UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10‑K

FORM 10-K

ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 (d) OF THE

SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 20152017

SIMON PROPERTY GROUP, INC.

SIMON PROPERTY GROUP, L.P.

(Exact name of registrant as specified in its charter)

225 West Washington Street
Indianapolis, Indiana 46204
(Address of principal executive offices) (ZIP Code)

(317) 636‑1600
(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the Registrant is a well-knownwell‑known seasoned issuer (as defined in Rule 405 of the Securities Act). Yes ý    No o

Indicate by check mark if the Registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes o    No ý

Indicate by check mark whether the Registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the Registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ý    No o

Indicate by check mark whether the Registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-TS‑T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the Registrant was required to submit and post such files). Yes ý    No o

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of Registrant'sRegistrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. ý☐

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

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 13(a) of the Exchange Act. 

Indicate by check mark whether the Registrant is a shell company (as defined in rule 12-b12‑b of the Act). Yes o    No ý

The aggregate market value of shares of common stock held by non-affiliatesnon‑affiliates of the RegistrantSimon Property Group, Inc. was approximately $53,152$49,945 million based on the closing sale price on the New York Stock Exchange for such stock on June 30, 2015.2017.

As of January 29, 2016,31, 2018, Simon Property Group, Inc. had 314,806,649320,328,774 and 8,000 shares of common stock and Class B common stock outstanding, respectively.

Simon Property Group, L.P. had no publicly-traded voting equity as of June 30, 2017.  Simon Property Group, L.P. has no common stock outstanding.

Documents Incorporated By Reference

Portions of the Registrant'sSimon Property Group, Inc.’s Proxy Statement in connection with its 20162018 Annual Meeting of Stockholders are incorporated by reference in Part III.

Part I

Item 1.Business
Part I

Item 1.    Business

Simon Property Group, Inc., Simon or the Company, is a Delaware corporation that operates as a self-administered and self-managed real estate investment trust, or REIT, under the Internal Revenue Code of 1986, as amended, or the Internal Revenue Code. REITs will generally not be liable for U.S. federal corporate income taxes as long as they distribute not less than 100% of their REIT taxable income. Simon Property Group, L.P., or the Operating Partnership, is our majority-owned Delaware partnership subsidiary that owns all of our real estate properties and other assets. In this discussion,Unless stated otherwise or the terms "we",context otherwise requires, references to "Simon" mean Simon Property Group, Inc. and references to the "Operating Partnership" mean Simon Property Group, L.P.  References to "we," "us" and "our" refer tomean collectively Simon, the Operating Partnership and its subsidiaries.those entities/subsidiaries owned or controlled by Simon and/or the Operating Partnership. According to the Operating Partnership's partnership agreement, the Operating Partnership is required to pay all expenses of Simon.

We own, develop and manage retail real estate properties,premier shopping, dining, entertainment and mixed-use destinations, which consist primarily of Simon®malls, Premium Outlets®Outlets®, and The Mills®Mills®. As of December 31, 2015,2017, we owned or held an interest in 209 income-producing207 income‑producing properties in the United States, which consisted of 108107 malls, 7168 Premium Outlets, 14 Mills, four lifestyle centers, and 1214 other retail properties in 37 states and Puerto Rico. We opened four outlets in 2015 and have three outlets and two other significant retail projects under development. In addition, we have redevelopment and expansion projects, including the addition of anchors, big box tenants, and restaurants, underway at 2925 properties in the U.S.United States, Canada and Europe.Asia. We have one outlet under development in the United States. Internationally, as of December 31, 2015,2017, we had ownership interests in nine Premium Outlets in Japan, threefour Premium Outlets in South Korea, two Premium Outlets in Canada, onetwo Premium OutletOutlets in Mexico,Malaysia, and one Premium Outlet in Malaysia. As of December 31, 2015, we had a noncontrolling ownershipMexico. We also own an interest in a joint venture that holds five outleteight Designer Outlet properties in Europe, of which six properties are consolidated, and one outletDesigner Outlet property in Canada. Of the fiveeight properties in Europe, two are located in Italy, two are located in the Netherlands and one each is located in Austria, the Netherlands,France, Germany and the United Kingdom. Additionally, asWe also have three international outlet properties under development. As of December 31, 2015,2017, we also owned a 20.3%21.0% equity stake in Klépierre SA, or Klépierre, a publicly traded, Paris-basedParis‑based real estate company, which owns, or has an interest in, shopping centers located in 16 countries in Europe.

For a description of our operational strategies and developments in our business during 2015,2017, see Item 7, "Management's“Management’s Discussion and Analysis of Financial Condition and Results of Operations"Operations” of this Form 10-K.10‑K.

Other Policies

The following is a discussion of our investment policies, financing policies, conflict of interest policies and policies with respect to certain other activities. One or more of these policies may be amended or rescinded from time to time without a stockholder vote.

