As filed with the Securities and Exchange Commission on July 14, 2023.March 20, 2024.

Registration No. 333- 273067

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

Amendment No. 1 to

FORM S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

APTEVO THERAPEUTICS INC.

(Exact Name of Registrant as Specified in Its Charter)

2401 4th Avenue, Suite 1050

Seattle, Washington, 98121

(206) 838-0500

(Address, Including Zip Code, and Telephone Number, Including Area Code, of Registrant’s Principal Executive Offices)

Marvin L. White

President and Chief Executive Officer

Aptevo Therapeutics Inc.

2401 4th Avenue, Suite 1050

Seattle, Washington, 98121

(206) 838-0500

(Name, Address, Including Zip Code, and Telephone Number, Including Area Code, of Agent For Service)

Copies to:

Approximate date of commencement of proposed sale to the public: As soon as practicable after the effective date of this registration statement.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box. ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant files a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information in this prospectus is not complete and may be changed. These securities may not be sold until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

SUBJECT TO COMPLETION DATED JULY 14, 2023March 20, 2024

PRELIMINARY PROSPECTUS

Up to 7,692,308 Shares of Common Stock or Common Stock Underlying Pre-Funded Warrants

Common Warrants to purchase up to 7,692,308 Shares of Common Stock

Pre-Funded Warrants to purchase up to 7,692,308922,509 Shares of Common Stock

Up to 7,692,308922,509 Pre-Funded Warrants to Purchase up to 922,509 Shares of Common Stock Underlying

Up to 1,845,018 Common Warrants to Purchase up to 1,845,018 Shares of Common Stock

Up to 2,767,527 Shares of Common Stock underlying the Pre-Funded Warrants and Common Warrants

This is a reasonable best efforts public offering of up to 7,692,308922,059 shares (the “Shares”“shares”) of our common stock, par value $0.001 per share ("Common Stock"common stock") includingtogether with up to 1,845,018 common warrants to purchase up to 1,845,018 shares of Common Stock underlying common warrants, and common stock purchase warrants (the “Common Warrants”) to purchase an aggregate of up to 7,692,308 shares of our Common Stock at an assumed combined public offering price of $1.56$5.42 per share and common warrant (the last reported sale price per share of Common Stock and Common Warrant (assuming a public offering price equal to the last sale price of our Common Stock as reported bycommon stock on the Nasdaq Capital Market, (“Nasdaq”) on July 13, 2023 of $1.56)March 15, 2024). Each Common Warrantshare of common stock is assumedbeing offered together with two common warrants, each to purchase one share of common stock. The common warrants will have an exercise price of $1.56$ per Share (100% of the public offering price per Share and Common Warrant),share, will be exercisable upon issuance and will expire five years from the date of issuance. The shares of common stock and common warrants will be separately issued. This prospectus also covers the shares of common stock issuable from time to time upon the exercise of the common warrants.

We are also offering pre-funded warrants to those purchasers, if any, whose purchase of Common Stockshares of common stock in this offering would otherwise result in any suchthe purchaser, together with its affiliates and certain related parties, beneficially owning more than 4.99% (or, at the election of suchthe purchaser, 9.99%) of our outstanding Common Stock immediatelycommon stock following the consummation of this offering the opportunity to purchase pre-funded warrants (the “Pre-Funded Warrants”) in lieu of the shares of our Common Stockcommon stock that would otherwise result in such purchaser’s beneficial ownership exceedingin excess of 4.99% (or, at the election of suchthe purchaser, 9.99%). Each pre-funded warrant will be exercisable for one share of our outstanding Common Stock.common stock at an exercise price of $0.0001 per share. Each pre-funded warrant is being offered together with the same two common warrants, each to purchase one share of common stock described above being offered with each share of common stock. The purchase price forof each Pre-Funded Warrantpre-funded warrant will equal the per sharecombined public offering price for the Common Stockper share of common stock and common warrants being sold in this offering, less the $0.001$0.0001 per share exercise price of each such Pre-Funded Warrant.pre-funded warrant. Each Pre-Funded Warrantpre-funded warrant will be exercisable upon issuance and will not expire prior to exercise.when exercised in full. The pre-funded warrants and common warrants will be separately issued. For each Pre-Funded Warrantpre-funded warrant that we sell, the number of shares of Common Stockcommon stock that we are offeringselling will be decreased on a one-for-one basis.

For purposes of clarity, each share of Common Stock or Pre-Funded Warrant to purchase one share of Common Stock is being sold together with a Common Warrant to purchase one share of Common Stock.

These securities are being sold in this offering to certain purchasers under a securities purchase agreement dated , 2023 between us and such purchasers. Pursuant to this This prospectus we are also offeringcovers the shares of Common Stockcommon stock issuable from time to time upon the exercise of Pre-Funded Warrantsthe pre-funded warrants.

There is no established public trading market for the pre-funded warrants or common warrants, and Common Warrants offered hereby.

The shares issuable upon exercisewe do not expect a market to develop. We do not intend to apply for listing of the Pre-Funded Warrantspre-funded warrants or Common Warrantscommon warrants on any securities exchange or other nationally recognized trading system. Without an active trading market, the liquidity of the pre-funded warrants and common warrants will be issued uponlimited.

