIBOR + 
 
 
 
200 bps), 1/26/24 
280,999 
1,430,000  
Sotera Health Holdings LLC, First Lien Initial Term Loan, 
 
 
 
5.5% (LIBOR + 450 bps), 12/11/26 
1,275,084 
 
 Total Healthcare & Pharmaceuticals $ 5,686,331 

 Healthcare, Education & Childcare — 0.3% 
1,030,158  
ATI Holdings Acquisition, Inc., First Lien Initial Term 
 
 
 
Loan, 4.572% (LIBOR + 350 bps), 5/10/23 
$ 785,495 
2,337,500  
Bausch Health Cos., Inc. (fka Valeant Pharmaceuticals 
 
 
 
International, Inc.), First Incremental Term 
 
 
 
Loan, 3.362% (LIBOR + 275 bps), 11/27/25 
2,228,416 
2,663,590  
Bausch Health Cos., Inc. (fka Valeant Pharmaceuticals 
 

 
International, Inc.), Initial Term Loan, 3.612%
 
 
 
(LIBOR + 300 bps), 6/2/25 
2,552,606 
4,844,922  
LifePoint Health, Inc. (fka Regionalcare Hospital Partners 
 

 
Holdings, Inc.), First Lien Term B Loan, 4.739%
 
 
 
(LIBOR + 375 bps), 11/16/25 
4,457,329 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 79

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Healthcare, Education & Childcare — (continued) 
 
1,485,000  
Vizient, Inc., Term B-6 Loan, 2.989% (LIBOR + 
 
 
 
200 bps), 5/6/26 
$ 1,410,750 
 
 Total Healthcare, Education & Childcare $ 11,434,596 
 
 Hotel, Gaming & Leisure — 0.1% 
 
1,209,192  
1011778 B.C. Unlimited Liability Co. (New Red 
 
 
 
Finance, Inc.) (aka Burger King/Tim Hortons), Term B-4 
 
 
 
Loan, 2.739% (LIBOR + 175 bps), 11/19/26 
$ 1,121,525 
2,008,901  
Boyd Gaming Corp., Refinancing Term B Loan, 2.934% 
 
 
 
(LIBOR + 225 bps), 9/15/23 
1,771,182 
1,000,000  
Hanjin International Corp. (aka Wilshire Grand Center), 
 
 
 
Initial Term Loan, 3.489% (LIBOR + 
 
 
 
250 bps), 10/19/20 
800,000 
 
 Total Hotel, Gaming & Leisure $ 3,692,707 
 
 Insurance — 0.1% 
 
992,500  
Alliant Holdings Intermediate LLC, 2019 New Term Loan, 
 
 
 
3.862% (LIBOR + 325 bps), 5/9/25 
$ 920,544 
69,262  
Alliant Holdings Intermediate LLC, Initial Term Loan, 
 
 
 
3.989% (LIBOR + 300 bps), 5/9/25 
64,356 
4,267,798  
Asurion LLC (fka Asurion Corp.), New B-7 Term Loan, 
 
 
 
3.989% (LIBOR + 300 bps), 11/3/24 
4,018,845 
552,946  
Confie Seguros Holding II Co., Term B Loan, 6.363% 
 
 
 
(LIBOR + 475 bps), 4/19/22 
429,086 
495,168  
Integro Parent, Inc., First Lien Initial Term Loan, 6.75% 
 
 
 
(LIBOR + 575 bps), 10/31/22 
487,740 
341,250  
USI, Inc. (fka Compass Investors, Inc.), 2017 New Term 
 
 
 
Loan, 3.989% (LIBOR + 300 bps), 5/16/24 
311,391 
 
 Total Insurance $ 6,231,962 
 
 Leasing — 0.2% 
 
1,144,959  
Avolon TLB Borrower 1 (US) LLC, Term B-3 Loan, 
 
 
 
2.523% (LIBOR + 175 bps), 1/15/25 
$ 1,032,375 
1,385,491  
Avolon TLB Borrower 1 (US) LLC, Term B-4 Loan, 
 
 
 
2.273% (LIBOR + 150 bps), 2/12/27 
1,246,942 
2,536,757  
Fly Funding II S.a.r.l., Replacement Loan, 3.48% (LIBOR + 
 
 
 
175 bps), 8/11/25 
2,219,662 
2,906,977  
Hertz Corp., Tranche Term B-1 Loan, 3.74% (LIBOR + 
 
 
 
275 bps), 6/30/23 
2,083,334 
980,000  
IBC Capital I, Ltd. (aka Goodpack, Ltd.), First Lien 
 
 
 
Tranche B-1 Term Loan, 4.639% (LIBOR + 
 
 
 
375 bps), 9/11/23 
830,550 
 
 Total Leasing $ 7,412,863 
 
 Leisure & Entertainment — 0.1% 
 
982,500  
24 Hour Fitness Worldwide, Inc., Term Loan, 4.95% 
 
 
 
(LIBOR + 350 bps), 5/30/25 
$ 243,987 
 
The accompanying notes are an integral part of these financial statements.
80 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Leisure & Entertainment — (continued) 
 
2,351,137  
AMC Entertainment Holdings, Inc. (fka AMC 
 
 
 
Entertainment, Inc.), Term B-1 Loan, 4.08% (LIBOR + 
 
 
 
300 bps), 4/22/26 
$ 1,771,189 
729,375  
CityCenter Holdings LLC, Term B Loan, 3.239% (LIBOR + 
 
 
 
225 bps), 4/18/24 
646,408 
1,220,288  
Fitness International LLC, Term B Loan, 4.322% (LIBOR + 
 
 
 
325 bps), 4/18/25 
925,385 
951,871  
Six Flags Theme Parks, Inc., Tranche B Term Loan, 2.74% 
 
 
 
(LIBOR + 175 bps), 4/17/26 
844,547 
 
 Total Leisure & Entertainment $ 4,431,516 
 
 Machinery — 0.1% 
 
97,197  
Clark Equipment Co. (aka Doosan Bobcat, Inc.), 
 

 
Repriced 2019 Term Loan, 3.2% (LIBOR + 175
 
 
 
bps), 5/18/24 
$ 88,611 
1,234,571  
CTC AcquiCo GmbH, Facility B2, 4.363% (LIBOR + 
 
 
 
275 bps), 3/7/25 
1,120,374 
140,772  
Gardner Denver, Inc., 2020 GDI Tranche B-2 Dollar 
 
 
 
Term Loan, 2.739% (LIBOR + 175 bps), 3/1/27 
132,326 
246,125  
NN, Inc., Tranche B Term Loan, 6.689% (LIBOR + 
 
 
 
575 bps), 10/19/22 
183,363 
2,108,942  
Shape Technologies Group, Inc., Initial Term Loan, 4.806% 
 
 
 
(LIBOR + 300 bps), 4/21/25 
1,528,983 
1,732,500  
Terex Corp., 2019 US Term Loan Commitments, 3.739% 
 
 
 
(LIBOR + 275 bps), 1/31/24 
1,624,219 
293,513  
Terex Corp., Incremental US Term Loan, 3.45% (LIBOR + 
 
 
 
200 bps), 1/31/24 
270,032 
 
 Total Machinery $ 4,947,908 
 
 Media — 0.1% 
 
1,352,384  
CSC Holdings LLC (fka CSC Holdings, Inc. (Cablevision)), 
 
 
 
October 2018 Incremental Term Loan, 2.862% (LIBOR 
 
 
 
+ 225 bps), 1/15/26 
$ 1,308,431 
2,175,000  
Ziggo Financing Partnership, Term Loan I Facility, 3.205% 
 
 
 
(LIBOR + 250 bps), 4/30/28 
2,030,906 
 
 Total Media $ 3,339,337 
 
 Metals & Mining — 0.1% 
 
949,352  
Atkore International, Inc., First Lien Initial Incremental 
 
 
 
Term Loan, 4.02% (LIBOR + 275 bps), 12/22/23 
$ 822,775 
984,810  
BWay Holding Co., Initial Term Loan, 5.084% (LIBOR + 
 
 
 
325 bps), 4/3/24 
817,392 
221,875  
Oxbow Carbon LLC, First Lien Tranche B Term Loan, 
 
 
 
4.739% (LIBOR + 375 bps), 1/4/23 
194,141 
1,836,148  
Phoenix Guarantor, Inc. (aka Brightspring), First Lien 
 
 
 
Tranche B-1 Term Loan, 4.113% (LIBOR + 
 
 
 
325 bps), 3/5/26 
1,689,256 
 
 Total Metals & Mining $ 3,523,564 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 81

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Oil & Gas — 0.1% 
 
496,250  
BCP Raptor II LLC, Initial Term Loan, 5.739% (LIBOR + 
 
 
 
475 bps), 11/3/25 
$ 270,456 
4,937,500  
Centurion Pipeline Co. LLC (fka Lotus Midstream LLC), 
 
 
 
Initial Term Loan, 4.239% (LIBOR + 
 
 
 
325 bps), 9/29/25 
3,703,125 
692,954  
Delek US Holdings, Inc., Initial Term Loan, 3.239% 
 
 
 
(LIBOR + 225 bps), 3/31/25 
513,941 
194,116  
Encino Acquisition Partners Holdings LLC, Second Lien 
 
 
 
Initial Term Loan, 7.75% (LIBOR + 
 
 
 
675 bps), 10/29/25 
92,205 
246,673  
Gulf Finance LLC, Tranche B Term Loan, 6.791% (LIBOR + 
 
 
 
525 bps), 8/25/23 
127,448 
553,680  
St. Joseph Energy Center LLC, Term B Advance, 4.5% 
 
 
 
(LIBOR + 350 bps), 4/10/25 
498,312 
 
 Total Oil & Gas $ 5,205,487 
 
 Personal, Food & Miscellaneous Services — 0.0%† 
 
1,221,938  
Option Care Health, Inc., Term B Loan, 5.489% (LIBOR + 
 
 
 
450 bps), 8/6/26 
$ 1,038,647 
 
 Total Personal, Food & Miscellaneous Services $ 1,038,647 
 
 Printing & Publishing — 0.0%† 
 
1,207,856  
Red Ventures LLC (New Imagitas, Inc.), First Lien Tranche 
 
 
 
B-2 Term Loan, 3.489% (LIBOR + 
 
 
 
250 bps), 11/8/24 
$ 1,018,625 
 
 Total Printing & Publishing $ 1,018,625 

 Professional & Business Services — 0.1% 
995,000  
Clear Channel Outdoor Holdings, Inc., Term B Loan, 
 
 
 
4.489% (LIBOR + 350 bps), 8/21/26 
$ 901,719 
3,000,000(j)  
Elanco Animal Health, Inc., Term Loan B, 2/4/27 
2,878,125 
761,947(j)  
Gbt US LLC, Cov-Lite Term Loan, 2/26/27 
666,704 
1,240,625  
MYOB US Borrower LLC, First Lien Initial US Term Loan, 
 
 
 
4.989% (LIBOR + 400 bps), 5/6/26 
1,116,563 
 
 Total Professional & Business Services $ 5,563,111 
 
 Retail — 0.1% 
 
2,000,000  
Aramark Intermediate HoldCo Corp., US Term B-4 
 
 
 
Loan, 2.739% (LIBOR + 175 bps), 1/15/27 
$ 1,870,000 
731,250  
Bass Pro Group LLC, Initial Term Loan, 6.072% (LIBOR + 
 
 
 
500 bps), 9/25/24 
621,563 
2,462,500  
HD Supply, Inc., Term B-5 Loan, 2.739% (LIBOR + 
 
 
 
175 bps), 10/17/23 
2,327,063 
2,384,681  
KFC Holding Co. (aka Yum! Brands), 2018 Term B Loan, 
 
 
 
2.362% (LIBOR + 175 bps), 4/3/25 
2,270,216 
 
 Total Retail $ 7,088,842 
 
The accompanying notes are an integral part of these financial statements.
82 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Securities & Trusts — 0.0%† 
 
1,546,534  
RPI 2019 Intermediate Finance Trust, Term Loan B, 
 
 
 
2.739% (LIBOR + 175 bps), 2/11/27 
$ 1,443,431 
382,757  
RPI Intermediate Finance Trust, Term B-1 Term Facility, 
 
 
 