Investment Policies

While we emphasize equity real estate investments, we may also provide secured financing to or invest in equity or debt securities of other entities engaged in real estate activities or securities of other issuers.issuers consistent with Simon’s qualification as a REIT. However, any of these investments would be subject to the percentage ownership limitations and gross income tests necessary for REIT qualification. These REIT limitations mean that weSimon cannot make an investment that would cause ourits real estate assets to be less than 75% of ourits total assets. WeSimon must also derive at least 75% of ourits gross income directly or indirectly from investments relating to real property or mortgages on real property, including "rents“rents from real property,"” dividends from other REITs and, in certain circumstances, interest from certain types of temporary investments. In addition, weSimon must also derive at least 95% of ourits gross income from such real property investments, and from dividends, interest and gains from the sale or dispositions of stock or securities or from other combinations of the foregoing.

Subject to Simon’s REIT limitations, we may invest in the securities of other issuers in connection with acquisitions of indirect interests in real estate. Such an investment would normally be in the form of general or limited partnership or membership interests in special purpose partnerships and limited liability companies that own one or more properties. We may, in the future, acquire all or substantially all of the securities or assets of other REITs, management companies or similar entities where such investments would be consistent with our investment policies.

Financing Policies

Because ourSimon’s REIT qualification requires us to distribute at least 90% of ourits REIT taxable income, we regularly access the debt markets to raise the funds necessary to finance acquisitions, develop and redevelop properties, and refinance maturing debt. We must comply with the covenants contained in our financing agreements that limit our ratio of debt to total assets or market value, as defined. For example, the Operating Partnership's linePartnership’s lines of credit and the indentures for the Operating Partnership'sPartnership’s debt securities contain covenants that restrict the total amount of debt of the Operating Partnership to 65%, or 60% in relation to certain debt, of total assets, as defined under the related agreements, and secured debt to 50% of total assets. In addition, these agreements contain other covenants requiring compliance with financial

unsecured commercial paper notes, denominated in U.S. dollars, EurosEuro and other currencies. Notes issued in non-U.S.non‑U.S. currencies may be issued by one or more subsidiaries of the Operating Partnership and are guaranteed by the Operating Partnership. These notes are sold under customary terms in the U.S. and Euro commercial paper note markets and rank (either by themselves or as a result of the guarantee described above)pari passu with the Operating Partnership'sPartnership’s other unsecured senior indebtedness. The Commercial Paper program is supported by the Credit Facilities and, if necessary or appropriate, we may make one or more draws under either the Credit FacilitiesFacility to pay amounts outstanding from time to time on the Commercial Paper program.

We may also finance our business through the following:

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issuance of shares of common stock or preferred stock;



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issuance of additional common units of limited partnership interest in the Operating Partnership, or units;



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issuance of preferred units of limited partnership interest in the Operating Partnership, or preferred units;



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issuance of other securities including unsecured notes and mortgage debt;



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draws on our Credit Facilities;



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borrowings under the Commercial Paper program; or



•

sale or exchange of ownership interests in properties.

Chairman Emeritus, as well as David Simon's employment agreement, contain covenants limiting their ability to participate in certain shopping center activities.

Policies With Respect To Certain Other Activities

We intend to make investments which are consistent with ourSimon’s qualification as a REIT, unless ourSimon’s Board of Directors determines that it is no longer in ourSimon’s best interests to so qualify as a REIT. OurSimon’s Board of Directors may make such a determination because of changing circumstances or changes in the REIT requirements. We haveSimon has authority to issue shares of ourits capital stock or other securities in exchange for property. We also have authority to repurchase or otherwise reacquire our shares, our units, or any other securities. On April 2, 2015, ourFebruary 13, 2017, Simon’s Board of Directors authorized us to repurchase up toa two-year extension of the previously authorized $2.0 billion of our common stock over a twenty-four month period as market conditions warrant,repurchase plan, or the Repurchase Program.Program, through March 31, 2019. Under the Repurchase Program, weSimon may repurchase the shares in the open market, or in privately negotiated transactions. WeAt December 31, 2017, we had remaining authority to repurchase $1.0 billion of common stock. Simon may also issue shares of ourits common stock, or pay cash at ourits option, to holders of units in future periods upon exercise of such holders'holders’ rights under the partnership agreement of the Operating Partnership. Our policy prohibits us from making any loans to ourthe directors or executive officers of Simon for any purpose. We may make loans to the joint ventures in which we participate. Additionally, we may make or buy interests in loans secured by real estate properties owned by others or make investments in companies that own real estate assets.

Competition

The retail real estate industry is dynamic and competitive. We compete with numerous merchandise distribution channels, including malls, outlet centers, community/lifestyle centers, and other shopping centers in the United States and abroad. We also compete with internet retailing sites and catalogs which provide retailers with distribution options beyond existing

Employees

At December 31, 2015,2017, we and our affiliates employed approximately 5,000 persons at various properties and offices throughout the United States, of which approximately 1,8501,700 were part-time.part‑time. Approximately 1,1001,000 of these employees were located at our corporate headquarters in Indianapolis, Indiana.