We have engaged Roth Capital Partners, LLC, or the exercise thereof. Because thereplacement agent, to act as our exclusive placement agent in connection with this offering. The placement agent has agreed to use its reasonable best efforts to arrange for the sale of the securities offered by this prospectus. The placement agent is not purchasing or selling any of the

securities we are offering and the placement agent is not required to arrange the purchase or sale of any specific number or dollar amount of securities. We have agreed to pay to the placement agent the placement agent fees set forth in the table below, which assumes that we sell all of the securities offered by this prospectus. There is no arrangement for funds to be received in escrow, trust or similar arrangement. There is no minimum number of shares of securities or minimum aggregate amount of proceeds that is a condition for this offering to close, weclose. We may sell fewer than all of the securities offered hereby, which may significantly reduce the amount of proceeds received by us, and investors in this offering will not receive a refund in the event thatif we do not sell an amountall of the securities sufficient to pursue the business goals outlined in this prospectus.offered hereby. Because there is no escrow account and there is no minimum offeringnumber of securities or amount of proceeds, investors could be

in a position where they have invested in our company,us, but we are unable to fulfill our objectives due to a lack of interesthave not raised sufficient proceeds in this offering. Also, any proceeds fromoffering to adequately fund the sale of securities offered by us will be available for our immediate use, despite uncertainty about whether we would be able to use such funds to effectively implement our business plan.

The offeringintended uses of the Shares, Pre-Funded Warrants and Common Warrantsproceeds as described in this prospectus. We will terminatebear all costs associated with the offering. See “Plan of Distribution” on page 23 of this prospectus for more information regarding these arrangements. This offering will end no later than August 31, 2023; however,three trading days from the sharesdate of our Common Stock underlying the Pre-Funded Warrants and the Common Warrants will be offered on a continuous basis pursuant to Rule 415 under the Securities Act of 1933, as amended (the “Securities Act”).this prospectus.

Our Common Stock tradescommon stock is listed on the Nasdaq Capital Market under the symbol “APVO.” On, July 13, 2023,March 15, 2024, the last reported sale price of our Common Stockcommon stock on the Nasdaq Capital Market was $1.56$5.42 per share. TheAll share, common warrant and pre-funded warrant numbers are based on an assumed combined public offering pricesprice of $5.42 per Shareshare or pre-funded warrant, as applicable, and accompanying Common Warrant orcommon warrants. The actual combined public offering price per Pre-Funded Warrantshare and accompanying Common Warrantcommon warrants and the actual combined public offering price per pre-funded warrant and common warrants will be determined between us and investors based on market conditions at the time of pricing, and may be at a discount to the current market price of our Common Stock.common stock. Therefore, the recent market price and resulting assumed public offering price used throughout this prospectus may differ substantially from the actual offering price. Nonenot be indicative of the Common Warrants or Pre-Funded Warrants are listedfinal public offering price.

You should read this prospectus, together with additional information described under the headings “Incorporation of Certain Information By Reference” and “Where You Can Find More Information,” carefully before you invest in any of our securities.

Investing in our securities involves a high degree of risk. See the section entitled “Risk Factors” beginning on a national securities exchange. We do not intend to apply to list the Common Warrants or Pre-Funded Warrants on any national securities exchange. Without an active trading market, the liquidity of the Common Warrants and Pre-Funded Warrants may be limited.

We expect this offering to be completed within two business days following the commencementpage 7 of this offeringprospectus and we will deliver all securities toin the documents incorporated by reference into this prospectus for a discussion of risks that should be issuedconsidered in connection with this offering delivery versus payment upon receipt of investor funds received by us.

INVESTING IN OUR SECURITIES INVOLVES A HIGH DEGREE OF RISK. YOU SHOULD CAREFULLY READ AND CONSIDER THE RISKS AND UNCERTAINTIES DESCRIBED UNDER THE HEADING “RISK FACTORS” BEGINNING ON PAGE 12 OF THIS PROSPECTUS AND UNDER SIMILAR HEADINGS IN ANY AMENDMENTS OR SUPPLEMENTS TO THIS PROSPECTUS, INCLUDING OUR MOST RECENT ANNUAL REPORT ON FORM 10-K AND ANY SIMILAR SECTION CONTAINED IN ANY DOCUMENTS THAT ARE INCORPORATED BY REFERENCE INTO THIS PROSPECTUS.

Neither the Securities and Exchange Commission (THE "SEC") nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

We have engaged A.G.P./Alliance Global Partners asan investment in our exclusive placement agent (“A.G.P.” or the “Placement Agent”) to use its reasonable best efforts to solicit offers to purchase our securities in this offering. The Placement Agent has no obligation to purchase any of the securities from us or to arrange for the purchase or sale of any specific number or dollar amount of the securities. Because there is no minimum offering amount required as a condition to closing in this offering the actual public offering amount, placement agent’s fee, and proceeds to us, if any, are not presently determinable and may be substantially less than the total maximum offering amounts set forth above and throughout this prospectus. We have agreed to pay the Placement Agent the placement agent fees set forth in the table below and to provide certain other compensation to the Placement Agent. See “Plan of Distribution” beginning on page of this prospectus for more information regarding these arrangements.

_________________________________________________

(2) The above summary of offering proceeds does not give effect to any proceeds from the exercisedelivery of the Common Warrants or Pre-Funded Warrant being issued in this offering.

Deliveryshares of the Sharescommon stock and Pre-Funded Warrants, together with accompanying Common Warrants,any pre-funded warrants and common warrants to purchasers is expected to be made on or about , 2023, subject to customary closing conditions.no later than April 20, 2024.

Sole Placement AgentNeither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

A.G.P.

Roth Capital Partners

The date of this prospectus is , 2023.2024.

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement on Form S-1 that we filed with the SEC to register the securities offered hereby under the Securities Act. We may also file a prospectus supplement or post-effective amendment to the registration statement of which this prospectus forms a part that may contain material information relating to these offerings. The prospectus supplement or post-effective amendment may also add, update or change information contained in this prospectus with respect to that offering. If there is any inconsistency between the information in this prospectus and the applicable prospectus supplement or post-effective amendment, you should rely on the prospectus supplement or post-effective amendment, as applicable. Before purchasing any securities, you should carefully read this prospectus, any post-effective amendment, and any applicable prospectus supplement, together with the additional information incorporatedincorporate by reference important information into this prospectus and described under the heading “Where You Can Find More Information.”prospectus. You may obtain the information incorporated by reference without charge by following the instructions under “Where“Where You Can Find More Information.” You should carefully read this prospectus as well as additional information described under “Information Incorporated“Incorporation of Certain Information by Reference,” before deciding to invest in our securities.