2.739% (LIBOR + 175 bps), 2/11/27 
357,240 
 
 Total Securities & Trusts $ 1,800,671 
 
 Telecommunications — 0.2% 
 
3,042,375  
CenturyLink, Inc., Term B Loan, 3.239% (LIBOR + 
 
 
 
225 bps), 3/15/27 
$ 2,827,507 
2,499,750  
Ciena Corp., Refinancing Term Loan, 2.523% (LIBOR + 
 
 
 
175 bps), 9/26/25 
2,374,763 
2,448,748  
Go Daddy Operating Co. LLC (GD Finance Co., Inc.), 
 
 
 
Tranche B-2 Term Loan, 2.739% (LIBOR + 
 
 
 
175 bps), 2/15/24 
2,356,920 
1,990,234  
Level 3 Financing, Inc., Tranche B 2027 Term Loan, 
 
 
 
2.739% (LIBOR + 175 bps), 3/1/27 
1,880,771 
1,484,673  
Virgin Media Bristol LLC, N Facility, 3.205% (LIBOR + 
 
 
 
250 bps), 1/31/28 
1,414,151 
680,541  
Windstream Services LLC (fka Windstream Corp.), 
 

 
Tranche B-7 Term Loan, 7.5% (PRIME + 425
 
 
 
bps), 2/17/24 
421,935 
 
 Total Telecommunications $ 11,276,047 
 
 Transportation — 0.0%† 
 
2,419,375  
Envision Healthcare Corp., Initial Term Loan, 4.739% 
 
 
 
(LIBOR + 375 bps), 10/10/25 
$ 1,296,785 
62,461  
Syncreon Group BV, Second Out Term Loan, 7.45% 
 
 
 
(LIBOR + 600 bps), 4/1/25 
44,581 
 
 Total Transportation $ 1,341,366 
 
 Utilities — 0.1% 
 
1,209,216  
APLP Holdings, Ltd. Partnership, Term Loan, 3.5% 
 
 
 
(LIBOR + 250 bps), 4/14/25 
$ 1,178,986 
757,563  
Calpine Construction Finance Co., LP, Term B Loan, 
 
 
 
2.989% (LIBOR + 200 bps), 1/15/25 
715,897 
497,500  
Calpine Corp., Term Loan, 2.989% (LIBOR + 
 
 
 
200 bps), 8/12/26 
468,894 
489,940  
Eastern Power LLC (Eastern Covert Midco LLC) (aka 
 
 
 
TPF II LC LLC), Term Loan, 4.75% (LIBOR + 
 
 
 
375 bps), 10/2/25 
429,716 
568,884  
Vistra Operations Co. LLC (fka Tex Operations Co. LLC), 
 

 
2018 Incremental Term Loan, 2.703% (LIBOR +
 
 
 
175 bps), 12/31/25 
545,417 
 
 Total Utilities $ 3,338,910 
 
 TOTAL SENIOR SECURED FLOATING RATE 
 
 
 LOAN INTERESTS 
 
 
 
(Cost $161,561,695) 
$ 142,687,064 
 
The accompanying notes are an integral part of these financial statements.


Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 83

Schedule of Investments | 3/31/20 (continued)
    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 U.S. GOVERNMENT AND AGENCY 
 
 
 OBLIGATIONS — 9.9% of Net Assets 
 
7,199(b)  
Fannie Mae, 3.723% (2 Month USD LIBOR + 
 
 
 
168 bps), 1/1/48 
$ 7,380 
6,299(b)  
Fannie Mae, 3.795% (1 Year CMT Index + 
 
 
 
217 bps), 2/1/34 
6,312 
8,133(b)  
Fannie Mae, 4.106% (1 Year CMT Index + 
 
 
 
211 bps), 9/1/32 
8,349 
250(b)  
Fannie Mae, 4.301% (1 Year CMT Index + 
 
 
 
232 bps), 11/1/23 
253 
7,181(b)  
Fannie Mae, 4.559% (1 Year CMT Index + 
 
 
 
219 bps), 10/1/32 
7,244 
10,042(b)  
Federal Home Loan Mortgage Corp., 4.125% (2 Month 
 
 
 
USD LIBOR + 200 bps), 11/1/33 
10,138 
1,152(b)  
Federal Home Loan Mortgage Corp., 4.371% (3 Year 
 
 
 
CMT Index + 212 bps), 6/1/35 
1,166 
686(b)  
Federal Home Loan Mortgage Corp., 4.499% (1 Year 
 
 
 
CMT Index + 230 bps), 10/1/23 
691 
1,716(b)  
Government National Mortgage Association II, 4.0% 
 
 
 
(1 Year CMT Index + 150 bps), 1/20/22 
1,732 
511,160,000(b)  
U.S. Treasury Floating Rate Notes, 0.385% (3 Month U.S. 
 
 
 
Treasury Bill Money Market Yield + 
 
 
 
30 bps), 10/31/21 
512,634,415 
 
 TOTAL U.S. GOVERNMENT AND AGENCY OBLIGATIONS 
 
 
 
(Cost $512,996,375) 
$ 512,677,680 
 
 TEMPORARY CASH INVESTMENTS — 6.6% of 
 
 
 Net Assets 
 
 
 CERTIFICATES OF DEPOSIT — 0.6% 
 
6,200,000  
Bank of Montreal, 1.8%, 4/3/20 
$ 6,200,823 
6,100,000(b)  
Lloyds Bank Corporate Markets Plc, 2.369% (3 Month 
 
 
 
USD LIBOR + 55 bps), 7/19/21 
6,037,897 
13,700,000  
Norinchukin Bank, 1.94%, 4/9/20 
13,705,379 
6,000,000(b)  
Svenska Handelsbanken AB, 1.567% (1 Month USD 
 
 
 
LIBOR + 19 bps), 5/5/20 
6,002,424 
1,135,000(b)  
Swedbank AB, 2.003% (3 Month USD LIBOR + 32  
 
 
 
bps), 8/24/20 
1,133,734 
 
 
 
$ 33,080,257 
 
 COMMERCIAL PAPERS — 4.1% 
 
9,000,000  
Anthem, Inc., 1.724%, 4/20/20 
$ 8,992,915 
397,000  
Aon Corp., 1.352%, 4/6/20 
396,818 
25,000,000  
BASF SE, 2.001%, 4/8/20 
24,992,467 
7,000,000  
Boeing Co., 1.956%, 4/7/20 
6,995,236 
7,030,000  
Boeing Co., 2.029%, 5/14/20 
6,997,633 
10,000,000  
Boeing Co., 2.03%, 5/20/20 
9,946,986 
25,000,000  
DNB Bank ASA, 0.08%, 4/7/20 
24,999,222 
 
The accompanying notes are an integral part of these financial statements.
84 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Principal  
 
 
Amount  
 
 
USD ($)  
 
Value 
 
 Commercial Papers — (continued) 
 
8,500,000  
Eni Finance USA, Inc., 1.808%, 5/28/20 
$ 8,478,815 
4,200,000  
Eni Finance USA, Inc., 1.882%, 4/2/20 
4,199,892 
25,000,000  
Federation des Caisses Desjardins du Quebec, 
 
 
 
0.07%, 4/1/20 
24,999,990 
25,000,000  
LVMH Moet Hennessy Louis Vuitton SE, 0.5%, 4/7/20 
24,997,520 
25,000,000  
Nordea Bank Abp, 0.01%, 4/1/20 
25,000,043 
4,550,000  
Puget Sound Energy, Inc., 2.001%, 4/8/20 
4,547,112 
25,000,000  
Societe Generale North America, Inc., 0.005%, 4/1/20 
25,000,043 
9,700,000  
TransCanada PipeLines, Ltd., 1.849%, 4/27/20 
9,676,233 
 
 
 
$ 210,220,925 
 
 REPURCHASE AGREEMENTS — 1.9% 
 
20,880,000  
$20,880,000 Merrill Lynch, Pierce, Fenner & Smith, Inc., 
 

 
0.01%, dated 3/31/20 plus accrued interest on
 

 
4/1/20 collateralized by $21,297,600 U.S.
 
 
 
Treasury Notes, 1.8%-2.0%, 5/15/22-1/15/26. 
$ 20,880,000 
28,000,000  
$28,000,000 RBC Capital Markets LLC, 0.01%, 
 

 
dated 3/31/20 plus accrued interest on 4/1/20
 
 
 
collateralized by the following: 
 
 
 
$19,484,325 Federal National Mortgage Association, 
 
 
 
4.0%-4.5%, 10/1/48-2/1/49 
 

 
$7,685,399 Freddie Mac Giant, 3.5%, 7/1/48
 

 
$1,390,285 Government National Mortgage
 
 
 
Association, 4.0%, 3/20/50. 
28,000,000 
26,020,000  
$26,020,000 TD Securities USA LLC, 0.01%, dated 
 
 
 
3/31/20 plus accrued interest on 4/1/20 collateralized 
 
 
 
by the following: 
 
 
 
$13,270,201 Federal National Mortgage Association, 
 
 
 
3.0%, 3/1/50 
 

 
$13,270,262 U.S. Treasury Notes, 0.0%-0.8%,
 
 
 
7/31/20-2/15/50. 
26,020,000 
25,880,000  
$25,880,000 ScotiaBank, 0.01%, dated 3/31/20 plus 
 

 
accrued interest on 4/1/20 collateralized by
 

 
$26,397,648 U.S. Treasury Notes, 2.8%-2.9%,
 
 
 
11/5/23-2/15/28. 
25,880,000 
 
 
 
$ 100,780,000 
 
 TOTAL TEMPORARY CASH INVESTMENTS 
 
 
 
(Cost $344,185,515) 
$ 344,081,182 
 
 TOTAL INVESTMENTS IN UNAFFILIATED 
 
 
 ISSUERS — 96.2% 
 
 
 
(Cost $5,279,526,888) 
$5,008,156,341 
 
 OTHER ASSETS AND LIABILITIES — 3.8% $ 196,232,942 
 
 NET ASSETS — 100.0% $5,204,389,283 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 85

Schedule of Investments | 3/31/20 (continued)
  
bps 
Basis Points. 
CMT 
Constant Maturity Treasury. 
FREMF 
Freddie Mac Multifamily Fixed-Rate Mortgage Loans. 
LIBOR 
London Interbank Offered Rate. 
PRIME 
U.S. Federal Funds Rate. 
REIT 
Real Estate Investment Trust. 
REMICS 
Real Estate Mortgage Investment Conduits. 
SOFRRATE 
Secured Overnight Financing Rate. 
Strips 
Separate trading of Registered interest and principal of securities. 
(144A) 
Security is exempt from registration under Rule 144A of the Securities Act of 1933. Such securities may be resold normally to qualified institutional buyers in a transaction exempt from registration. At March 31, 2020, the value of these securities amounted to$2,920,442,280, or 56.1% of net assets. 
† 
Amount rounds to less than 0.1%. 
Senior secured floating rate loan interests in which the Fund invests generally pay interest at rates that are periodically redetermined by reference to a base lending rate plus a premium. These base lending rates are generally (i) the lending rate offered by one or more major European banks, such as LIBOR, (ii) the prime rate offered by one or more major United States banks, (iii) the rate of a certificate of deposit or (iv) other base lending rates used by commercial lenders. The interest rate shown is the rate accruing at March 31, 2020. 
Security that used significant unobservable inputs to determine its value. 
(a) 
Non-income producing security. 
(b) 
Floating rate note. Coupon rate, reference index and spread shown at March 31, 2020. 
(c) 
Debt obligation initially issued at one coupon which converts to a higher coupon at a 
specific date. The rate shown is the rate at March 31, 2020. 
(d) 
The interest rate is subject to change periodically. The interest rate and/or reference index and spread shown at March 31, 2020. 
(e) 
Securities are restricted as to resale. 
(f) 
Security issued with a zero coupon. Income is recognized through accretion of discount. 
(g) 
Issued as participation notes. 
(h) 
Issued as preference shares. 
(i) 
Consists of Revenue Bonds unless otherwise indicated. 
(j) 
This term loan will settle after March 31, 2020, at which time the interest rate will be determined. 
 