Corporate Headquarters

Our corporate headquarters are located at 225 West Washington Street, Indianapolis, Indiana 46204, and our telephone number is (317) 636-1600.

Mr. Sokolov has served as President and Chief Operating Officer of Simon or its predecessor since 1996. Mr. Sokolov has also been a director of Simon or its predecessor since 1996. Mr. Sokolov was President and Chief Executive Officer of DeBartolo Realty Corporation from its incorporation in 1994 until it merged with our predecessors in 1996. Mr. Sokolov joined its predecessor, The Edward J. DeBartolo Corporation, in 1982 as Vice President and General Counsel and was named Senior Vice President, Development and General Counsel in 1986.

Mr. Juster serves as Simon'sSimon’s Executive Vice President and Chief Financial Officer. Mr. Juster joined Melvin Simon & Associates, Inc., or MSA, in 1989 and held various financial positions with MSA until 1993 and thereafter has held various positions with Simon. Mr. Juster became Treasurer in 2001 and was promoted to Executive Vice President in 2008 and Chief Financial Officer in 2014.

            Mr. Contis serves as Simon's Senior Executive Vice President and President of Simon Malls. Mr. Contis joined Simon in 2011. Prior to joining Simon, Mr. Contis served as the President of Real Estate at Equity Group Investments, LLC. Mr. Contis has over 35 years of domestic and international real estate experience including 25 years overseeing both public and private mall portfolios.

Item 1A.  Risk Factors

The following factors, among others, could cause our actual results to differ materially from those containedexpressed or implied in forward-lookingforward‑looking statements made in this Annual Report on Form 10-K10‑K and presented elsewhere by our management from time to time. These factors may have a material adverse effect on our business, financial condition, liquidity, results of operations, funds from operations, or FFO, and prospects, which we refer to herein as a material adverse effect on us or as materially and adversely affecting us, and you should carefully consider them. Additional risks and uncertainties not presently known to us or which are currently not believed to be material may also affect our actual results. We may update these factors in our future periodic reports.

Risks Relating to Retail Operations

Overall economic and market conditions may adversely affect the general retail environment.

Our concentration in the retail real estate market means that we are subject to a number of factors that could adversely affect the retail environment generally, including, without limitation:

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changes in international, national, regional and local economic conditions;



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local real estate conditions, such as an oversupply of, or reduction in demand for, retail space or retail goods, decreases in rental rates, declining real estate values and the availability and creditworthiness of tenants;



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levels of consumer spending, changes in consumer confidence and fluctuations in seasonal spending;



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the willingness of retailers to lease space in our properties;



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tenant bankruptcies and a resulting rejection of our leases;



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the impact on our retail tenants and demand for retail space at our properties from the increasing use of the Internet by retailers and consumers;



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perceptions by consumers of the safety, convenience and attractiveness of our properties;



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increased operating costs;



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changes in applicable laws and regulations, including tax, environmental, safety and zoning;



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casualties and other natural disasters; and



•

the potential for terrorist activities.

We derive our operating results primarily from retail tenants, many of whom have been and continue to be under some degree of economic stress. A significant deterioration in the creditworthiness of our retail tenants could have a material adverse effect on us.

             We may not be able to lease newly developed properties and renew leases and relet space at existing properties.

            We may not be able to lease new properties to an appropriate mix of tenants. Also, when leases for our existing properties expire, the premises may not be relet or the terms of reletting, including the cost of allowances and concessions to tenants, may be less favorable than the current lease terms. To the extent that our leasing goals are not achieved, we could be materially and adversely affected.

Some of our properties depend on anchor stores or other major tenants to attract shoppers and could be adversely affected by the loss of one or more of these anchor stores or major tenants.

Our properties are typically anchored by department stores and other large nationally recognized tenants. The value of some of our properties could be materially and adversely affected if these anchors or other major tenants fail to comply with their contractual obligations or cease their operations.

For example, among department stores and other large stores — often referred to as "big box"“big box” stores — corporate merger activity typically results in the closure of duplicate or geographically overlapping store locations. Further, sustained adverse pressure on the results of our department stores and major tenants may have a similarly sustained adverse impact upon our own results. Certain department stores and other national retailers have experienced, and may continue to experience for the foreseeable future given current macroeconomic uncertainty and less-than-desirableless‑than‑desirable levels of consumer

may be entitled to modify the economic or other terms of, or terminate, their existing leases with us in the event of such closures.

If a department store or major tenant were to close its stores at our properties, we may experience difficulty and delay and incur significant expense in replacing the tenant, as well as in leasing spaces in areas adjacent to the vacant department store or major tenant, at attractive rates, or at all. Additionally, department store or major tenant closures may result in decreased customer traffic, which could lead to decreased sales at our properties. If the sales of stores operating in our properties were to decline significantly due to the closing of anchor stores or other national retailers, adverse economic conditions, or other reasons, tenants may be unable to pay their minimum rents or expense recovery charges. In the event of any default by a tenant, we may not be able to fully recover, and/or may experience delays and costs in enforcing our rights as landlord to recover, amounts due to us under the terms of our agreements with such parties.