You should rely only on the information contained in this prospectus.

We have not, and the Placement Agentplacement agent has not, authorized anyone to provide you with any information or to make any representations other than thatthose contained in this prospectus.prospectus or in any free writing prospectuses prepared by or on behalf of us or to which we have referred you. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. This prospectus mayis an offer to sell only be usedthe securities offered hereby, and only under circumstances and in jurisdictions where it is legallawful to offer and sell our securities.do so. The information contained in this prospectus or in any applicable free writing prospectus is accuratecurrent only as of theits date, of this prospectus, regardless of theits time of delivery of this prospectus or any sale of our securities. Our business, financial condition, results of operations and prospects may have changed since that date. We are not,

The information incorporated by reference or provided in this prospectus contains statistical data and estimates, including those relating to market size and competitive position of the markets in which we participate, that we obtained from our own internal estimates and research, as well as from industry and general publications and research, surveys and studies conducted by third parties. Industry publications, studies and surveys generally state that they have been obtained from sources believed to be reliable. While we believe our internal company research is reliable and the Placement Agent is not, making an offerdefinitions of our market and industry are appropriate, neither this research nor these securities indefinitions have been verified by any jurisdiction where the offer is not permitted.independent source.

For investors outside the United States: We have not, and the Placement Agentplacement agent has not, done anything that would permit this offering or possession or distribution of this prospectus in any jurisdiction where action for that purpose is required, other than in the United States. Persons outside the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, the offering of the securities and the distribution of this prospectus outside the United States.

For purposes of this prospectus, references to the terms “APVO,” “the Company,” “we,” “us” and “our” refer to Aptevo Therapeutics Inc., together with its subsidiaries, unless the context otherwise requires.

This prospectus and the information incorporated herein by reference includeinto this prospectus contain references to our trademarks service marksand to trademarks belonging to other entities. Solely for convenience, trademarks and trade names owned by us or other companies. All trademarks, service marksreferred to in this prospectus and trade names included orthe information incorporated by reference into this prospectus, including logos, artwork, and other visual displays, may appear without the information incorporated herein by reference® or TM symbols, but such references are the property of their respective owners.

We urge younot intended to read carefully this prospectus, as supplemented and amended, before deciding whether to investindicate, in any way, that we will not assert, to the fullest extent under applicable law, our rights or the rights of the securities being offered.applicable licensor to these trademarks and trade names. We do not intend our use or display of other companies’ trade names or trademarks to imply a relationship with, or endorsement or sponsorship of us by, any other company.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING INFORMATIONSTATEMENTS

This prospectus, the applicable prospectus supplement and any free writing prospectus, including the documents we incorporate by reference, herein and therein, contain certain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 andthat involve substantial risks and uncertainties. All statements contained in this prospectus and any documents we incorporate by reference, other than statements of historical factfacts, are forward-looking statements. These statements include, but are not limited to,including statements regarding our intentions, beliefs, projections, outlook, analyses or current expectations concerning, among other things, our ongoing and planned preclinical development and clinical trials, the timing of and our ability to make regulatory filings and obtain and maintain regulatory approvals for our product candidates and anystrategy, future product candidates, our intellectual property position, the degree of clinical utility of our product candidates, particularly in specific patient populations, our ability to develop and commercialize any product candidates, expectations regarding clinical trial data, statements regarding potential milestone payments, potential partnerships and collaborations, the advancement of our clinical and pre-clinical trials, our goals and milestones, our expectations regarding the size of the patient populations for our product candidates if approved for commercial use, our expectations regarding the effectiveness of our ADAPTIR and ADAPTIR-FLEX platforms, our ability to utilize any net operating losses, our results of operations, cash needs, spending of the proceeds from the offering described in this prospectus, financial condition, liquidity, prospects, growth and strategies, the industry in which we operate and the trends that may affect the industry or us. In some cases, you can identify forward-looking statements by terminology such as “believe,” “will,” “may,” “estimate,” “continue,” “anticipate,” “intend,” “should,” “plan,” “might,” “approximately,” “expect,” “predict,” “could,” “potentially” or the negative of these terms or other similar expressions, but the absence of these words does not mean that a statement is not forward looking.

These statements relate to future events or our future financial performanceposition, future revenue, projected costs, prospects, plans, objectives of management and expected market growth. These statements involve known and unknown risks, uncertainties and other important factors that couldmay cause our actual results, levels of activity, performance or achievements to be materially different from any future results, of operations to differ materially from thoseperformance or achievements expressed or implied by thesethe forward-looking statements. These statements reflect our views with respect

The words “anticipate”, “believe”, “estimate”, “expect”, “intend”, “may”, “plan”, “predict”, “project”, “target”, “potential”, “will”, “would”, “could”, “should”, “continue” and similar expressions are intended to future events as of the time they were made and are based on assumptions and subject to risks and uncertainties. You should read the matters described in “Risk Factors” in this prospectus, in our Annual Report on Form 10-K and in our Quarterly Report on Form 10-Q which is incorporated by reference into this prospectus and the other cautionary statements made in this prospectus as being applicable to all relatedidentify forward-looking statements, wherever they appear in this prospectus or the documents incorporated by reference into this prospectus. In addition to factors identified under the section titled “Risk Factors” in this prospectus, factors that may impact suchalthough not all forward-looking statements include:contain these identifying words. These forward-looking statements include, among other things, statements about:

ii

These forward-looking statements are only predictions and we may not currently known to us ariseactually achieve the plans, intentions or shouldexpectations disclosed in our underlying assumptions prove incorrect, actual results and plans could differ materially from those expressed in any forward-looking statements. Given these uncertainties,statements, so you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make. We have based these forward-looking statements. Except as required by law,statements largely on our current expectations and projections about future events and trends that we undertake nobelieve may affect our business, financial condition and operating results. We have included important factors in the cautionary statements included in this prospectus that could cause actual future results or events to differ materially from the forward-looking statements that we make. Our forward-looking statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, joint ventures or investments we may make.