Principal amounts are denominated in U.S. dollars (“USD”) unless otherwise noted.
The accompanying notes are an integral part of these financial statements.
86 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

Purchases and sales of securities (excluding temporary cash investments) for the year ended March 31, 2020 were as follows:
       
 
 Purchases  Sales 
Long-Term U.S. Government Securities 
 
$
990,350,036
  
$
716,965,967
 
Other Long-Term Securities 
 
$
4,595,711,694
  
$
5,462,947,682
 
 
The Fund is permitted to engage in purchase and sale transactions (“cross trades”) with certain funds and accounts for which Amundi Pioneer Asset Management, Inc. (the “Adviser”) serves as the Fund’s investment adviser, as set forth in Rule 17a-7 under the Investment Company Act of 1940, pursuant to procedures adopted by the Board of Trustees. Under these procedures, cross trades are effected at current market prices. During the year ended March 31, 2020, the Fund engaged in purchases of $6,349,102 and sales of $4,490,383 pursuant to these procedures, which resulted in a net realized gain/(loss) of $(3,960).
At March 31, 2020, the net unrealized depreciation on investments based on cost for federal tax purposes of $5,291,958,192 was as follows:
    
Aggregate gross unrealized appreciation for all investments in which    
there is an excess of value over tax cost  
$
6,418,466
 
Aggregate gross unrealized depreciation for all investments in which     
there is an excess of tax cost over value   
(290,220,317
)
Net unrealized depreciation  
$
(283,801,851
)
 
Various inputs are used in determining the value of the Fund’s investments. These inputs are summarized in the three broad levels below.
Level 1 – quoted prices in active markets for identical securities.
Level 2 – other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risks, etc.). See Notes to Financial Statements — Note 1A.
Level 3 – significant unobservable inputs (including the Fund’s own assumptions in determining fair value of investments). See Notes to Financial Statements — Note 1A.
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 87

Schedule of Investments | 3/31/20 (continued)
The following is a summary of the inputs used as of March 31, 2020, in valuing the Fund’s investments:
             
 
 Level 1  Level 2  Level 3  Total 
Common Stock 
            
Transportation Infrastructure  
$
  
$
12,678
  
$
  
$
12,678
 
Asset Backed Securities 
  
   
1,746,889,150
   
   
1,746,889,150
 
Collateralized Mortgage 
                
Obligations   
   
789,572,350
   
   
789,572,350
 
Commercial Mortgage-Backed 
                
Securities   
   
602,845,300
   
   
602,845,300
 
Corporate Bonds 
  
   
726,726,291
   
   
726,726,291
 
Foreign Government Bond 
  
   
24,950,475
   
   
24,950,475
 
Insurance-Linked Securities 
                
Event Linked Bonds                 
Windstorm - Mexico   
   
   
480,750
   
480,750
 
Collateralized Reinsurance                 
Earthquakes - California   
   
   
2,532,512
   
2,532,512
 
Multiperil - Massachusetts   
   
   
3,048,046
   
3,048,046
 
Multiperil - U.S.   
   
   
6,901,549
   
6,901,549
 
Multiperil - U.S. & Canada   
   
   
3,180,633
   
3,180,633
 
Multiperil - U.S. Regional   
   
   
5,540,589
   
5,540,589
 
Multiperil - Worldwide   
   
   
5,516,170
   
5,516,170
 
Windstorm - Florida   
   
   
887,522
   
887,522
 
Windstorm - North Carolina   
   
   
29,151
   
29,151
 
Windstorm - U.S. Regional   
   
   
2,472,980
   
2,472,980
 
Industry Loss Warranties                 
Multiperil - U.S.   
   
   
2,105,050
   
2,105,050
 
Reinsurance Sidecars                 
Multiperil - U.S.   
   
   
2,616,457
   
2,616,457
 
Multiperil - Worldwide   
   
   
26,364,817
   
26,364,817
 
All Other Insurance-Linked                 
Securities   
   
55,921,355
   
   
55,921,355
 
Municipal Bond 
  
   
116,590
   
   
116,590
 
Senior Secured Floating 
                
Rate Loan Interests   
   
142,687,064
   
   
142,687,064
 
U.S. Government and 
                
Agency Obligations   
   
512,677,680
   
   
512,677,680
 
Certificates of Deposit 
  
   
33,080,257
   
   
33,080,257
 
Commercial Papers 
  
   
210,220,925
   
   
210,220,925
 
  
Repurchase Agreements 
  
   
100,780,000
   
   
100,780,000
 
Total Investments in Securities  $  $4,946,480,115  $61,676,226  $5,008,156,341 
 
The accompanying notes are an integral part of these financial statements.
88 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

The following is a reconciliation of assets valued using significant unobservable inputs (Level 3):
    
 
 Insurance- 
 
 Linked 
 
 Securities 
Balance as of 3/31/19 
 
$
90,513,904
 
Realized gain (loss)(1) 
  
(384,569
)
Change in unrealized appreciation(2) 
  
1,015,179
 
Accrued discounts/premiums 
  
 
Purchases 
  
43,039,024
 
Sales 
  
(72,507,312
)
Transfers in to Level 3* 
�� 
 
Transfers out of Level 3* 
  
 
Balance as of 3/31/20  $61,676,226 
 
   
(1)
Realized gain (loss) on these securities is included in the realized gain (loss) from investments on the Statement of Operations. 
(2) 
Unrealized appreciation (depreciation) on these securities is included in the change in unrealized appreciation (depreciation) from investments on the Statement of Operations. 
Transfers are calculated on the beginning of period value. For the year ended March 31, 2020, there were no transfers between Levels 1, 2 and 3.
 
 
Net change in unrealized appreciation (depreciation) of Level 3 investments still held and considered 
 
Level 3 at March 31, 2020: 
$2,002,682 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 89

Statement of Assets and Liabilities | 3/31/20
    
ASSETS:    
Investments in unaffiliated issuers, at value (cost $5,279,526,888)  
$
5,008,156,341
 
Cash   
581,290,354
 
Receivables —     
Investment securities sold   
117,327,165
 
Fund shares sold   
46,361,578
 
Interest   
9,594,235
 
Other assets   
232,943
 
Total assets  $5,762,962,616 
LIABILITIES:     
Payables —     
Investment securities purchased  
$
509,747,591
 
Fund shares repurchased   
46,146,524
 
Distributions   
1,141,032
 
Trustees’ fees   
4,523
 
Unrealized depreciation on unfunded loan commitments   
122,329
 
Due to affiliates   
295,877
 
Accrued expenses   
1,115,457
 
Total liabilities  $558,573,333 
NET ASSETS:     
Paid-in capital  
$
5,691,436,283
 
Distributable earnings (loss)   
(487,047,000
)
Net assets  $5,204,389,283 
NET ASSET VALUE PER SHARE:     
No par value (unlimited number of shares authorized)     
Class A (based on $1,628,082,307/175,843,458 shares)  
$
9.26
 
Class C (based on $300,129,408/32,402,694 shares)  
$
9.26
 
Class C2 (based on $20,982,095/2,264,362 shares)  
$
9.27
 
Class K (based on $264,405,157/28,474,598 shares)  
$
9.29
 
Class Y (based on $2,990,790,316/322,506,747 shares)  
$
9.27
 
 
The accompanying notes are an integral part of these financial statements.
90 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

Statement of Operations
FOR THE YEAR ENDED 3/31/20
       
INVESTMENT INCOME:       
Interest from unaffiliated issuers  
$
189,338,728
    
Dividends from unaffiliated issuers   
3,387,079
    
Total investment income      $192,725,807 
EXPENSES:         
Management fees  
$
18,452,386
     
Administrative expense   
1,507,789
     
Transfer agent fees         
Class A   
416,062
     
Class C   
136,028
     
Class C2   
3,323
     
Class K   
536
     
Class Y   
2,842,027
     
Distribution fees         
Class A   
3,543,223
     
Class C   
1,916,747
     
Class C2   
61,671
     
Shareowner communications expense   
161,251
     
Custodian fees   
257,123
     
Registration fees   
401,180
     
Professional fees   
333,617
     
Printing expense   
80,828
     
Pricing fees   
310,497
     
Trustees’ fees   
329,367
     
Insurance expense   
70,534
     
Miscellaneous   
228,287
     
Total expenses      
$
31,052,476
 
Net investment income      $161,673,331 
REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS:         
Net realized gain (loss) on:         
Investments in unaffiliated issuers      
$
(167,329,917
)
Change in net unrealized appreciation (depreciation) on:         
Investments in unaffiliated issuers  
$
(254,042,856
)
    
Unfunded loan commitments   
(118,596
)
    
Other assets and liabilities denominated in         
foreign currencies   
217
  
$
(254,161,235
)
Net realized and unrealized gain (loss) on investments      $(421,491,152)
Net decrease in net assets resulting from operations      $(259,817,821)
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 91

Statements of Changes in Net Assets
       
 
 Year  Year 
 
 Ended  Ended 
 
 3/31/20  3/31/19 
FROM OPERATIONS:       
Net investment income (loss) 
 
$
161,673,331
  
$
139,593,455
 
Net realized gain (loss) on investments 
  
(167,329,917
)
  
(1,981,291
)
Change in net unrealized appreciation (depreciation) 
        
on investments   
(254,161,235
)
  
(15,456,309
)
Net increase (decrease) in net assets resulting         
from operations  $(259,817,821) $122,155,855 
DISTRIBUTIONS TO SHAREOWNERS:         
Class A ($0.27 and $0.26 per share, respectively)  
$
(48,393,422
)
 
$
(36,341,184
)
Class C ($0.24 and $0.23 per share, respectively)   
(9,350,830
)
  
(11,382,084
)
Class C2 ($0.24 and $0.23 per share, respectively)   
(292,948
)
  
(189,452
)
Class K ($0.30 and $0.28 per share, respectively)   
(10,737,706
)
  
(5,789,037
)
Class Y ($0.29 and $0.27 per share, respectively)   
(105,798,339
)
  
(88,207,485
)
Total distributions to shareowners  
$
(174,573,245
)
 
$
(141,909,242
)
FROM FUND SHARE TRANSACTIONS:         
Net proceeds from sales of shares 
 
$
5,510,392,928
  
$
5,435,371,909
 
Reinvestment of distributions 
  
158,619,800
   
123,987,280
 
Cost of shares repurchased 
  
(5,915,746,371
)
  
(4,163,986,271
)
Net increase (decrease) in net assets resulting from         
Fund share transactions  
$
(246,733,643
)
 
$
1,395,372,918
 
Net increase (decrease) in net assets  $(681,124,709) $1,375,619,531 
NET ASSETS:         
Beginning of year 
 
$
5,885,513,992
  
$
4,509,894,461
 
End of year 
 $5,204,389,283  $5,885,513,992 
 
The accompanying notes are an integral part of these financial statements.
92 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

             
 
 Year Ended  Year Ended  Year Ended  Year Ended 
 
 3/31/20  3/31/20  3/31/19  3/31/19 
 
 Shares  Amount  Shares  Amount 
Class A             
Shares sold 
  
207,659,616
  
$
2,059,762,141
   
150,053,164
  
$
1,492,141,016
 
Reinvestment of distributions 
  
4,724,639
   
46,618,899
   
3,447,856
   
34,237,849
 
Less shares repurchased 
  
(188,391,509
)
  
(1,839,757,207
)
  
(123,191,698
)
  
(1,224,211,031
)
Net increase   
23,992,746
  
$
266,623,833
   
30,309,322
  
$
302,167,834
 
Class C                 
Shares sold 
  
11,059,054
  
$
109,569,322
   
9,449,781
  
$
93,876,062
 
Reinvestment of distributions 
  
945,924
   
9,341,514
   
1,139,347
   
11,304,487
 
Less shares repurchased 
  
(22,585,668
)
  
(221,897,172
)
  
(30,337,629
)
  
(301,269,304
)
Net decrease   
(10,580,690
)
 
$
(102,986,336
)
  
(19,748,501
)
 
$
(196,088,755
)
Class C2                 
Shares sold 
  
1,697,084
  
$
16,812,541
   
304,143
  
$
3,017,620
 
Reinvestment of distributions 
  
7,983
   
78,821
   
10,421
   
103,386
 
Less shares repurchased 
  
(309,176
)
  
(2,999,390
)
  
(344,484
)
  
(3,418,732
)
Net increase/                 
(decrease)   
1,395,891
  
$
13,891,972
   
(29,920
)
 