We face potential adverse effects from tenant bankruptcies.

Bankruptcy filings by retailers can occur regularly in the course of our operations. If a tenant files for bankruptcy, the tenant may have the right to reject and terminate one or more of its leases with us, and we cannot be sure that it will affirm one or more of its leases and continue to make rental payments to us in a timely manner. A bankruptcy filing by, or relating to, one of our tenants would bar all efforts by us to collect pre-bankruptcypre‑bankruptcy debts from that tenant, or from their property, unless we receive an order permitting us to do so from the bankruptcy court. In addition, we cannot evict a tenant solely because of its bankruptcy. If a lease is assumed by the tenant in bankruptcy, all pre-bankruptcypre‑bankruptcy balances due under the lease must be paid to us in full. However, if a lease is rejected by a tenant in bankruptcy, we would have only a general unsecured claim for damages in connection with such balances. If a bankrupt tenant vacates a space, it might not do so in a timely manner, and we might be unable to re-leasere‑lease the vacated space during that time at attractive rates, or at all. Furthermore, we may be required to incur significant expense in replacing the bankrupt tenant. Any unsecured claim we hold against a bankrupt tenant might be paid only to the extent that funds are available and only in the same percentage as is paid to all other holders of unsecured claims, and there are restrictions under bankruptcy laws that limit the amount of the claim we can make if a lease is rejected. As a result, it is likely that we would recover substantially less than the full value of any unsecured claims we hold. We continually seek to re-leasere‑lease vacant spaces resulting from tenant terminations. The bankruptcy of a tenant, particularly an anchor tenant or a national tenant with multiple locations, may make the re-leasingre‑leasing of their space difficult and costly, and it also may be more difficult to lease the remainder of the space at the affected properties. Future tenant bankruptcies may impact our ability to successfully execute our re-leasingre‑leasing strategy and could materially and adversely affect us.

We face a wide range of competition that could affect our ability to operate profitably.

Our properties compete with other retail properties and other forms of retailing such as catalogs and e-commercee‑commerce websites. Competition may come from malls, outlet centers, community/lifestyle centers, and other shopping centers, both existing as well as future development and redevelopment/expansion projects, as well as catalogs and e-commerce.e‑commerce. The presence of competitive alternatives affects our ability to lease space and the level of rents we can obtain. New construction, renovations and expansions at competing sites could also negatively affect our properties.

We also compete with other major real estate investors and developers for attractive investment opportunities and prime development sites. Competition for the acquisition of existing properties and development sites may result in increased purchase prices and may adversely affect our ability to make attractive investments on favorable terms, or at all. In addition, we compete with other retail property companies for tenants and qualified management.

We may not be able to lease newly developed properties and renew leases and relet space at existing properties.

We may not be able to lease new properties to an appropriate mix of tenants. Also, when leases for our existing properties expire, the premises may not be relet or the terms of reletting, including the cost of allowances and concessions to tenants, may be less favorable than the current lease terms. To the extent that our leasing goals are not achieved, we could be materially and adversely affected.

Risks Relating to Real Estate Investments and Operations

Our international activities may subject us to different or greater risk from those associated with our domestic operations.

As of December 31, 2017, we held interests in consolidated and joint venture properties that operate in Austria, France, Italy, Germany, Japan, Malaysia, Mexico, the Netherlands, South Korea, Canada, and the United Kingdom. We also have an equity stake in Klépierre, a publicly‑traded European real estate company, which operates in 16 countries in Europe. Accordingly, our operating results and the value of our international operations may be impacted by any unhedged movements in the foreign currencies in which those operations transact and in which our net investment in the international operation is held. We may pursue additional investment, development and redevelopment/expansion opportunities outside the United States. International investment, ownership, development and redevelopment/expansion activities carry risks that are different from those we face with our domestic properties and operations. These risks include, but are not limited to:

Our international activities represented approximately 5.1% of consolidated net income and 9.0% of our net operating income, or NOI, for the year ended December 31, 2017. To the extent that we expand our international activities, the above risks could increase in significance, which in turn could have a material adverse effect on us.

We are subject to numerous laws and regulations that could adversely affect our operations or expose us to liability.

Our properties are subject to numerous federal, state and local laws and regulations, some of which may conflict with one another or be subject to varying judicial or regulatory interpretations. These laws and regulations may include zoning laws, building codes, competition laws, rules and agreements, landlord-tenant laws, property tax regulations, changes in real estate assessments and other laws and regulations generally applicable to business operations. Noncompliance with such laws and regulations, and any associated litigation could expose us to liability.

We face risks associated with the acquisition, development, redevelopment and expansion of properties.

We regularly acquire and develop new properties and redevelop and expand existing properties, and these activities are subject to various risks. We may not be successful in pursuing acquisition, development or redevelopment/expansion opportunities. In addition, newly acquired, developed or redeveloped/expanded properties may not perform as well as

If a development or redevelopment/expansion project is unsuccessful, either because it is not meeting our expectations when operational or was not completed according to the project planning, we could lose our investment in the project. Further, if we guarantee the property'sproperty’s financing, our loss could exceed our investment in the project.