You should read this prospectus with the understanding that our actual future results may be materially different from what we expect. We do not assume any obligation to update or revise publicly any forward-looking statements whether as a result of new information, future events or otherwise.otherwise, except as required by applicable law.

RISK FACTORS

An investment in our securities involves a significanthigh degree of risk. YouBefore deciding whether to purchase our securities, including the shares of common stock offered by this prospectus, you should carefully consider the risk factorsrisks and all of the other information included in this prospectus and the documents we have incorporated by reference into this prospectus, including those in “Item 1A. Riskuncertainties described under “Risk Factors” in our Annual Report on Form 10-K for the fiscal year ended December 31, 2023, and ourany subsequent Quarterly Report on Form 10-Q forand our other filings with the period ended March 31, 2023,SEC, all of which are incorporated herein by reference before making an investment decision. Anyherein. If any of these risks and uncertainties could have a material adverse effect onactually occur, our business, financial condition cash flows and results of operations could be materially and adversely affected and we may not be able to achieve our goals, the value of our securities could decline and you could lose some or all of your investment. Additional risks not presently known to us or that we currently believe are immaterial may also significantly impair our business operations. If any of these risks occur, our business, results of operations or financial condition and prospects could be harmed. In that occurs,event, the tradingmarket price of our Common Stockcommon stock and the value of the warrants could decline, materially, and you could lose all or part of your investment.

The risks included in this prospectus and the documents we have incorporated by reference into this prospectus are not the only risks we face. We may experience additional risks and uncertainties not currently known to us, or as a result of developments occurring in the future. Conditions that we currently deem to be immaterial may also materially and adversely affect our business, financial condition, cash flows and results of operations, and our ability to pay distributions to stockholders.

Risks Related to This Offering

We have broad discretion in the use of the net proceeds from this offering and may not use them effectively.

Our management will have broad discretion in the application of the net proceeds, including for any of the purposes described in the section of this prospectus entitled “Use of Proceeds.” You will be relying on the judgment of our management with regard to the use of these net proceeds, and you will not have the opportunity, as part of your investment decision, to assess whether the net proceeds are being used appropriately. The failure by our management to apply these funds effectively could result in financial losses that could have a material adverse effect on our business, cause the price of our securities to decline and delay the development of our product candidates. Pending the application of these funds, we may invest the net proceeds from this offering in a manner that does not produce income or that loses value.

You will experience immediate and substantial dilution in the net tangible book value per share of the Common Stockcommon stock you purchase. You may also experience future dilution as a result of future equity offerings.

The price per share, together with the number of shares of our Common Stockcommon stock we propose to issue and ultimately will issue if this offering is completed, may result in an immediate decrease in the market price of our Common Stock.common stock. Our historical net tangible book value as of MarchDecember 31, 2023 was $20.1$10.1 million, or approximately $2.78$22.73 per share of our Common Stock.common stock. After giving effect to the 7,692,308922,509 shares of our Common Stockcommon stock or the exercise of the Pre-Funded Warrantspre-funded warrants to be sold in this offering at a public offering price of $1.56$5.42 per share, (assuming a public offering price equal to the last sale price of our Common Stock as reported by Nasdaq on July 13, 2023, which was $1.56 per share), our as adjusted net tangible book value as of MarchDecember 31, 2023 would have been $31.2,$14.6 million, or approximately $2.09$10.70 per share of our Common Stock.common stock. This represents an immediate dilution in the net tangible book value of $0.69$12.03 per share of our Common Stockcommon stock to our existing stockholders and an immediate increase in net tangible book value of approximately $0.53$5.28 per share of our Common Stockcommon stock to new investors, representing the difference between the assumed public offering price and our as adjusted net tangible book value as of MarchDecember 31, 2023, after giving effect to this offering, and the assumed public offering price per share.

In addition, in order to raise additional capital, we may in the future offer additional shares of our Common Stockcommon stock or other securities convertible into or exchangeable for our Common Stockcommon stock at prices that may not be the same as the price per share in this offering. In the event that the outstanding options or warrants are exercised or settled, or that we make additional issuances of Common Stockcommon stock or other convertible or exchangeable securities, you could experience additional dilution. We cannot assure you that we will be able to sell shares or other securities in any other offering at a price per share that is equal to or greater than the price per share paid by investors in this offering, and investors purchasing shares or other securities in the future could have rights superior to existing stockholders, including investors who purchase shares of Common Stockcommon stock in this offering. The price per share at which we sell additional shares of our Common Stockcommon stock or securities convertible into Common Stockcommon stock in future transactions, may be higher or lower than the price per share in this offering. As a result, purchasers of the shares we sell, as well as our existing stockholders, will experience significant dilution if we sell at prices significantly below the price at which they invested.

Resales of our Common Stock in the public market during this offering by our stockholders may cause the market price of our Common Stock to fall.

Sales of a substantial number of shares of our Common Stock could occur at any time. The issuance of new shares of our Common Stock could result in resales of our Common Stock by our current stockholders concerned about the potential ownership dilution of their holdings. In turn, these resales could have the effect of depressing the market price for our Common Stock.

You may experience future dilution as a result of future equity offerings.

There is no public market for the Pre-Funded Warrants and Common Warrantscommon warrants or pre-funded warrants being offered by us in this offering.