$
(297,726
)
Class K                 
Shares sold 
  
16,044,359
  
$
159,364,345
   
26,908,751
  
$
267,357,993
 
Reinvestment of distributions 
  
1,078,075
   
10,665,224
   
461,075
   
4,581,504
 
Less shares repurchased 
  
(16,312,518
)
  
(159,929,239
)
  
(15,608,370
)
  
(155,221,276
)
Net increase   
809,916
  
$
10,100,330
   
11,761,456
  
$
116,718,221
 
Class Y                 
Shares sold 
  
319,898,241
  
$
3,164,884,579
   
359,915,914
  
$
3,578,979,218
 
Reinvestment of distributions 
  
9,300,699
   
91,915,342
   
7,424,296
   
73,760,054
 
Less shares repurchased 
  
(376,494,340
)
  
(3,691,163,363
)
  
(249,523,007
)
  
(2,479,865,928
)
Net increase/                 
(decrease)   
(47,295,400
)
 
$
(434,363,442
)
  
117,817,203
  
$
1,172,873,344
 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 93

Financial Highlights
                
 
 Year  Year  Year  Year  Year 
 
 Ended  Ended  Ended  Ended  Ended 
 
 3/31/20  3/31/19  3/31/18  3/31/17*  3/31/16* 
Class A                
Net asset value, beginning of period 
 
$
9.92
  
$
9.95
  
$
9.99
  
$
9.92
  
$
10.00
 
Increase (decrease) from investment operations: 
                    
Net investment income (loss)(a)  
$
0.25
  
$
0.26
  
$
0.18
  
$
0.16
  
$
0.10
 
Net realized and unrealized gain (loss) on investments   
(0.64
)
  
(0.03
)
  
(0.03
)
  
0.08
   
(0.06
)
Net increase (decrease) from investment operations 
 $(0.39) $0.23  $0.15  $0.24  $0.04 
Distributions to shareowners: 
                    
Net investment income  
$
(0.27
)
 
$
(0.26
)
 
$
(0.19
)
 
$
(0.17
)
 
$
(0.12
)
Net increase (decrease) in net asset value 
 $(0.66) $(0.03) $(0.04) $0.07  $(0.08)
Net asset value, end of period 
 
$
9.26
  
$
9.92
  
$
9.95
  
$
9.99
  
$
9.92
 
Total return(b) 
  (4.02)%  2.32%  1.51%  2.43%  0.41%
Ratio of net expenses to average net assets 
  
0.58
%
  
0.59
%
  
0.60
%
  
0.61
%
  
0.63
%
Ratio of net investment income (loss) to average net assets 
  
2.52
%
  
2.58
%
  
1.81
%
  
1.59
%
  
1.01
%
Portfolio turnover rate 
  
100
%
  
61
%
  
54
%
  
69
%
  
58
%
Net assets, end of period (in thousands) 
 
$
1,628,082
  
$
1,506,433
  
$
1,209,820
  
$
759,455
  
$
673,352
 
 
  
The Fund was audited by an independent registered public accounting firm other than Ernst & Young LLP. 
(a) 
The per share data presented above is based on the average shares outstanding for the period presented. 
(b) 
Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period and no sales charges. Total return would be reduced if sales charges were taken into account. 
 
The accompanying notes are an integral part of these financial statements.
94 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

                
 
 Year  Year  Year  Year  Year 
 
 Ended  Ended  Ended  Ended  Ended 
 
 3/31/20  3/31/19  3/31/18  3/31/17*  3/31/16* 
Class C                
Net asset value, beginning of period 
 
$
9.91
  
$
9.94
  
$
9.97
  
$
9.91
  
$
9.99
 
Increase (decrease) from investment operations: 
                    
Net investment income (loss)(a)  
$
0.22
  
$
0.22
  
$
0.15
  
$
0.13
  
$
0.07
 
Net realized and unrealized gain (loss) on investments   
(0.63
)
  
(0.02
)
  
(0.02
)
  
0.07
   
(0.06
)
Net increase (decrease) from investment operations 
 $(0.41) $0.20  $0.13  $0.20  $0.01 
Distributions to shareowners: 
                    
Net investment income  
$
(0.24
)
 
$
(0.23
)
 
$
(0.16
)
 
$
(0.14
)
 
$
(0.09
)
Net increase (decrease) in net asset value 
 $(0.65) $(0.03) $(0.03) $0.06  $(0.08)
Net asset value, end of period 
 
$
9.26
  
$
9.91
  
$
9.94
  
$
9.97
  
$
9.91
 
Total return(b) 
  (4.24)%  1.99%  1.28%  2.00%  0.11%
Ratio of net expenses to average net assets 
  
0.89
%
  
0.91
%
  
0.92
%
  
0.93
%
  
0.94
%
Ratio of net investment income (loss) to average net assets 
  
2.25
%
  
2.22
%
  
1.48
%
  
1.27
%
  
0.70
%
Portfolio turnover rate 
  
100
%
  
61
%
  
54
%
  
69
%
  
58
%
Net assets, end of period (in thousands) 
 
$
300,129
  
$
425,928
  
$
623,642
  
$
568,840
  
$
524,030
 
 
  
The Fund was audited by an independent registered public accounting firm other than Ernst & Young LLP. 
(a) 
The per share data presented above is based on the average shares outstanding for the period presented. 
(b) 
Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period and no sales charges. Total return would be reduced if sales charges were taken into account. 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 95

Financial Highlights (continued)
                
 
 Year  Year  Year  Year  Year 
 
 Ended  Ended  Ended  Ended  Ended 
 
 3/31/20  3/31/19  3/31/18  3/31/17*  3/31/16* 
Class C2                
Net asset value, beginning of period 
 
$
9.91
  
$
9.94
  
$
9.97
  
$
9.91
  
$
9.99
 
Increase (decrease) from investment operations: 
                    
Net investment income (loss)(a)  
$
0.21
  
$
0.22
  
$
0.15
  
$
0.13
  
$
0.07
 
Net realized and unrealized gain (loss) on investments   
(0.61
)
  
(0.02
)
  
(0.02
)
  
0.07
   
(0.06
)
Net increase (decrease) from investment operations 
 $(0.40) $0.20  $0.13  $0.20  $0.01 
Distributions to shareowners: 
                    
Net investment income  
$
(0.24
)
 
$
(0.23
)
 
$
(0.16
)
 
$
(0.14
)
 
$
(0.09
)
Net increase (decrease) in net asset value 
 $(0.64) $(0.03) $(0.03) $0.06  $(0.08)
Net asset value, end of period 
 
$
9.27
  
$
9.91
  
$
9.94
  
$
9.97
  
$
9.91
 
Total return(b) 
  (4.13)%  1.98%  1.29%  2.00%  0.11%
Ratio of net expenses to average net assets 
  
0.88
%
  
0.91
%
  
0.92
%
  
0.93
%
  
0.94
%
Ratio of net investment income (loss) to average net assets 
  
2.17
%
  
2.25
%
  
1.47
%
  
1.27
%
  
0.69
%
Portfolio turnover rate 
  
100
%
  
61
%
  
54
%
  
69
%
  
58
%
Net assets, end of period (in thousands) 
 
$
20,982
  
$
8,604
  
$
8,929
  
$
9,834
  
$
10,292
 
 
  
The Fund was audited by an independent registered public accounting firm other than Ernst & Young LLP. 
(a) 
The per share data presented above is based on the average shares outstanding for the period presented. 
(b) 
Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period and no sales charges. Total return would be reduced if sales charges were taken into account. 
 
The accompanying notes are an integral part of these financial statements.
96 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

                
 
 Year  Year  Year  Year  Year 
 
 Ended  Ended  Ended  Ended  Ended 
 
 3/31/20  3/31/19  3/31/18  3/31/17*  3/31/16* 
Class K                
Net asset value, beginning of period 
 
$
9.93
  
$
9.96
  
$
9.99
  
$
9.93
  
$
10.01
 
Increase (decrease) from investment operations: 
                    
Net investment income (loss)(a)  
$
0.28
  
$
0.28
  
$
0.20
  
$
0.19
  
$
0.12
 
Net realized and unrealized gain (loss) on investments   
(0.62
)
  
(0.03
)
  
(0.02
)
  
0.06
   
(0.06
)
Net increase (decrease) from investment operations 
 $(0.34) $0.25  $0.18  $0.25  $0.06 
Distributions to shareowners: 
                    
Net investment income  
$
(0.30
)
 
$
(0.28
)
 
$
(0.21
)
 
$
(0.19
)
 
$
(0.14
)
Net increase (decrease) in net asset value 
 $(0.64) $(0.03) $(0.03) $0.06  $(0.08)
Net asset value, end of period 
 
$
9.29
  
$
9.93
  
$
9.96
  
$
9.99
  
$
9.93
 
Total return(b) 
  (3.60)%  2.54%  1.83%  2.55%  0.64%
Ratio of net expenses to average net assets 
  
0.36
%
  
0.37
%
  
0.38
%
  
0.42
%
  
0.42
%
Ratio of net investment income (loss) to average net assets 
  
2.79
%
  
2.82
%
  
2.03
%
  
1.92
%
  
1.24
%
Portfolio turnover rate 
  
100
%
  
61
%
  
54
%
  
69
%
  
58
%
Net assets, end of period (in thousands) 
 
$
264,405
  
$
274,682
  
$
158,443
  
$
91,666
  
$
5,026
 
 
  
The Fund was audited by an independent registered public accounting firm other than Ernst & Young LLP. 
(a) 
The per share data presented above is based on the average shares outstanding for the period presented. 
(b) 
Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions and the complete redemption of the investment at net asset value at the end of each period. 
 
The accompanying notes are an integral part of these financial statements.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 97

Financial Highlights (continued)
                
 
 Year  Year  Year  Year  Year 
 
 Ended  Ended  Ended  Ended  Ended 
 
 3/31/20  3/31/19  3/31/18  3/31/17*  3/31/16* 
Class Y                
Net asset value, beginning of period 
 
$
9.92
  
$
9.96
  
$
9.99
  
$
9.93
  
$
10.01
 
Increase (decrease) from investment operations: 
                    
Net investment income (loss)(a)  
$
0.27
  
$
0.27
  
$
0.19
  
$
0.17
  
$
0.11
 
Net realized and unrealized gain (loss) on investments   
(0.63
)
  
(0.04
)
  
(0.01
)
  
0.07
   
(0.06
)
Net increase (decrease) from investment operations 
 $(0.36) $0.23  $0.18  $0.24  $0.05 
Distributions to shareowners: 
                    
Net investment income  
$
(0.29
)
 
$
(0.27
)
 
$
(0.21
)
 
$
(0.18
)
 
$
(0.13
)
Net increase (decrease) in net asset value 
 $(0.65) $(0.04) $(0.03) $0.06  $(0.08)
Net asset value, end of period 
 
$
9.27
  
$
9.92
  
$
9.96
  
$
9.99
  
$
9.93
 
Total return(b) 
  (3.78)%  2.37%  1.76%  2.46%  0.54%
Ratio of net expenses to average net assets 
  
0.44
%
  
0.45
%
  
0.46
%
  
0.50
%
  
0.51
%
Ratio of net investment income (loss) to average net assets 
  
2.69
%
  
2.74
%
  
1.94
%
  
1.70
%
  
1.15
%
Portfolio turnover rate 
  
100
%
  
61
%
  
54
%
  
69
%
  
58
%
Net assets, end of period (in thousands) 
 
$
2,990,790
  
$
3,669,866
  
$
2,509,061
  
$
1,768,502
  
$
1,418,468
 
 
  
The Fund was audited by an independent registered public accounting firm other than Ernst & Young LLP. 
(a) 
The per share data presented above is based on the average shares outstanding for the period presented. 
(b) 
Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions and the complete redemption of the investment at net asset value at the end of each period. 
 