Real estate investments are relatively illiquid.

Our properties represent a substantial portion of our total consolidated assets. These investments are relatively illiquid. As a result, our ability to sell one or more of our properties or investments in real estate in response to any changes in economic, industry, or other conditions may be limited. The real estate market is affected by many factors, such as general economic conditions, availability and terms of financing, interest rates and other factors, including supply and demand for space, that are beyond our control. If we want to sell a property, we cannot assure you that we will be able to dispose of it in the desired time period or at all or that the sales price of a property will be attractive at the relevant time or even exceed the carrying value of our investment. Moreover, if a property is mortgaged, we may not be able to obtain a release of the lien on that property without the payment of the associated debt and/or a substantial prepayment penalty, which could restrict our ability to dispose of the property, even though the sale might otherwise be desirable.

             Our international activities may subject us to different or greater risk from those associated with our domestic operations.

            As of December 31, 2015, we held interests in joint venture properties that operate in Austria, Italy, Japan, Malaysia, Mexico, the Netherlands, South Korea, Canada, and the United Kingdom. We also have an equity stake in Klépierre, a publicly-traded European real estate company which operates in 16 countries in Europe. Accordingly, our operating results and the value of our international operations may be impacted by any unhedged movements in the foreign currencies in which those operations transact and in which our net investment in the international operation is held. We may pursue additional investment, development and redevelopment/expansion opportunities outside the United States. International investment, ownership, development and redevelopment/expansion activities carry risks that are different from those we face with our domestic properties and operations. These risks include, but are not limited to:

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adverse effects of changes in exchange rates for foreign currencies;



•

changes in foreign political and economic environments, regionally, nationally, and locally;



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challenges of complying with a wide variety of foreign laws, including corporate governance, operations, taxes and litigation;



•

differing lending practices;



•

differences in cultures;



•

changes in applicable laws and regulations in the United States that affect international operations;



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difficulties in managing international operations; and



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obstacles to the repatriation of earnings and cash.

            Our international activities represented approximately 7.9% of our net operating income, or NOI, for the year ended December 31, 2015. To the extent that we expand our international activities, the above risks could increase in significance, which in turn could have a material adverse effect on us.

viewed by the credit rating agencies as relevant to our industry and the economic outlook in general. Our credit rating can affect the amount of capital we can access, as well as the terms of any financing we obtain. Since we depend primarily on debt financing to fund the growth of our business, an adverse change in our credit rating, including actual changes and changes in outlook, or even the initiation of a review of our credit rating that could result in an adverse change, could have a material adverse effect on us.

The agreements that govern our indebtedness contain various covenants that impose restrictions on us that might affect our ability to operate freely.

We have a variety of unsecured debt, including the Credit Facilities, and secured property-levelproperty‑level debt. Certain of the agreements that govern our indebtedness contain covenants, including, among other things, limitations on our ability to incur secured and unsecured indebtedness, sell all or substantially all of our assets and engage in mergers and certain acquisitions. In addition, certain of the agreements that govern our indebtedness contain financial covenants that require us to maintain certain financial ratios, including certain coverage ratios. These covenants may restrict our ability to pursue certain business initiatives or certain transactions that might otherwise be advantageous to us. In addition, our ability to comply with these provisions might be affected by events beyond our control. Failure to comply with any of our financing covenants could result in an event of default, which, if not cured or waived, could accelerate the related indebtedness as well as other of our indebtedness, which could have a material adverse effect on us.

weAny such corporate tax liability could be substantial and would reduce the amount of cash available for, among other things, our operations and distributions to stockholders. In addition, if Simon fails to qualify as a REIT, it will not be allowed a deduction forrequired to make distributions to stockholders in computing our REIT taxable income;

Complying with REIT requirements might cause us to forego otherwise attractive acquisition opportunities or liquidate otherwise attractive investments.

To qualify to be taxed as a REITREITs for U.S. federal income tax purposes, weSimon and certain subsidiaries of the Operating Partnership must ensure that, at the end of each calendar quarter, at least 75% of the value of ourtheir respective assets consist of cash, cash items, government securities and "real“real estate assets"assets” (as defined in the Internal Revenue Code), including certain mortgage loans and securities. The remainder of ourtheir respective investments (other than government securities, qualified real estate assets and securities issued by a taxable REIT subsidiary, or TRS) generally cannot include more than 10% of the outstanding voting securities of any one issuer or more than 10% of the total value of the outstanding securities of any one issuer.

Additionally, in general, no more than 5% of the value of ourSimon’s and these subsidiaries’ total assets (other than government securities, qualified real estate assets and securities issued by a TRS) can consist of the securities of any one issuer, and no more than 25% (20% for taxable years beginning after December 31, 2017) of the value of ourtheir respective total assets can be represented by securities of one or more TRSs. If we failSimon or any of these subsidiaries fails to comply with these requirements at the end of any calendar quarter, weSimon or any such subsidiary must correct the failure within 30 days after the end of the calendar quarter or qualify for certain statutory relief provisions to avoid losing ourits REIT qualification and suffering adverse tax consequences. As a result, we might be required to liquidate or forego otherwise attractive investments. These actions could have the effect of reducing our income and amounts available for distribution to our stockholders.equity holders.