There is no established public trading market for the Pre-Funded Warrants and Common Warrants being offered in this offering,common warrants or the pre-funded warrants, and we do not expect a market to develop. In addition, we do not intend to apply to list the Pre-Funded Warrants and Common Warrantscommon warrants or pre-funded warrants on any national securities exchange or other nationally recognized trading system. Without an active market, the liquidity of the Pre-Funded Warrantscommon warrants and Common Warrantspre-funded warrants will be limited.

Holders of our Pre-Funded Warrants and Common Warrants will have no rights as common stockholders until they acquire our Common Stock.

Until you acquire shares of Common Stock upon exercise of your Pre-Funded Warrants or the Common Warrants, you will have no rights with respect to the shares of Common Stock issuable upon exercise of your Common Warrants. Upon exercise of your Pre-Funded Warrants or the Common Warrants, you will be entitled to exercise the rights of a holder of shares only as to matters for which the record date occurs after the issuance date for such shares of Common Stock.

The Pre-Funded Warrantscommon warrants and the Common Warrantspre-funded warrants are speculative in nature.

The Pre-Funded Warrantscommon warrants and Common Warrantspre-funded warrants offered hereby do not confer any rights of Common Stockshare of common stock ownership on their holders, such as voting rights or the right to receive dividends, but rather merely represent the right to acquire shares of Common Stockcommon stock at a fixed price. Specifically, commencing on the date of issuance, holders of the Pre-Funded Warrantscommon warrants may acquire the Common Stockshares of common stock issuable upon exercise of such warrants at an exercise price of $0.001$5.42 per share of common stock, and holders of the Common Warrantspre-funded warrants may acquire the Common Stockshares of common stock issuable upon exercise of such warrants at an exercise price of $0.0001 per share equal to the public offering price of shares of Common Stock in this offering.common stock. Moreover, following this offering, the market value of the Pre-Funded Warrantscommon warrants and the Common Warrants

pre-funded warrants is uncertain and there can be no assurance that the market value of the Pre-Funded Warrantscommon warrants or the Common Warrantspre-funded warrants will equal or exceed their respective public offering price.

The Common Warrants may not have any value.

Each Common Warrant has an exercise price per share equal toprices. There can be no assurance that the public offeringmarket price of the Shares in this offering and expires on the fifth anniversaryshares of its original issuance date. In the event the market price per share of Common Stock does notcommon stock will ever equal or exceed the exercise price of the Common Warrants duringcommon warrants or pre-funded warrants, and consequently, whether it will ever be profitable for holders of common warrants to exercise the period whencommon warrants or for holders of the Common Warrants are exercisable,pre-funded warrants to exercise the Common Warrants may notpre-funded warrants.

Holders of the warrants offered hereby will have any value.no rights as common stockholders with respect to the shares of our common stock underlying the warrants until such holders exercise their warrants and acquire our common stock, except as otherwise provided in the warrants.

Until holders of the common warrants and the pre-funded warrants acquire shares of our common stock upon exercise thereof, such holders will have no rights with respect to the shares of our common stock underlying such warrants, except to the extent that holders of such warrants will have certain rights to participate in distributions or dividends paid on our common stock as set forth in the warrants. Upon exercise of the common warrants and the pre-funded warrants, the holders will be entitled to exercise the rights of a common stockholder only as to matters for which the record date occurs after the exercise date.

This is a reasonable best efforts offering, in which no minimum number or dollar amount of securities is required to be sold, and we may not raise the amount of capital we believe is required for our business plans, including our near-term business plans.

The Placement Agentplacement agent has agreed to use its reasonable best efforts to solicit offers to purchase the securities in this offering. The Placement Agentplacement agent has no obligation to buy any of the securities from us or to arrange for the purchase or sale of any specific number or dollar amount of the securities. There is no required minimum number of securities that must be sold as a condition to completion of this offering. Because there is no minimum offering amount required as a condition to the closing of this offering, the actual offering amount, placement agent fees and proceeds to us are not presently determinable and may be substantially less than the maximum amounts set forth herein.above. We may sell fewer than all of the securities offered hereby, which may significantly reduce the amount of proceeds received by us, and investors in this offering will not receive a refund.refund in the event that we do not sell an amount of securities sufficient to support our continued operations, including our near-term continued operations. Thus, we may not raise the amount of capital we believe is required for our operations in the short-term and may need to raise additional funds, to complete such short-term operations. Such additional fundraiseswhich may not be available or available on terms acceptable to us.

Purchasers who purchase our securities in this offering pursuant to a securities purchase agreement may have rights not available to purchasers that purchase without the benefit of a securities purchase agreement.

In addition to rights and remedies available to all purchasers in this offering under federal securities and state law, the purchasers that enter into a securities purchase agreement will also be able to bring claims of breach of contract against us. The Placement Agent isability to pursue a claim for breach of contract provides those investors with the means to enforce the covenants uniquely available to them under the securities purchase agreement including, but not limited

to: (i) timely delivery of securities; (ii) agreement to not enter into any financings for 60 days from closing; and (iii) indemnification for breach of contract.

Resales of our common stock in the public market during this offering by our stockholders may cause the shares onmarket price of our common stock to fall.

Sales of a “reasonable best efforts” basis and the Placement Agent is under no obligation to purchase any shares for its own account. The Placement Agent is not required to sell any specificsubstantial number or dollar amount of shares of Common Stockour common stock could occur at any time. The issuance of new shares of our common stock could result in resales of our common stock by our current stockholders concerned about the potential ownership dilution of their holdings. In turn, these resales could have the effect of depressing the market price for our common stock.

This offering may cause the trading price of our common stock to decrease.

The price per share, together with the number of shares of common stock we propose to issue and ultimately will issue if this offering but will use its reasonable best efforts to sellis completed, may result in an immediate decrease in the securities offered inmarket price of our common stock. This decrease may continue after the completion of this prospectus. As a “reasonable best efforts” offering, there can be no assurance that the offering contemplated hereby will ultimately be consummated.offering.