The accompanying notes are an integral part of these financial statements.
98 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

Notes to Financial Statements | 3/31/20
1. Organization and Significant Accounting Policies
Pioneer Multi-Asset Ultrashort Income Fund (the “Fund”) is one of three portfolios comprising Pioneer Series Trust X, a Delaware statutory trust. The Fund is registered under the Investment Company Act of 1940 as a diversified, open-end management investment company. The investment objective of the Fund is to seek a high level of current income to the extent consistent with a relatively high level of stability of principal.
The Fund offers five classes of shares designated as Class A, Class C, Class C2, Class K and Class Y shares. Each class of shares represents an interest in the same portfolio of investments of the Fund and has identical rights (based on relative net asset values) to assets and liquidation proceeds. Share classes can bear different rates of class-specific fees and expenses, such as transfer agent and distribution fees. Differences in class-specific fees and expenses will result in differences in net investment income and, therefore, the payment of different dividends from net investment income earned by each class. The Amended and Restated Declaration of Trust of the Fund gives the Board of Trustees the flexibility to specify either per-share voting or dollar-weighted voting when submitting matters for shareholder approval. Under per-share voting, each share of a class of the Fund is entitled to one vote. Under dollar-weighted voting, a shareowner’s voting power is determined not by the number of shares owned, but by the dollar value of the shares on the record date. Each share class has exclusive voting rights with respect to matters affecting only that class, including with respect to the distribution plan for that class. There is no distribution plan for Class K or Class Y shares.
Amundi Pioneer Asset Management, Inc., an indirect, wholly owned subsidiary of Amundi and Amundi’s wholly owned subsidiary, Amundi USA, Inc., serves as the Fund’s investment adviser (the “Adviser”). Amundi Pioneer Distributor, Inc., an affiliate of Amundi Pioneer Asset Management, Inc., serves as the Fund’s distributor (the “Distributor”).
In August 2018, the Securities and Exchange Commission (“SEC”) released a Disclosure Update and Simplification Final Rule. The Final Rule amends Regulation S-X disclosures requirements to conform them to U.S. Generally Accepted Accounting Principles (“U.S. GAAP”) for investment companies. The Fund’s financial statements were prepared in compliance with the new amendments to Regulation S-X.
During March 2017, the Financial Accounting Standards Board (FASB) issued an Accounting Standard Update, ASU 2017-08, Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20), Premium Amortization on Purchased
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Callable Debt Securities (“ASU 2017-08”), which shortens the amortization period for purchased non-contingently callable debt securities held at a premium. ASU 2017-08 specifies that the premium amortization period ends at the earliest call date, for certain purchased non-contingently callable debt securities. ASU 2017-08 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The Fund has adopted ASU 2017-08 as of March 31, 2020. The implementation of ASU 2017-08 did not have a material impact on the Fund’s financial statements.
The Fund is an investment company and follows investment company accounting and reporting guidance under U.S. GAAP. U.S. GAAP requires the management of the Fund to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of income, expenses and gain or loss on investments during the reporting period. Actual results could differ from those estimates.
The following is a summary of significant accounting policies followed by the Fund in the preparation of its financial statements:
A.   Security Valuation
The net asset value of the Fund is computed once daily, on each day the New York Stock Exchange (“NYSE”) is open, as of the close of regular trading on the NYSE.
Fixed-income securities are valued by using prices supplied by independent pricing services, which consider such factors as market prices, market events, quotations from one or more brokers, Treasury spreads, yields, maturities and ratings, or may use a pricing matrix or other fair value methods or techniques to provide an estimated value of the security or instrument. A pricing matrix is a means of valuing a debt security on the basis of current market prices for other debt securities, historical trading patterns in the market for fixed-income securities and/or other factors. Non-U.S. debt securities that are listed on an exchange will be valued at the bid price obtained from an independent third party pricing service. When independent third party pricing services are unable to supply prices, or when prices or market quotations are considered to be unreliable, the value of that security may be determined using quotations from one or more broker-dealers.
Loan interests are valued in accordance with guidelines established by the Board of Trustees at the mean between the last available bid and asked prices from one or more brokers or dealers as obtained from Loan Pricing Corporation, an independent third party pricing service. If price information is not available from Loan Pricing Corporation, or if the price information is deemed to be unreliable, price information will be obtained from an
100 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

alternative loan interest pricing service. If no reliable price quotes are available from either the primary or alternative pricing service, broker quotes will be solicited.
Event-linked bonds are valued at the bid price obtained from an independent third party pricing service. Other insurance-linked securities (including reinsurance sidecars, collateralized reinsurance and industry loss warranties) may be valued at the bid price obtained from an independent pricing service, or through a third party using a pricing matrix, insurance industry valuation models, or other fair value methods or techniques to provide an estimated value of the instrument.
Equity securities that have traded on an exchange are valued by using the last sale price on the principal exchange where they are traded. Equity securities that have not traded on the date of valuation, or securities for which sale prices are not available, generally are valued using the mean between the last bid and asked prices or, if both last bid and asked prices are not available, at the last quoted bid price. Last sale and bid and asked prices are provided by independent third party pricing services. In the case of equity securities not traded on an exchange, prices are typically determined by independent third party pricing services using a variety of techniques and methods.
The value of foreign securities is translated into U.S. dollars based on foreign currency exchange rate quotations supplied by a third party pricing source. Trading in non-U.S. equity securities is substantially completed each day at various times prior to the close of the NYSE. The values of such securities used in computing the net asset value of the Fund’s shares are determined as of such times. The Fund may use a fair value model developed by an independent pricing service to value non-U.S. equity securities.
Repurchase agreements are valued at par. Cash may include overnight time deposits at approved financial institutions.
Securities or loan interests for which independent pricing services or broker-dealers are unable to supply prices or for which market prices and/or quotations are not readily available or are considered to be unreliable are valued by a fair valuation team comprised of certain personnel of the Adviser pursuant to procedures adopted by the Fund’s Board of Trustees. The Adviser’s fair valuation team uses fair value methods approved by the Valuation Committee of the Board of Trustees. The Adviser’s fair valuation team is responsible for monitoring developments that may impact fair valued securities and for discussing and assessing fair values on an ongoing basis, and at least quarterly, with the Valuation Committee of the Board of Trustees.
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Inputs used when applying fair value methods to value a security may include credit ratings, the financial condition of the company, current market conditions and comparable securities. The Fund may use fair value methods if it is determined that a significant event has occurred after the close of the exchange or market on which the security trades and prior to the determination of the Fund’s net asset value. Examples of a significant event might include political or economic news, corporate restructurings, natural disasters, terrorist activity or trading halts. Thus, the valuation of the Fund’s securities may differ significantly from exchange prices, and such differences could be material.
At March 31, 2020, no securities were valued using fair value methods (other than securities valued using prices supplied by independent pricing services, broker-dealers or using a third party insurance industry pricing model).
B.   Investment Income and Transactions
Interest income, including interest on income-bearing cash accounts, is recorded on the accrual basis. Dividend and interest income are reported net of unrecoverable foreign taxes withheld at the applicable country rates and net of income accrued on defaulted securities.
Dividend income is recorded on the ex-dividend date, except that certain dividends from foreign securities where the ex-dividend date may have passed are recorded as soon as the Fund becomes aware of the ex-dividend data in the exercise of reasonable diligence.
Interest and dividend income payable by delivery of additional shares is reclassified as PIK (payment-in-kind) income upon receipt and is included in interest and dividend income, respectively.
Principal amounts of mortgage-backed securities are adjusted for monthly paydowns. Premiums and discounts related to certain mortgage-backed securities are amortized or accreted in proportion to the monthly paydowns. All discounts/premiums on purchase prices of debt securities are accreted/amortized for financial reporting purposes over the life of the respective securities, and such accretion/amortization is included in interest income.
Security transactions are recorded as of trade date. Gains and losses on sales of investments are calculated on the identified cost method for both financial reporting and federal income tax purposes.
102 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

C.   Foreign Currency Translation
The books and records of the Fund are maintained in U.S. dollars. Amounts denominated in foreign currencies are translated into U.S. dollars using current exchange rates.
Net realized gains and losses on foreign currency transactions, if any, represent, among other things, the net realized gains and losses on foreign currency exchange contracts, disposition of foreign currencies and the difference between the amount of income accrued and the U.S. dollars actually received. Further, the effects of changes in foreign currency exchange rates on investments are not segregated on the Statement of Operations from the effects of changes in the market prices of those securities, but are included with the net realized and unrealized gain or loss on investments.
D.   Federal Income Taxes
It is the Fund’s policy to comply with the requirements of the Internal Revenue Code applicable to regulated investment companies and to distribute all of its net taxable income and net realized capital gains, if any, to its shareowners. Therefore, no provision for federal income taxes is required. As of March 31, 2020, the Fund did not accrue any interest or penalties with respect to uncertain tax positions, which, if applicable, would be recorded as an income tax expense on the Statement of Operations. Tax returns filed within the prior three years remain subject to examination by federal and state tax authorities.
The amount and character of income and capital gain distributions to shareowners are determined in accordance with federal income tax rules, which may differ from U.S. GAAP. Distributions in excess of net investment income or net realized gains are temporary over distributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes. Capital accounts within the financial statements are adjusted for permanent book/tax differences to reflect tax character, but are not adjusted for temporary differences.
At March 31, 2020, the Fund reclassified $1,260,555 to increase distributable earnings and $1,260,555 to decrease paid-in capital to reflect permanent book/tax differences. These adjustments have no impact on net assets or the results of operations.
At March 31, 2020, the Fund was permitted to carry forward indefinitely $127,268,187 of short-term losses and $75,764,035 of long-term losses.
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The tax character of distributions paid during the years ended March 31, 2020 and March 31, 2019, were as follows:
       
 
 2020  2019 
Distributions paid from:       
Ordinary income 
 
$
174,573,245
  
$
141,909,242
 
Total  $174,573,245  $141,909,242 
 
The following shows the components of distributable earnings (losses) on a federal income tax basis at March 31, 2020:
    
 
 2020 
Distributable earnings (losses):    
Undistributed ordinary income 
 
$
1,050,217
 
Capital loss carryforward 
  
(203,032,222
)
Current year dividend payable 
  
(1,141,032
)
Unrealized depreciation 
  
(283,923,963
)
Total  $(487,047,000)
 
The difference between book-basis and tax-basis unrealized depreciation is attributable to the tax deferral of losses on wash sales, adjustments relating to event-linked bonds, insurance-linked securities, and the tax treatment of premium and amortization.
E.   Fund Shares
The Fund records sales and repurchases of its shares as of trade date. The Distributor earned $0 in underwriting commissions on the sale of Class A shares during the year ended March 31, 2020.
F.   Class Allocations
Income, common expenses and realized and unrealized gains and losses are calculated at the Fund level and allocated daily to each class of shares based on its respective percentage of adjusted net assets at the beginning of the day.
Distribution fees are calculated based on the average daily net asset value attributable to Class A, Class C and Class C2 shares of the Fund, respectively (see Note 4). Class K and Class Y shares do not pay distribution fees. All expenses and fees paid to the Fund’s transfer agent, for its services are allocated among the classes of shares based on the number of accounts in each class and the ratable allocation of related out-of-pocket expenses (see Note 3).
The Fund declares as daily dividends substantially all of its net investment income. All dividends are paid on a monthly basis. Short-term capital gain distributions, if any, may be declared with the daily dividends. Distributions to shareowners are recorded as of the ex-dividend date. Distributions paid by the Fund with respect to each class of shares are calculated in the same
104 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

manner and at the same time except that net investment income dividends to Class A, Class C, Class C2, Class K and Class Y shares can reflect different transfer agent and distribution expense rates.
G.   Risks
The value of securities held by the Fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political or regulatory conditions, recessions, the spread of infectious illness or other public health issues, inflation, changes in interest rates, lack of liquidity in the bond markets or adverse investor sentiment. In the past several years, financial markets have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. These conditions may continue, recur, worsen or spread.
At times, the Fund’s investments may represent industries or industry sectors that are interrelated or have common risks, making the Fund more susceptible to any economic, political, or regulatory developments or other risks affecting those industries and sectors. The Fund’s investments in foreign markets and countries with limited developing markets may subject the Fund to a greater degree of risk than investments in a developed market. These risks include disruptive political or economic conditions and the imposition of adverse governmental laws or currency exchange restrictions.
The Fund invests in below-investment-grade (high-yield) debt securities and preferred stocks. Some of these high-yield securities may be convertible into equity securities of the issuer. Debt securities rated below-investment-grade are commonly referred to as “junk bonds” and are considered speculative. These securities involve greater risk of loss, are subject to greater price volatility, and are less liquid, especially during periods of economic uncertainty or change, than higher rated debt securities.
With the increased use of technologies such as the Internet to conduct business, the Fund is susceptible to operational, information security and related risks. While the Fund’s Adviser has established business continuity plans in the event of, and risk management systems to prevent, limit or mitigate, such cyber-attacks, there are inherent limitations in such plans and systems, including the possibility that certain risks have not been identified. Furthermore, the Fund cannot control the cybersecurity plans and systems put in place by service providers to the Fund such as Brown Brothers Harriman & Co., the Fund’s custodian and accounting agent, and DST Asset Manager Solutions, Inc., the Fund’s transfer agent. In addition, many beneficial owners of Fund shares hold them through accounts at broker-dealers, retirement platforms and other financial market participants over which neither the Fund nor Amundi Pioneer exercises control. Each of these may in turn rely on service providers to them, which are also subject to the
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 105