In addition to the asset tests set forth above, to qualify to be taxed as a REIT, weREITs, Simon and these subsidiaries must continually satisfy tests concerning, among other things, the sources of ourtheir respective income, the amounts wethey distribute to our stockholdersequity holders and the ownership of ourtheir respective shares. We might be unable to pursue investments that would be otherwise advantageous to us in order to satisfy the source-of-incomesource‑of‑income or asset-diversificationasset‑diversification requirements for qualifying as a REIT.REITs. Thus, compliance with the REIT requirements may hinder our ability to make certain attractive investments.

             New partnershipPartnership tax audit rules could have a material adverse effect on us.

The recently enacted Bipartisan Budget Act of 2015 changes the rules applicable to U.S. federal income tax audits of partnerships. Under the new rules (which are generally effective for taxable years beginning after December 31, 2017), among other changes and subject to certain exceptions, any audit adjustment to items of income, gain, loss, deduction, or credit of a partnership (and any partner'spartner’s distributive share thereof) is determined, and taxes, interest, or penalties attributable thereto arecould be assessed and collected, at the partnership level. Although it is uncertain how these new rules will be implemented, it is possible that they could result in partnerships in which we directly or indirectindirectly invest, being required to pay additional taxes, interest and penalties as a result of an audit adjustment, and we, as a direct or indirect partner of these partnerships, could be required to bear the economic burden of those taxes, interest, and penalties even though we,Simon and certain subsidiaries of the Operating Partnership, as a REIT,REITs, may not otherwise have been required to pay additional corporate-levelcorporate‑level taxes had wethey owned the assets of the partnership directly. The new partnership tax audit rules will apply to the Operating Partnership and its subsidiaries that are classified as partnerships for U.S. federal income tax purposes. The changes created by these new rules are sweeping and in many respects dependent on the promulgation of future regulations or other guidance by the U.S. Department of the Treasury, or the Treasury, and, accordingly, there can be no assurance that these rules will not have a material adverse effect on us.

Legislative, administrative, regulatory or other actions affecting REITs, including positions taken by the IRS, could have a material adverse effect on us orand our investors.

The rules dealing with U.S. federal income taxation are constantly under review by persons involved in the legislative process, and by the IRS and the U.S. Department of the Treasury, or the Treasury. Changes to the tax laws or interpretations thereof by the IRS and the Treasury, with or without retroactive application, could materially and adversely affect us orand our investors. New legislation (including the recently enacted Tax Cuts and Jobs Act and any technical corrections legislation), Treasury regulations, administrative interpretations or court decisions could significantly and negatively affect ourthe ability of Simon and certain subsidiaries of the Operating Partnership to qualify to be taxed as a REITREITs and/or the U.S. federal income tax consequences to us and our investors of such qualification.

Risks Relating to Joint Ventures

We have limited control with respect to some properties that are partially owned or managed by third parties, which may adversely affect our ability to sell or refinance them.

As of December 31, 2015,2017, we owned interests in 94 income-producing100 income‑producing properties with other parties. Of those, 1319 properties are included in our consolidated financial statements. We account for the other 81 properties, or the joint venture properties, as well as our investmentinvestments in Klépierre (a publicly traded, Paris-based real estate company), Aéropostale, and our joint ventures with Seritage GrowthHBS Global Properties, or Seritage, and Hudson's Bay Company, or HBC,HBS, using the equity method of accounting. We serve as general partner or property manager for 58 of these 81 joint venture properties; however, certain major decisions, such as approving the operating budget and selling, refinancing and redeveloping the properties, require the consent of the other owners. Of the joint venture properties for which we do not serve as general partner or property manager, 2019 are in our international joint ventures. TheThese international properties are managed locally by joint ventures in which we share control of the properties with our partner. The other owners have participating rights that we consider substantive for purposes of determining control over the properties'joint venture properties’ assets. The remaining joint venture properties, Klépierre, (a publicly traded, Paris-based real estate company), and our joint ventureventures with HBCAéropostale and HBS, are managed by third parties.

These investments, and other future similar investments could involve risks that would not be present were a third party not involved, including the possibility that partners or other owners might become bankrupt, suffer a deterioration in their creditworthiness, or fail to fund their share of required capital contributions. Partners or other owners could have economic or other business interests or goals that are inconsistent with our own business interests or goals, and could be in a position to take actions contrary to our policies or objectives.

These investments, and other future similar investments, also have the potential risk of creating impasses on decisions, such as a sale or financing, because neither we nor our partner or other owner has full control over the partnership or joint venture. Disputes between us and partners or other owners might result in litigation or arbitration that could increase our expenses and prevent ourSimon’s officers and/or directors from focusing their time and efforts on our business. Consequently, actions by, or disputes with, partners or other owners might result in subjecting properties owned by the partnership or joint venture to additional risk. In addition, we risk the possibility of being liable for the actions of our partners or other owners.