USE OF PROCEEDS

We estimate that we will receivethe net proceeds of approximately $12.0 million from the sale of the securities by us in this offering based on an assumed combined public offering price of $1.56 per share and accompanying Common Warrant (assuming a public offering price equal to the last sale price of our Common Stock as reported by Nasdaq on July 13, 2023, which was $1.56),will be approximately $4.6 million, after deducting the Placement Agentplacement agent fees and estimated offering expenses payable by us, assuming no sale of any fixed combinations of pre-funded warrants and excludingwarrants offered hereunder. If the common warrants are exercised in full for cash, the estimated net proceeds if any, received fromwill increase to $9.2 million. However, because this is a reasonable best-efforts offering and there is no minimum offering amount required as a condition to the exerciseclosing of warrants issued in this offering.offering, the actual offering amount, the placement agent’s fees and net proceeds to us are not presently determinable and may be substantially less than the maximum amounts set forth on the cover page of this prospectus.

We currently intend to use the net proceeds we receive from this offering for working capital to fund our clinical programs and general corporate purposes, including the continued clinicalfurther development of our product candidates and for working capital, and other general corporate purposes. Ourcandidates. This expected use of net proceeds from this offering represents our intentions based onupon our presentcurrent plans and prevailing business conditions, which could change in the future as our plans and prevailing business conditions evolve. The amountamounts and timing of our actual expendituresuse of proceeds will dependvary depending on numerousa number of factors, including the timing and successamount of clinical studiescash generated or clinical studies we may commence in the future, the timing of regulatory submissions and the feedback from regulatory authorities.used by our operations. As a result, our managementwe will haveretain broad discretion overin the useallocation of the net proceeds fromof this offering. Pending our use of the net proceeds from this offering, we may temporarily invest the net proceeds in investment-grade, interest-bearing securities.

Predicting the cost necessary to develop product candidates can be difficult and we anticipate we will need additional funds to complete the development work generally required for obtaining regulatory approval to commercialize a drug. We have based these estimates on assumptions that may prove to be wrong, and we could use our available capital resources sooner than we currently expect.

We estimate that the total expenses of the offering, including registration, filing and listing fees, printing fees and legal and accounting expenses, but excluding placement agent fees, will be approximately $186,000, all of which are payable by us. This figure includes the placement agent’s accountable expenses, including, but not limited to, legal fees for placement agent’s legal counsel, that we have agreed to pay at the closing of the offering up to an aggregate expense reimbursement of $100,000.

Tail

In the event this offering does not close we have also agreed to pay the Placement Agent a tail fee equal to the cash compensation in this offering, subject to certain exceptions, if any investor, who the Placement Agent conducted discussions with on behalf of the Company during the 90 days following its engagement, or if any of the separately agreed upon investors, provides us with capital in any offering of the Company’s securities during the six month period following expiration or termination of our engagement of the Placement Agent.

Other Relationships

The placement agent may, from time to time, engage in transactions with or perform services for us in the ordinary course of its business and may continue to receive compensation from us for thissuch services.

Determination of Offering Price

The combined public offering excludingprice per share and common warrants and the combined public offering price per pre-funded warrant and common warrants we are offering and the exercise prices and other terms of the warrants were negotiated between us and the investors, in consultation with the placement agent feesbased on the trading of our common stock prior to this offering, among other things. Other factors considered in determining the public offering prices of the securities we are offering and expenses,the exercise prices and other terms of the warrants include the history and prospects of our company, the stage of development of our business, our business plans for the future and the extent to which they have been implemented, an assessment of our management, general conditions of the securities markets at the time of the offering and such other factors as were deemed relevant.

Lock-Up Agreements

Each of our officers and directors have agreed to be subject to a lock-up period of 90 days following the date of this prospectus. This means that, during the applicable lock-up period, they may not offer for sale, contract to sell, or sell any shares of our common stock or any securities convertible into, or exercisable or exchangeable for, shares of our common stock subject to certain customary exceptions. In addition, we have agreed to not issue any shares of common stock or securities exercisable or convertible into shares of common stock for a period of 60 days following the closing date of this offering, subject to certain exceptions, or enter into an agreement to issue securities at a future determined price, for a period of 90 days following the closing date of this offering.

Transfer Agent and Registrar

Broadridge Financial Solutions, Inc. is the transfer agent and registrar for our common stock, which can be contacted at 51 Mercedes Way, Edgewood, NY 11717, shareholder@broadridge.com, or +1 (720) 378-5591.

The Nasdaq Capital Market Listing

Our common stock is currently listed on the Nasdaq Stock Market LLC under the symbol “APVO.” On March 15, 2024, the reported closing price per share of our common stock was $5.42. The final public offering price will be approximately $ .determined between us, the placement agent and the investors in the offering, and may be at a discount to the current market price of our common stock. Therefore, the assumed public offering price used throughout this prospectus may not be indicative of the final public offering price. There is no established public trading market for the common warrants or pre-funded warrants, and we do not expect such markets to develop. In addition, we do not intend to apply for a listing of the common warrants or pre-funded warrants on any national securities exchange or other nationally recognized trading system.

Indemnification

We have agreed to indemnify the placement agent against certain liabilities, including certain liabilities arising under the Securities Act, or to contribute to payments that the placement agent may be required to make for these liabilities.