risk of cyber-attacks. Cybersecurity failures or breaches at Amundi Pioneer or the Fund’s service providers or intermediaries have the ability to cause disruptions and impact business operations, potentially resulting in financial losses, interference with the Fund’s ability to calculate its net asset value, impediments to trading, the inability of Fund shareowners to effect share purchases, redemptions or exchanges or receive distributions, loss of or unauthorized access to private shareowner information and violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, or additional compliance costs. Such costs and losses may not be covered under any insurance. In addition, maintaining vigilance against cyber-attacks may involve substantial costs over time, and system enhancements may themselves be subject to cyber-attacks.
The Fund’s prospectus contains unaudited information regarding the Fund’s principal risks. Please refer to that document when considering the Fund’s principal risks.
H.   Insurance-Linked Securities (“ILS”)
The Fund invests in ILS. The Fund could lose a portion or all of the principal it has invested in an ILS, and the right to additional interest or dividend payments with respect to the security, upon the occurrence of one or more trigger events, as defined within the terms of an insurance-linked security. Trigger events, generally, are hurricanes, earthquakes, or other natural events of a specific size or magnitude that occur in a designated geographic region during a specified time period, and/or that involve losses or other metrics that exceed a specific amount. There is no way to accurately predict whether a trigger event will occur, and accordingly, ILS carry significant risk. The Fund is entitled to receive principal, and interest and/or dividend payments so long as no trigger event occurs of the description and magnitude specified by the instrument. In addition to the specified trigger events, ILS may expose the Fund to other risks, including but not limited to issuer (credit) default, adverse regulatory or jurisdictional interpretations and adverse tax consequences.
The Fund’s investments in ILS may include event-linked bonds. ILS also may include special purpose vehicles (“SPVs”) or similar instruments structured to comprise a portion of a reinsurer’s catastrophe-oriented business, known as quota share instruments (sometimes referred to as reinsurance sidecars), or to provide reinsurance relating to specific risks to insurance or reinsurance companies through a collateralized instrument, known as collateralized reinsurance. Structured reinsurance investments also may include industry loss warranties (“ILWs”). A traditional ILW takes the form of a bilateral reinsurance contract, but there are also products that take the form of derivatives, collateralized structures, or exchange-traded instruments.
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Where the ILS are based on the performance of underlying reinsurance contracts, the Fund has limited transparency into the individual underlying contracts, and therefore must rely upon the risk assessment and sound underwriting practices of the issuer. Accordingly, it may be more difficult for the Adviser to fully evaluate the underlying risk profile of the Fund’s structured reinsurance investments, and therefore the Fund’s assets are placed at greater risk of loss than if the Adviser had more complete information. Structured reinsurance instruments generally will be considered illiquid securities by the Fund. These securities may be difficult to purchase, sell or unwind. Illiquid securities also may be difficult to value. If the Fund is forced to sell an illiquid asset, the Fund may be forced to sell at a loss.
I.    Repurchase Agreements
Repurchase agreements are arrangements under which the Fund purchases securities from a broker-dealer or a bank, called the counterparty, upon the agreement of the counterparty to repurchase the securities from the Fund at a later date, and at a specific price, which is typically higher than the purchase price paid by the Fund. The securities purchased serve as the Fund’s collateral for the obligation of the counterparty to repurchase the securities. The value of the collateral, including accrued interest, is required to be equal to or in excess of the repurchase price. The collateral for all repurchase agreements is held in safekeeping in the customer-only account of the Fund’s custodian or a sub-custodian of the Fund. The Adviser is responsible for determining that the value of the collateral remains at least equal to the repurchase price. In the event of a default by the counterparty, the Fund is entitled to sell the securities, but the Fund may not be able to sell them for the price at which they were purchased, thus causing a loss to the Fund. Additionally, if the counterparty becomes insolvent, there is some risk that the Fund will not have a right to the securities, or the immediate right to sell the securities.
Open repurchase agreements at March 31, 2020, are disclosed in the Schedule of Investments.
2. Management Agreement
The Adviser manages the Fund’s portfolio. Management fees are paid monthly and are calculated daily at the annual rate of 0.35% of the Fund’s average daily net assets up to $1 billion, 0.30% of the next $4 billion of the Fund’s average daily net assets, 0.25% of the next $2.5 billion of the Fund’s average daily net assets and 0.20% of the Fund’s average daily net assets over $7.5 billion. For the year ended March 31, 2020, the effective management fee was equivalent to 0.30% of the Fund’s average daily net assets.
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In addition, under the management and administration agreements, certain other services and costs, including accounting, regulatory reporting and insurance premiums, are paid by the Fund as administrative reimbursements. Included in “Due to affiliates” reflected on the Statement of Assets and Liabilities is $229,942 in management fees, administrative costs and certain other reimbursements payable to the Adviser at March 31, 2020.
3. Transfer Agent
DST Asset Manager Solutions, Inc. serves as the transfer agent to the Fund at negotiated rates. Transfer agent fees and payables shown on the Statement of Operations and the Statement of Assets and Liabilities, respectively, include sub-transfer agent expenses incurred through the Fund’s omnibus relationship contracts.
In addition, the Fund reimbursed the transfer agent for out-of-pocket expenses incurred by the transfer agent related to shareowner communications activities such as proxy and statement mailings, and outgoing phone calls. For the year ended March 31, 2020, such out-of-pocket expenses by class of shares were as follows:
    
Shareowner Communications:    
Class A 
 
$
25,257
 
Class C 
  
12,343
 
Class C2 
  
244
 
Class K 
  
508
 
Class Y 
  
122,899
 
Total  $161,251 
 
4. Distribution Plan
The Fund has adopted a distribution plan (the “Plan”) pursuant to Rule 12b-1 of the Investment Company Act of 1940 with respect to its Class A, Class C and Class C2 shares. Pursuant to the Plan, the Fund pays the Distributor 0.20% of the average daily net assets attributable to Class A shares as compensation for personal services and/or account maintenance services or distribution services with regard to Class A shares. Pursuant to the Plan, the Fund also pays the Distributor 0.50% of the average daily net assets attributable to Class C and Class C2 shares. The fee for Class C and Class C2 shares consists of a 0.25% service fee and a 0.25% distribution fee paid as compensation for personal services and/or account maintenance services or distribution services with regard to Class C and Class C2 shares. Included in “Due to affiliates” reflected on the Statement of Assets and Liabilities is $65,935 in distribution fees payable to the Distributor at March 31, 2020.
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In addition, redemptions of Class A and Class C2 shares may be subject to a contingent deferred sales charge (“CDSC”). A CDSC of 1.00% may be imposed on redemptions of certain net asset value purchases of Class A shares within 12 months of purchase. Redemptions of Class C2 shares redemptions of shares within 12 months of purchase are subject to a CDSC of 1.00%, based on the lower of cost or market value of shares being redeemed. Shares purchased as part of an exchange remain subject to any CDSC that applied to the original purchase of those shares. There is no CDSC for Class C, Class K and Class Y shares. Proceeds from the CDSCs are paid to the Distributor. For the year ended March 31, 2020, CDSCs in the amount of $10,115 were paid to the Distributor.
5. Line of Credit Facility
The Fund, along with certain other funds in the Pioneer Family of Funds (the “Funds”), participates in a committed, unsecured revolving line of credit facility. Borrowings are used solely for temporary or emergency purposes. The Fund may borrow up to the lesser of the amount available under the credit facility or the limits set for borrowing by the Fund’s prospectus and the 1940 Act. Effective March 11, 2020, the Fund participates in a facility that is in the amount of $300 million. Prior to March 11, 2020, the Fund participated in a facility in the amount of $250 million. Under such facility, depending on the type of loan, interest on borrowings is payable at the London Interbank Offered Rate (“LIBOR”) plus a credit spread. The Fund also pays an annual commitment fee to participate in a credit facility. The commitment fee is allocated among participating Funds based on an allocation schedule set forth in the credit agreement. For the year ended March 31, 2020, the Fund had no borrowings under the credit facility.
6. Unfunded Loan Commitments
The Fund may enter into unfunded loan commitments. Unfunded loan commitments may be partially or wholly unfunded. During the contractual period, the Fund is obliged to provide funding to the borrower upon demand. A fee is earned by the Fund on the unfunded commitment and is recorded as interest income on the Statement of Operations.
As of March 31, 2020, the Fund had the following unfunded loan commitments outstanding:
             
 
          Unrealized 
 
          Appreciation/ 
Loan  Principal  Cost  Value  (Depreciation) 
Gbt US LLC 
 
$
638,053
  
$
625,403
  
$
558,296
  
$
(67,107
)
NMN Holdings III Corp. 
  
323,878
   
323,231
   
268,009
   
(55,222
)
Total Value  $961,931  $948,634  $826,305  $(122,329)
 
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7. Subsequent Event
COVID-19
The respiratory illness COVID-19 caused by a novel coronavirus has resulted in a global pandemic and major disruption to economies and markets around the world, including the United States. Global financial markets have experienced extreme volatility and severe losses, and trading in many instruments has been disrupted. Liquidity for many instruments has been greatly reduced for periods of time. Some interest rates are very low and in some cases yields are negative. Some sectors of the economy and individual issuers have experienced particularly large losses. These circumstances may continue for an extended period of time, and may continue to affect adversely the value and liquidity of the Fund’s investments. The ultimate economic fallout from the pandemic, and the long-term impact on economies, markets, industries and individual issuers, are not known. Governments and central banks, including the Federal Reserve in the U.S., have taken extraordinary and unprecedented actions to support local and global economies and the financial markets. These actions have resulted in significant expansion of public debt, including in the U.S. The impact of these measures, and whether they will be effective to mitigate the economic and market disruption, will not be known for some time. The consequences of high public debt, including its future impact on the economy and securities markets, likewise may not be known for some time.
110 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

Report of Independent Registered Public Accounting Firm


To the Board of Trustees of Pioneer Series Trust X and the Shareholders of
Pioneer Multi-Asset Ultrashort Income Fund:
Opinion on the Financial Statements
We have audited the accompanying statement of assets and liabilities of Pioneer Multi-Asset Ultrashort Income Fund (the “Fund”) (one of the funds constituting Pioneer Series Trust X (the “Trust”)), including the schedule of investments, as of March 31, 2020, and the related statement of operations for the year then ended, the statements of changes in net assets for each of the two years in the period then ended, the financial highlights for each of the three years in the period then ended and the related notes (collectively referred to as the “financial statements”). The financial highlights for the periods ended March 31, 2016 and March 31, 2017 were audited by another independent registered public accounting firm whose report, dated May 26, 2017, expressed an unqualified opinion on those financial highlights. In our opinion, the financial statements present fairly, in all material respects, the financial position of Pioneer Multi-Asset Ultrashort Income Fund (one of the funds constituting Pioneer Series Trust X) at March 31, 2020, the results of its operations for the year then ended, the changes in its net assets for each of the two years in the period then ended, and its financial highlights for each of the three years in the period then ended in conformity with U.S. generally accepted accounting principles.
Basis for Opinion
These financial statements are the responsibility of the Trust’s management. Our responsibility is to express an opinion on the Fund’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (“PCAOB”) and are required to be independent with respect to the Trust in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.
We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Trust is not required to have, nor were we engaged to perform, an audit of the Trust’s internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting, but not for the purpose of expressing an opinion on the effectiveness of the Trust’s internal control over financial reporting. Accordingly, we express no such opinion.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 111

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our procedures included confirmation of securities owned as of March 31, 2020, by correspondence with the custodian and brokers. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.
We have served as the auditor of one or more Amundi Pioneer investment companies since 2017.
Boston, Massachusetts
May 29, 2020
112 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

ADDITIONAL INFORMATION (unaudited)
Qualified interest income is exempt from nonresident alien (NRA) tax withholding. The percentage of the Fund’s ordinary income distributions derived from qualified interest income was 76.89%.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 113

Trustees, Officers and Service Providers


Investment Adviser and Administrator
Amundi Pioneer Asset Management, Inc.