The Operating Partnership guarantees debt or otherwise provides support for a number of joint venture properties.

Joint venture debt is the liability of the joint venture and is typically secured by a mortgage on the joint venture property, which is non-recoursenon‑recourse to us. Nevertheless, the joint venture'sventure’s failure to satisfy its debt obligations could result in the loss of our investment therein. As of December 31, 2015,2017, the Operating Partnership guaranteed joint venture related mortgage indebtedness of $353.7$211.6 million (of which we have a right of recovery from our joint venture partners of $112.8$10.8 million). A default by a joint venture under its debt obligations maywould expose us to liability under a guaranty. We may elect to fund cash needs of a joint venture through equity contributions (generally on a basis proportionate to our ownership interests), advances or partner loans, although such fundings are not typically required contractually or otherwise.

Risks Relating to Environmental Matters

As owners of real estate, we can face liabilities for environmental contamination.

            Federal,U.S. federal, state and local laws and regulations relating to the protection of the environment may require us, as a current or previous owner or operator of real property, to investigate and clean up hazardous or toxic substances or petroleum product releases at a property or at impacted neighboring properties. These laws often impose liability regardless of whether the property owner or operator knew of, or was responsible for, the presence of hazardous or toxic substances. These laws and regulations may require the abatement or removal of asbestos containing materials in the event of damage, demolition or renovation, reconstruction or expansion of a property and also govern emissions of and exposure to asbestos fibers in the air. Those laws and regulations also govern the installation, maintenance and removal of underground storage tanks used to store waste oils or other petroleum products. Many of our properties contain, or at one time contained, asbestos containing materials or underground storage tanks (primarily related to auto service center establishments or emergency electrical generation equipment). We may be subject to regulatory action and may also be held liable to third parties for personal injury or property damage incurred by the parties in connection with any such laws and regulations or hazardous or toxic substances. The costs of investigation, removal or remediation of hazardous or toxic substances, and related liabilities, may be substantial and could materially and adversely affect us. The presence of hazardous or toxic

substances, or the failure to remediate the related contamination, may also adversely affect our ability to sell, lease or redevelop a property or to borrow money using a property as collateral.

A breach or significant and extended disruption in the functioning of our systems, including our primary website, could damage our reputation and cause us to lose customers, tenants and revenues, generate third party claims, result in the unintended and/or unauthorized public disclosure or the misappropriation of proprietary, personal identifying and confidential information, and require us to incur significant expenses to address and remediate or otherwise resolve these kinds of issues, and we may not be able to recover these expenses in whole or in any part from our service providers or responsible parties, or their or our insurers.

Our success depends, in part, on our ability to attract and retain talented employees, and the loss of any one of our key personnel could adversely impact our business.

The success of our business depends, in part, on the leadership and performance of our executive management team and key employees, and our ability to attract, retain and motivate talented employees could significantly impact our future performance. Competition for these individuals is intense, and we cannot assure you that we will retain our key executive management team and other key employees or that we will be able to attract and retain other highly qualified individuals for these positions in the future. Losing any one or more of these persons could have a material adverse effect on us.

Provisions in ourSimon’s charter and by-lawsby‑laws and in the Operating Partnership'sPartnership’s partnership agreement could prevent a change of control.

            OurSimon’s charter contains a general restriction on the accumulation of shares in excess of 8% of ourits capital stock. The charter permits the members of the Simon family and related persons to own up to 18% of ourSimon’s capital stock. Ownership is determined by the lower of the number of outstanding shares, voting power or value controlled. OurSimon’s Board of Directors may, by majority vote, permit exceptions to those levels in circumstances where ourSimon’s Board of Directors determines ourthat Simon’s ability to qualify as a REIT will not be jeopardized. These restrictions on ownership may have the effect of delaying, deferring or preventing a transaction or a change in control that might otherwise be in the best interest of our stockholders.Simon’s stockholders or the Operating Partnership’s unitholders or preferred unitholders. Other provisions of ourSimon’s charter and by-lawsby‑laws could have the effect of delaying or preventing a change of control even if some of Simon’s stockholders or the Operating Partnership’s unitholders or preferred unitholders deem such a change to be in their best interests. These include provisions preventing holders of ourSimon’s common stock from acting by written consent and requiring that up to four directors in the aggregate may be elected by holders of Class B common stock. In addition, certain provisions of the Operating Partnership'sPartnership’s partnership agreement could have the effect of delaying or preventing a change of control. These include a provision requiring the consent of a majority in interest of units in order for us,Simon, as general partner of the Operating Partnership, to, among other matters, engage in a merger transaction or sell all or substantially all of ourits assets.

We face possible risks associated with climate change.