Regulation M

The Placement Agentplacement agent may be deemed to be an underwriter within the meaning of Section 2(a)(ii)(11) of the Securities Act.Act and any commissionsfees received by it and any profit realized on the resalesale of the securities sold by it while acting as principal might be deemed to be underwriting discounts or commissions under the Securities Act. As an underwriter, the Placement Agent wouldThe placement agent will be required to comply with the requirements of the Securities Act and the Exchange Act of 1934, as amended (the “Exchange Act”), including, without limitation, Rule 4l5(a)(4) under the Securities Act and Rule 10b-5 and Regulation M under the

Exchange Act. These rules and regulations may limit the timing of purchases and sales of our securities by the Placement Agent acting as principal.placement agent. Under these rules and regulations, the Placement Agent:

Lock-Up Agreements

Electronic Distribution

Our directors and executive officers have agreed to enter lock-up agreements. Under these agreements, these individuals have agreed, subject to specified exceptions, not to sell or transfer any shares of Common Stock or securities convertible into, or exchangeable or exercisable for, our shares of Common Stock during a period ending 90 days after the date of this

A prospectus without first obtaining the written consent of the Placement Agent, subject to certain exceptions. Specifically, these individuals have agreed, in part, not to:

Notwithstanding these limitations, our securitieselectronic format may be transferred under limited circumstances, including, without limitation,made available on a website maintained by gift, will or intestate succession.

In addition, we have agreed that, subject to certain exceptions, (i) we will not conduct any issuances of our Common Stock for a period of 90 days following closing of this offering and that (ii) we will not enter into a variable rate transaction for a period of 180 days following the closing of this offering.

Determination of Offering Price

The public offering price of the securities we are offering was negotiated between usplacement agent and the investors,placement agent may distribute prospectuses electronically. Other than the prospectus in consultation withelectronic format, the Placement Agent basedinformation on the trading of our shares of Common Stock prior to the offering, among other things. Other factors considered in determining the public offering price of the securities we are offering include our history and prospects, the industry in which we operate, our past and present operating results, the stage of development of our business, our business plans for the future and the extent to which they have been implemented, the previous experience of our executive officers, general conditions of the securities markets at the time of the offering and such other factors as were deemed relevant.

Listing

Our Common Stock is listed on the Nasdaq under the symbol “APVO.” There is no established public trading market for the warrants or Pre-Funded Warrants, and we do not expect such a market to develop. We do not intend to apply to list the warrants or Pre-Funded Warrants on any securities exchange or other nationally recognized trading system. Without an active trading market, the liquidity of the warrants will be limited.

Discretionary Accounts

The Placement Agent does not intend to confirm sales of the securities offered hereby to any accounts over which it has discretionary authority.

Other Activities and Relationships

The Placement Agent and certain of its affiliates are full service financial institutions engaged in various activities, which may include securities trading, commercial and investment banking, financial advisory, investment management, investment research, principal investment, hedging, financing and brokerage activities. The Placement Agent and certain of its affiliates have, from time to time, performed, and may in the future perform, various commercial and investment banking and financial advisory services for us and our affiliates, for which they received or will receive customary fees and expenses.

In addition, in the ordinary course of their various business activities, the Placement Agent and certain of its affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the· accounts of their customers, and such investment and securities activities may involve securities and/or instruments issued by us and our affiliates. If the Placement Agent or its affiliates enter into a lending relationship with us, they will routinely hedge their credit exposure to us consistent with their customary risk management policies. The Placement Agent and its affiliates may hedge such exposure by entering into transactions that consist of either the purchase of credit default swaps or the creation of short positions in our securities or the securities of our affiliates, including potentially the Common Stock offered hereby. Any such short positions could adversely affect future trading prices of the Common Stock offered hereby. The Placement Agent and certain of its affiliates may also communicate independent investment recommendations, market color or trading ideas and/or publish or express independent research views in respect of such securities or instruments and may at any time hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

LEGAL MATTERS

The validity of the securities being offered by this prospectus will be passed upon by Paul Hastings LLP, Washington, DC. The Placement Agent is being represented in connection with this offering by Sullivan & Worcester LLP, New York, New York. Additional legal matters may be passed upon for us or any underwriters, dealers or agents, by counsel that we will name in an applicable prospectus supplement.

EXPERTS

Our consolidated financial statements as of December 31, 2022 and 2021, and for the years then ended, incorporated in this prospectus by reference and included in our Annual Report on Form 10-K for the year ended December 31, 2022, have been audited by Moss Adams LLP, an independent registered public accounting firm, as set forth in their report therein. Such consolidated financial statements are incorporated by reference in reliance upon the report of such firm given their authority as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

We have filed with the SEC a registration statement on Form S-1 under the Securities Act that registers the securities offered under this prospectus. The registration statement, including the attached exhibits and schedules, contains additional relevant information about us and the securities. The rules and regulations of the SEC allow us to omit from this prospectus certain information included in the registration statement.

We are subject to the informational requirements of the Securities Exchange Act and are required to file annual, quarterly and current reports, proxy statements and other information with the SEC. Any information we file with the SEC, including the documents incorporated by reference into this prospectus, is also available on the SEC’s website at www.sec.gov. We also make these documents publicly available, free of charge, on our website at www.aptevotherapeutics.com as soon as reasonably practicable after filing such documents with the SEC. The information contained in, or that can be accessed through, our websitewebsites is not part of this prospectus.prospectus or the registration statement of which this prospectus forms a part, has not been approved and/or endorsed by us or the placement agent and should not be relied upon by investors.

INCORPORATION OF CERTAIN DOCUMENTSINFORMATION BY REFERENCE

The SEC allows us to “incorporate by reference” the information we file with it, which means that we can disclose important information to you by referring you to those documents instead of having to repeat the information in this prospectus. The information incorporated by reference is considered to be part of this prospectus, and because we are a smaller reporting company, later information that we file with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings (including those made after the initial filing of the registration statement of which this prospectus is a part and prior to the effectiveness of such registration statement) we will make with the SEC under Sections 13(a), 13(c), 14, or 15(d) of the Exchange Act until the termination of the offering of the shares covered by this prospectus (other than information furnished under Item 2.02 or Item 7.01 of Form 8-K):

As a smaller reporting company, we also are incorporating by reference any future information filed (rather than furnished) by us with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended, after the date of the initial filing of the registration statement of which this prospectus is a part and before the effective date of the registration statement and after the date of this prospectus until the termination of the offering. Any statements contained in a previously filed document incorporated by reference into this prospectus is deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus, or in a subsequently filed document also incorporated by reference herein, modifies or supersedes that statement.