Custodian and Sub-Administrator
Brown Brothers Harriman & Co.


Independent Registered Public Accounting Firm
Ernst & Young LLP


Principal Underwriter
Amundi Pioneer Distributor, Inc.


Legal Counsel
Morgan, Lewis & Bockius LLP


Transfer Agent
DST Asset Manager Solutions, Inc.
Proxy Voting Policies and Procedures of the Fund are available without charge, upon request, by calling our toll free number (1-800-225-6292). Information regarding how the Fund voted proxies relating to portfolio securities during the most recent 12-month period ended June 30 is publicly available to shareowners at www.amundipioneer.com/us. This information is also available on the Securities and Exchange Commission’s web site at www.sec.gov.
Trustees and Officers
The Fund’s Trustees and officers are listed below, together with their principal occupations and other directorships they have held during at least the past five years. Trustees who are interested persons of the Fund within the meaning of the 1940 Act are referred to as Interested Trustees. Trustees who are not interested persons of the Fund are referred to as Independent Trustees. Each of the Trustees serves as a Trustee of each of the 45 U.S. registered investment portfolios for which Amundi Pioneer serves as investment adviser (the “Pioneer Funds”). The address for all Trustees and all officers of the Fund is 60 State Street, Boston, Massachusetts 02109.
The Statement of Additional Information of the Fund includes additional information about the Trustees and is available, without charge, upon request, by calling 1-800-225-6292.
114 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

Independent Trustees
    
Name, Age and Position Term of Office and 
 
Other Directorships 
Held With the Fund Length of Service Principal Occupation Held by Trustee 
Thomas J. Perna (68) 
Chairman of the Board 
and Trustee
Trustee since 2011. Serves until a successor trustee is elected or earlier retirement 
or removal.
Private investor (2004 – 2008 and 2013 – present); Chairman (2008 – 2013) and Chief Executive Officer (2008 – 2012), Quadriserv, Inc. (technology products for securities lending industry); and Senior Executive Vice President, The Bank of New York (financial and securities services) (1986 – 2004) 
 
Director, Broadridge Financial Solutions, Inc. (investor communications and securities processing provider for financial services industry) (2009 – present); Director, Quadriserv, Inc. (2005 – 2013); and Commissioner, New Jersey State Civil Service Commission (2011 – 2015) 
John E. Baumgardner, Jr. (68) 
Trustee
Trustee since 2019. Serves until a successor trustee is elected or earlier retirement 
or removal. 
Of Counsel (2019 – present), Partner (1983-2018), Sullivan & Cromwell LLP (law firm).
Chairman, The Lakeville Journal Company, LLC, (privately-held community newspaper group) (2015-present) 
Diane Durnin (63) 
Trustee
Trustee since 2019. Serves until a successor trustee is elected or earlier retirement 
or removal. 
 
Managing Director - Head of Product Strategy and Development, BNY Mellon Investment Management (2012-2018); Vice Chairman – The Dreyfus Corporation (2005 – 2018): Executive Vice President Head of Product, BNY Mellon Investment Management (2007-2012); Executive Director- Product Strategy, Mellon Asset Management (2005-2007); Executive Vice President Head of Products, Marketing and Client Service, Dreyfus Corporation (2000-2005); and Senior Vice President Strategic Product and Business Development, Dreyfus Corporation (1994-2000) 
None
 
Benjamin M. Friedman (75) 
Trustee
Trustee since 2011. Serves until a successor trustee is elected or earlier retirement 
or removal. 
William Joseph Maier Professor of Political Economy, Harvard University (1972 – present) 
Trustee, Mellon Institutional Funds Investment Trust and Mellon Institutional Funds Master Portfolio (oversaw 17 portfolios in fund complex) (1989 - 2008) 
 
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/2 115

Independent Trustees (continued)
    
Name, Age and Position Term of Office and 
 
Other Directorships 
Held With the Fund Length of Service Principal Occupation Held by Trustee 
Lorraine H. Monchak (64) 
Trustee 
 
Trustee since 2017. 
(Advisory Trustee from 
2014 - 2017). Serves until a successor trustee is elected or earlier retirement or removal. 
 
Chief Investment Officer, 1199 SEIU Funds (healthcare workers union pension funds) (2001 – present); Vice President – International Investments Group, American International Group, Inc. (insurance company) (1993 – 2001); Vice President – Corporate Finance and Treasury Group, Citibank, N.A. (1980 – 1986 and 1990 – 1993); Vice President – Asset/Liability Management Group, Federal Farm Funding Corporation (government-sponsored issuer of debt securities) (1988 – 1990); Mortgage Strategies Group, Shearson Lehman Hutton, Inc. (investment bank) (1987 – 1988); and Mortgage Strategies Group, Drexel Burnham Lambert, Ltd. (investment bank) (1986 – 1987)
None 
 
 
Marguerite A. Piret (71) 
Trustee 
 
Trustee since 2011. Serves until a successor trustee is elected or earlier retirement 
or removal. 
Chief Financial Officer, American Ag Energy, Inc. (controlled environment and agriculture company) (2016 – present); and President and Chief Executive Officer, Metric Financial Inc. (formerly known as Newbury Piret Company) (investment banking firm) (1981 – 2019) 
Director ofNew America High Income Fund, Inc. (closed-end investment company) (2004 – present); and Member, Board of Governors, Investment Company Institute (2000 – 2006) 
Fred J. Ricciardi (73) 
Trustee 
 
Trustee since 2014. Serves until a successor trustee is elected or earlier retirement 
or removal. 
 
Consultant (investment company services) (2012 – present); Executive Vice President, BNY Mellon (financial and investment company services) (1969 – 2012); Director, BNY International Financing Corp. (financial services) (2002 – 2012); Director, Mellon Overseas Investment Corp. (financial services) (2009 – 2012); Director, Financial Models (technology) (2005-2007); Director, BNY Hamilton Funds, Ireland (offshore investment companies) (2004-2007); Chairman/Director, AIB/BNY Securities Services, Ltd., Ireland (financial services) (1999-2006); and Chairman, BNY Alternative Investment Services, Inc. (financial services) (2005-2007) 
None 
 
 
 
116 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

Interested Trustees
    
Name, Age and Position Term of Office and 
 
Other Directorships 
Held With the Fund Length of Service Principal Occupation Held by Trustee 
Lisa M. Jones (58)* 
Trustee, President and 
Chief Executive Officer 
 
Trustee since 2017. Serves until a successor trustee is elected or earlier retirement 
or removal 
Director, CEO and President of Amundi Pioneer Asset Management USA, Inc. (since September 2014); Director, CEO and President of Amundi Pioneer Asset Management, Inc. (since September 2014); Director, CEO and President of Amundi Pioneer Distributor, Inc. (since September 2014); Director, CEO and President of Amundi Pioneer Institutional Asset Management, Inc. (since September 2014); Chair, Amundi Pioneer Asset Management USA, Inc., Amundi Pioneer Distributor, Inc. and Amundi Pioneer Institutional Asset Management, Inc. (September 2014 – 2018); Managing Director, Morgan Stanley Investment Management (2010 – 2013); Director of Institutional Business, CEO of International, Eaton Vance Management (2005 – 2010); and Director of Amundi USA, Inc. (since 2017) 
None 
 
Kenneth J. Taubes (62)* 
Trustee 
 
Trustee since 2014. Serves until a successor trustee is elected or earlier retirement 
or removal 
 
Director and Executive Vice President (since 2008) and Chief Investment Officer, U.S. (since 2010) of Amundi Pioneer Asset Management USA, Inc.; Director and Executive Vice President and Chief Investment Officer, U.S. of Amundi Pioneer (since 2008); Executive Vice President and Chief Investment Officer, U.S. of Amundi Pioneer Institutional Asset Management, Inc. (since 2009); Portfolio Manager of Amundi Pioneer (since 1999); and Director of Amundi USA, Inc. (since 2017) 
None 
 
 
* Ms. Jones and Mr. Taubes are Interested Trustees because they are officers or directors of the Fund’s investment adviser and certain of its affiliates.
Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20 117

Fund Officers
    
Name, Age and Position Term of Office and 
 
Other Directorships 
Held With the Fund Length of Service Principal Occupation Held by Officer 
Christopher J. Kelley (55) 
Secretary and Chief 
Legal Officer 
 
Since 2011. Serves at the discretion of the Board 
 
Vice President and Associate General Counsel of Amundi Pioneer since January 2008; Secretary and Chief Legal Officer of all of the Pioneer Funds since June 2010; Assistant Secretary of all of the Pioneer Funds from September 2003 to May 2010; and Vice President and Senior Counsel of Amundi Pioneer from July 2002 to December 2007 
None 
Carol B. Hannigan (59) 
Assistant Secretary 
 
Since 2011. Serves at the discretion of the Board 
Fund Governance Director of Amundi Pioneer since December 2006 and Assistant Secretary of all the Pioneer Funds since June 2010; Manager – Fund Governance of Amundi Pioneer from December 2003 to November 2006; and Senior Paralegal of Amundi Pioneer from January 2000 to November 2003 
None
Thomas Reyes (57) 
Assistant Secretary 
Since 2011. Serves at the discretion of the Board 
Assistant General Counsel of Amundi Pioneer since May 2013 and Assistant Secretary of all the Pioneer Funds since June 2010; and Counsel of Amundi Pioneer from June 2007 to May 2013
None 
 
Mark E. Bradley (60) 
Treasurer and Chief 
Financial and Accounting 
Officer 
Since 2011. Serves at the discretion of the Board 
 
Vice President – Fund Treasury of Amundi Pioneer; Treasurer of all of the Pioneer Funds since March 2008; Deputy Treasurer of Amundi Pioneer from March 2004 to February 2008; and Assistant Treasurer of all of the Pioneer Funds from March 2004 to February 2008 
None 
Luis I. Presutti (55) 
Assistant Treasurer 
Since 2011. Serves at the discretion of the Board 
Director – Fund Treasury of Amundi Pioneer; and Assistant Treasurer of all of the Pioneer Funds 
None 
Gary Sullivan (62) 
Assistant Treasurer 
Since 2011. Serves at the discretion of the Board 
Senior Manager – Fund Treasury of Amundi Pioneer; and Assistant Treasurer of all of the Pioneer Funds 
None 
 
118 Pioneer Multi-Asset Ultrashort Income Fund | Annual Report | 3/31/20

    
Name, Age and Position Term of Office and 
 
Other Directorships 
Held With the Fund Length of Service Principal Occupation Held by Officer 
Antonio Furtado (38) 
Assistant Treasurer 
Since 2020. Serves at the discretion of the Board 
Fund Oversight Manager – Fund Treasury of Amundi Pioneer; and Assistant Treasurer of all of the Pioneer Funds 
None 
John Malone (48) 
Chief Compliance Officer 
 
Since 2018. Serves at the discretion of the Board 
 
Managing Director, Chief Compliance Officer of Amundi Pioneer Asset Management; Amundi Pioneer Institutional Asset Management, Inc.; and the Pioneer Funds since September 2018; and Chief Compliance Officer of Amundi Pioneer Distributor, Inc. since January 2014. 
None 
 
Kelly O’Donnell (49) 
Anti-Money Laundering 
Officer 
Since 2011. Serves at the discretion of the Board 
Vice President – Amundi Pioneer Asset Management; and Anti-Money Laundering Officer of all the Pioneer Funds since 2006 
None 
 
 
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How to Contact Amundi Pioneer
We are pleased to offer a variety of convenient ways for you to contact us for assistance or information.
   
Call us for: 
 
 
Account Information, including existing accounts, 
 
new accounts, prospectuses, applications 
 
and service forms 
 
1-800-225-6292 
   
FactFoneSM for automated fund yields, prices, 
 
account information and transactions 
1-800-225-4321 
  
Retirement plans information 1-800-622-0176 
 
Write to us: 
 
 
Amundi Pioneer 
 
 
P.O. Box 219427 
 
 
Kansas City, MO 64121-9427 
 
 
   
Our toll-free fax 
 
1-800-225-4240 
   
Our internet e-mail address us.askamundipioneer@amundipioneer.com 
(for general questions about Amundi Pioneer only) 
 
 
Visit our web site: www.amundipioneer.com/us 
 
 
This report must be preceded or accompanied by a prospectus.
The Fund files a complete schedule of portfolio holdings with the Securities and Exchange Commission for the first and third quarters of each fiscal year as an exhibit to its reports on Form N-PORT. Shareholders may view the filed Form N-PORT by visiting the Commission’s web site at https://www.sec.gov.