We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, at no cost, upon written or oral request, a copy of any or all of the reports or documents that have been incorporated by reference in the prospectus contained in the registration statement but not delivered with the prospectus. You should direct requests for documents to:

Aptevo Therapeutics Inc.

2401 4th Avenue, Suite 1050

Seattle, WA 98121

Attn: General Counsel

(206) 838-0500

This prospectus is part of a registration statement we filed with the SEC. That registration statement and the exhibits filed along with the registration statement contain more information about us and the shares in this offering. Because information about documents referred to in this prospectus is not always complete, you should read the full documents which are filed as exhibits to the registration statement. You may read and copy the full registration statement and its exhibits at the SEC’s website.

WHERE YOU CAN FIND MORE INFORMATION

This prospectus is part of a registration statement we filed with the SEC. This prospectus does not contain all of the information set forth in the registration statement and the exhibits to the registration statement. For further information with respect to us and the securities we are offering under this prospectus, we refer you to the registration statement and the exhibits and schedules filed as a part of the registration statement. You should rely only on the information contained in this prospectus or incorporated by reference into this prospectus. We have not authorized anyone else to provide you with different information. We are not making an offer of these securities in any jurisdiction where the offer is not permitted. You should assume that the information contained in this prospectus, or any document incorporated by reference in this prospectus, is accurate only as of the date of those respective documents, regardless of the time of delivery of this prospectus or any sale of our securities.

We are subject to the informational requirements of the Exchange Act and in accordance therewith we file annual, quarterly, and other reports, proxy statements and other information with the Commission under the Exchange Act. Such reports, proxy statements and other information, including the Registration Statement, and exhibits and schedules thereto, are available to the public through the Commission’s website at www.sec.gov.

We make available free of charge on or through our website our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended, as soon as reasonably practicable after we electronically file such material with or otherwise furnish it to the Commission. The registration statement and the documents referred to under “Incorporation of Certain Information by Reference” are also available on our website, https://aptevotherapeutics.gcs-web.com/financial-reports/sec-filings.

We have not incorporated by reference into this prospectus the information on our website, and you should not consider it to be a part of this prospectus.

LEGAL MATTERS

The validity of the securities offered hereby will be passed upon for us by Paul Hastings LLP, Washington, DC. The placement agent is being represented by Ellenoff Grossman & Schole LLP, New York, NY.

EXPERTS

Our consolidated financial statements as of December 31, 2023 and 2022, and for the years then ended, incorporated in this prospectus by reference and included in our Annual Report on Form 10-K for the year ended December 31, 2023, have been audited by Moss Adams LLP, an independent registered public accounting firm, as stated in their report (which report expresses an unqualified opinion and includes an explanatory paragraph related to a going concern uncertainty), which is incorporated herein by reference. Such consolidated financial statements are incorporated by reference in reliance upon the report of such firm given their authority as experts in accounting and auditing.

Up to 7,692,308 Shares of Common Stock or Common Stock Underlying Pre-Funded Warrants

Common Warrants to purchase up to 7,692,308922,509 Shares of Common Stock

Up to 922,509 Pre-Funded Warrants to purchasePurchase up to 7,692,308922,509 Shares of Common Stock

Up to 7,692,3081,845,018 Common Warrants to Purchase up to 1,845,018 Shares of Common Stock Underlying

Up to 2,767,527 Shares of Common Stock underlying the Pre-Funded Warrants and Common Warrants

PRELIMINARY PROSPECTUS

Sole Placement Agent

A.G.P.

, 2023Roth Capital Partners

The date of this prospectus is , 2024.

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 13. Other Expenses of Issuance and Distributions

The following table sets forthindicates the costs and expenses payable by Aptevo Therapeutics Inc. (the “Company”)to be incurred in connection with the offering described in this registration statement, other than underwriting discounts and salecommissions, all of the Common Stock being registered.which will be paid by us. All amounts shown are estimates,estimated except the Securities and Exchange Commission (the “SEC”) registration fee and the FINRA filing fee.

Item 14. Indemnification of Directors and Officers

Section 145 of the Delaware General Corporation Law (the “DGCL”), authorizes a court to award, or a corporation’s board of directors to grant, indemnity to directors and officers in terms sufficiently broad to permit such indemnification under certain circumstances for liabilities, including reimbursement for expenses incurred, arising under the Securities Act of 1933, as amended (the “Securities Act”).

The registrant’s certificate of incorporation and bylaws each provide for indemnification of the registrant’s directors, officers, employees and other agents to the maximum extent permitted by the DGCL.

The registrant has entered into indemnification agreements with its directors and officers whereby it has agreed to indemnify its directors and officers to the fullest extent permitted by law, including indemnification against expenses and liabilities incurred in legal proceedings to which the director or officer was, or is threatened to be made, a party by reason of the fact that such director or officer is or was a director, officer, employee or agent of the registrant, provided that such director or officer acted in good faith and in a manner that the director or officer reasonably believed to be in, or not opposed to, the best interest of the registrant. At present, there is no pending litigation or proceeding involving a director or officer of the registrant regarding which indemnification is sought, nor is the registrant aware of any threatened litigation that may result in claims for indemnification.

The registrant maintains insurance policies that indemnify its directors and officers against various liabilities arising under the Securities Act and the Exchange Act of 1934, as amended, that might be incurred by any director or officer in his or her capacity as such.

Item 15. Recent Sales of Unregistered Securities

Not applicable.We did not sell any unregistered securities during the year ended December 31, 2023.

Item 16. Exhibits and Financial Statement Schedules

(a)Exhibits

Exhibit Index