Amundi Pioneer Asset Management, Inc.
60 State Street
Boston, MA 02109
www.amundipioneer.com/us

Securities offered through Amundi Pioneer Funds Distributor, Inc.
60 State Street, Boston, MA 02109
Underwriter of Pioneer Mutual Funds, Member SIPC
© 2020 Amundi Pioneer Asset Management 25671-08-0520






Pioneer Fundamental


Growth Fund


Annual Report | March 31, 2020
  
Ticker Symbols: 
Class A 
PIGFX 
Class C 
FUNCX 
Class K 
PFGKX 
Class R 
PFGRX 
Class Y 
FUNYX 
 
Beginning in March 2021, as permitted by regulations adopted by the Securities and Exchange Commission, paper copies of the Fund’s shareholder reports like this one will no longer be sent by mail, unless you specifically request paper copies of the reports from the Fund or from your financial intermediary, such as a broker-dealer, bank or insurance company. Instead, the reports will be made available on the Fund’s website, and you will be notified by mail each time a report is posted and provided with a website link to access the report.
If you already elected to receive shareholder reports electronically, you will not be affected by this change and you need not take any action. You may elect to receive shareholder reports and other communications electronically by contacting your financial intermediary or, if you invest directly with the Fund, by calling 1-800-225-6292.
You may elect to receive all future reports in paper free of charge. If you invest directly with the Fund, you can inform the Fund that you wish to continue receiving paper copies of your shareholder reports by calling 1-800-225-6292. If you invest through a financial intermediary, you can contact your financial intermediary to request that you continue to receive paper copies of your shareholder reports. Your election to receive reports in paper will apply to all funds held in your account if you invest through your financial intermediary or all funds held within the Pioneer Fund complex if you invest directly.





visit us: www.amundipioneer.com/us



Table of Contents
  
 
Pioneer Fundamental Growth Fund | Annual Report | 3/31/20 1


President’s Letter
Dear Shareholders,
The new decade has arrived delivering a first quarter that will go down in the history books. The beginning of the year seemed to extend the positive market environment of 2019 and then, March roared in like a lion and the COVID-19 pandemic became a global crisis impacting lives and life as we know it. The impact on the global economy from the COVID-19 virus pandemic, while currently unknown, is likely to be considerable. It is clear that several industries have already felt greater effects than others. And the markets, which do not thrive on uncertainty, have been volatile. Our business continuity plan was implemented given the new COVID-19 guidelines, and most of our employees are working remotely. To date, our operating environment has faced no interruption. I am proud of the careful planning that has taken place and confident we can maintain this environment for as long as is prudent. History in the making for a company that first opened its doors way back in 1928.
Since 1928, Amundi Pioneer’s investment process has been built on a foundation of fundamental research and active management, principles which have guided our investment decisions for more than 90 years. We believe active management – that is, making active investment decisions – can help mitigate the potential risks during periods of market volatility. As the early days of 2020 have reminded us, in today’s global economy, investment risk can materialize from a number of factors, including a slowing economy, changing U.S. Federal Reserve policy, oil price shocks, political and geopolitical factors and, unfortunately, major public health concerns such as a viral pandemic.
At Amundi Pioneer, active management begins with our own fundamental, bottom-up research process. Our team of dedicated research analysts and portfolio managers analyze each security under consideration, communicating directly with the management teams of the companies issuing the securities and working together to identify those securities that best meet our investment criteria for our family of funds. Our risk management approach begins with each and every security, as we strive to carefully understand the potential opportunity, while considering any and all risk factors.
2 Pioneer Fundamental Growth Fund | Annual Report | 3/31/20

Today, as investors, we have many options. It is our view that active management can serve shareholders well, not only when markets are thriving, but also during periods of market stress. As you consider your long-term investment goals, we encourage you to work with your financial advisor to develop an investment plan that paves the way for you to pursue both your short-term and long-term goals.
We remain confident that the current crisis, like others in human history, will pass, and we greatly appreciate the trust you have placed in us and look forward to continuing to serve you in the future.
Sincerely,
Lisa M. Jones
Head of the Americas, President and CEO of U.S.
Amundi Pioneer Asset Management USA, Inc.
March 31, 2020
Any information in this shareowner report regarding market or economic trends or the factors influencing the Fund’s historical or future performance are statements of opinion as of the date of this report. Past performance is no guarantee of future results.
Pioneer Fundamental Growth Fund | Annual Report | 3/31/20 3

Portfolio Management Discussion | 3/31/20
The decade-long bull market for U.S. equities drew to a close late in the 12-month period ended March 31, 2020, as the COVID-19 virus pandemic caused much of the global economy to shut down and sent stocks into a bear-market decline. However, markets recovered sharply at the end of the period from their worst levels, offsetting some of the losses for the full fiscal year. In the following interview, Andrew Acheson and Paul Cloonan discuss the factors that affected the performance of Pioneer Fundamental Growth Fund during the 12-month period. Mr. Acheson, Managing Director, Director of Growth, U.S., and a portfolio manager at Amundi Pioneer Asset Management, Inc. (Amundi Pioneer), and Mr. Cloonan, a senior vice president and a portfolio manager at Amundi Pioneer, are responsible for the day-to-day management of the Fund.
Q How did the Fund perform during the 12-month period ended March 31, 2020?
A Pioneer Fundamental Growth Fund’s Class A shares returned -2.17% at net asset value during the 12-month period ended March 31, 2020, while the Fund’s benchmark, the Russell 1000 Growth Index (the Russell Index), returned 0.91%. During the same period, the average return of the 1,358 mutual funds in Morningstar’s Large Growth Funds category was -3.72%.
Q How would you describe the investment environment for domestic equity stocks during the 12-month period ended March 31, 2020?
A The 12-month period was extremely volatile for U.S. equities. Throughout the early part of the period, trade tensions between the U.S. and China increased dramatically, leading to higher tariffs and heightened uncertainty about the global economic growth outlook. The U.S. Federal Reserve (Fed) responded to a less-robust growth outlook in July 2019 with its first interest-rate reduction in a decade, but stock markets remained choppy as trade negotiations started and stopped throughout much of 2019. By December, however, the U.S. and China had announced a “phase one” trade deal, sending domestic equities to record highs. The market rally proved short-lived, however, as the growing COVID-19 pandemic led to virus-containment measures that essentially brought the global economy to a halt.
Stocks began moving sharply lower in mid-February 2020 as investors fled riskier assets for so-called “safe haven” alternatives such as Treasuries. The Fed responded by cutting its benchmark short-term interest rate to zero and reviving 2008/2009 financial crisis-era asset purchase and credit-support
4 Pioneer Fundamental Growth Fund | Annual Report | 3/31/20

programs. Meanwhile, the U.S. government passed a $2.2 trillion stimulus package. Those aggressive fiscal and monetary policy measures allowed stocks to recover, to a certain degree, and move up from their worst levels as the 12-month period drew to a close.
Somewhat counterintuitively, the best-performing sector during the 12-month period was information technology, as many tech companies once again showed the ability to prosper without broad-based economic growth. Meanwhile, cyclical stocks performed poorly, with the industrials and materials sectors declining the most.
Q How would you characterize the Fund’s positioning and how the positioning affected benchmark-relative performance during the 12-month period ended March 31, 2020?
A During the 12-month period, we maintained our traditional discipline of focusing the Fund’s investments on shares of what we believe to be higher-quality corporations with stable businesses, sustainable competitive advantages, secular growth opportunities, reasonable valuations, and steady earnings. Given our focus on trying to mitigate risk in the portfolio, the Fund’s performance has typically lagged the benchmark’s performance during periods of strong market appreciation. That was especially the case in the fourth quarter of 2019 and early in 2020, as investors favored high-growth, high-valuation stocks in which the Fund was underweight due to our valuation discipline in managing the portfolio.
Conversely, the Fund has typically outperformed the benchmark during market declines. However, during the market’s drop from late February to late March of this year, the Fund performed only roughly in line with the Russell Index. The nature of the recent market decline was far different from the typical sell-off. In the past, when weakening economic conditions have caused stock markets to fall, the Fund’s strict quality requirements have typically led to less volatile performance. In addition, our portfolio construction process attempts to limit risk at the security, sector, and Fund levels. The result is a portfolio containing stocks of companies that have tended to be profitable on average and that have had lower-than-average debt levels, which are the stocks investors have often turned to during uncertain times, due to their more predictable nature. During the most recent market slump in the wake of COVID-19, that was not uniformly the case, as some stocks that have historically been defensive - meaning that they have declined much less than the overall equity markets during past downturns - actually fell much more sharply than the Russell Index toward the end of the 12-month period.
Pioneer Fundamental Growth Fund | Annual Report | 3/31/20 5

Q Which individual portfolio positions detracted from the Fund’s performance relative to the benchmark Russell Index during the 12-month period ended March 31, 2020?
A To illustrate the points we made earlier, three portfolio holdings in particular that have traditionally behaved defensively, but underperformed during the recent market decline and detracted from the Fund’s benchmark-relative returns over the 12-month period, were Ecolab, O’Reilly Auto Parts, and Ross Stores.
Ecolab provides cleaning and sanitizing solutions as well as water treatment equipment. The business has historically generated steady growth over time and often has proved resilient during recessions. The stock outperformed the Russell Index by 15 percentage points during the last major recession in 2008/2009, and by 9 percentage points during the late-2018 market correction. During the pandemic-induced decline towards the end of the 12-month period, however, Ecolab actually underperformed the Russell Index by nearly 9 percentage points, primarily due to the market’s concerns about declining sales to the struggling restaurant and hotel industries that use the company’s products. We do not believe the decline in the stock price was warranted, as we view Ecolab as exceptionally well positioned to potentially benefit from society’s increased focus on sanitization going forward as a result of the COVID-19 virus.
O’Reilly, a leading auto parts retailer, has been generating high returns on capital and has had a competitive advantage based on parts availability that has been difficult for its peers to replicate. Consumers have typically purchased fewer new cars during recessions, instead opting to spend more money to repair older cars. During the past two major market corrections, O’Reilly’s often recession-resistant business model has translated into good relative performance for the company’s shares. However, the stock slightly underperformed the Russell Index (-2%) during this most recent market slump, as the number of miles driven in the U.S. has plummeted due to COVID-19 stay-at-home orders, and consumers have been avoiding any unnecessary contact with stores and repair shops. We believe that once non-essential businesses reopen, miles driven will increase, and so could the need for auto repairs.
Another example of a “defensive” stock that underperformed during this market correction is Ross Stores, an off-price apparel retailer that was also one of the top 10 detractors from the Fund’s benchmark-relative performance during the first quarter of 2020. The stock outperformed the market during the 2008/2009 recession, despite the fact that customers spent less on apparel overall, because a greater percentage of the spending went toward purchases of off-price merchandise. Similar to the situation with
6 Pioneer Fundamental Growth Fund | Annual Report | 3/31/20

O’Reilly, in the current COVID-19 environment, consumers have been avoiding shopping at stores, and Ross has temporarily closed the vast majority of its physical locations. That dynamic has put near-term pressure on the stock, but it has not altered our long-term investment case that Ross could be a prime beneficiary of the shift away from full-price apparel department stores to off-price stores. We believe that shift is likely to accelerate once people go back to work, as they may be more budget-conscious than they were prior to the COVID-19 crisis. Moreover, we believe Ross could have an opportunity to purchase excess apparel inventory from manufacturers and full-price retailers at greatly discounted prices.
Other portfolio holdings that notably lagged and detracted from the Fund’s benchmark-relative returns throughout the 12-month period included defense contractor Raytheon. One factor driving the stock’s underperformance was investors’ concerns about the company’s pending merger with United Technologies (not a Fund holding), a major producer of aircraft engines and other aerospace products. We had based our investment case for Raytheon on its historically strong returns on capital, competitive advantages in military tech