We cannot determine with certainty whether global warming or cooling is occurring and, if so, at what rate. To the extent climate change causes changes in weather patterns, our properties in certain markets could experience increases in storm intensity and rising sea‑levels. Over time, these conditions could result in volatile or decreased demand for retail space at certain of our properties or, in extreme cases, our inability to operate the properties at all. Climate change may also have indirect effects on our business by increasing the cost of (or making unavailable) insurance on favorable terms, or at all, and increasing the cost of energy and snow removal at our properties. Moreover, compliance with new laws or regulations related to climate change, including compliance with “green” building codes, may require us to make improvements to our existing properties or increase taxes and fees assessed on us or our properties. At this time, there can be no assurance that climate change will not have a material adverse effect on us.

The United Kingdom’s pending departure from the European Union could have a material adverse effect on us.

Following a national referendum in June 2016, the United Kingdom formally notified the European Council on March 29, 2017 of its intention to withdraw from the European Union (“EU”) (commonly referred to as “Brexit”).  Negotiations have commenced to determine the future terms of the United Kingdom’s relationship with the EU, including, among other things, the terms of trade between the United Kingdom and the EU. However, the terms of any agreement governing the future relationship between the United Kingdom and the EU, as well as the legal and economic consequences of those terms, remain unclear. This continues to create political and economic uncertainty, which has affected, and may continue to affect, market and macro-economic conditions in both the United Kingdom and EU economies. In particular, prolonged uncertainty

during Brexit negotiations may contribute to ongoing volatility in financial and foreign exchange markets in the United Kingdom and EU, including a fall in gross domestic product and volatility in the value of Pounds Sterling.

Brexit could also contribute to greater volatility in global financial and foreign exchange markets after the terms of the United Kingdom’s future relationships with the EU are settled. Further, financial and other markets may suffer losses as a result of any other countries determining to withdraw from the EU or from any future significant changes to the EU’s structure and/or regulations.

We currently hold, and may acquire additional, equity interests in properties located in the United Kingdom and Europe, as well as other investments that are denominated in Pounds Sterling and Euro. In addition, our Operating Partnership has issued, and may issue in the future, senior unsecured notes denominated in Euro. Any of the effects of Brexit described above, and others we cannot anticipate, could have a material adverse effect on us, including the value of our properties and investments and our potential growth in Europe, and could amplify the currency risks faced by us.

Item 1B.  Unresolved Staff Comments

None.

Item 2.  Properties

United States Properties

Our U.S. properties primarily consist of malls, Premium Outlets, The Mills, lifestyle centers and other retail properties. These properties contain an aggregate of approximately 184.2182.3 million square feet of gross leasable area, or GLA.

Malls typically contain at least one traditional department store anchor or a combination of anchors and big box retailers with a wide variety of smaller stores connecting the anchors. Additional stores are usually located along the perimeter of the parking area. Our 108107 malls are generally enclosed centers and range in size from approximately 465,000260,000 to 2.62.7 million square feet of GLA. Our malls contain in the aggregate more than 13,70013,200 occupied stores, including approximately 517500 anchors, which are predominately national or international retailers.

Premium Outlets generally contain a wide variety of designer and manufacturer stores located in open-airopen‑air centers. Our 7168 Premium Outlets range in size from approximately 150,000 to 870,000900,000 square feet of GLA. The Premium Outlets are generally located within a close proximity to major metropolitan areas and/or tourist destinations.

The 14 properties in The Mills generally range in size from 1.2 million to 2.3 million square feet of GLA and are located in major metropolitan areas. They have a combination of traditional mall, outlet center, and big box retailers and entertainment uses.

We also have interests in four lifestyle centers and 1214 other retail properties. The lifestyle centers range in size from 160,000 to 900,000 square feet of GLA. The other retail properties range in size from approximately 150,000160,000 to 730,000890,000 square feet of GLA and are considered non-corenon‑core to our business model. In total, the lifestyle centers and other retail properties represent approximately 1.0%0.6% of our total operating income before depreciation and amortization.NOI.

As of December 31, 2015,2017, approximately 96.1%95.6% of the owned GLA in malls and Premium Outlets was leased and approximately 98.5%98.4% of the owned GLA for The Mills was leased.

We wholly own 137134 of our properties, effectively control 13 properties in which we have a joint venture interest, and hold the remaining 5960 properties through unconsolidated joint venture interests. We are the managing or co-managingco‑managing general partner or member of 206203 properties in the United States. Certain of our joint venture properties are subject to various rights of first refusal, buy-sellbuy‑sell provisions, put and call rights, or other sale or marketing rights for partners which are customary in real estate partnership agreements and the industry. We and our partners in these joint ventures may initiate these provisions (subject to any applicable lock up or similar restrictions) which may result in either the sale of our interest or the use of available cash or borrowings, or the use of Operating Partnership units, to acquire the joint venture interest from our partner.

On April 13, 2015, we announced a joint venture with Sears Holdings, or Sears, whereby Sears contributed 10 of its properties located at our malls to the joint venture in exchange for a 50% noncontrolling interest in the joint venture.  Seritage Growth Properties, or Seritage, a public REIT recently formed by Sears, now holds Sears'Sears’ interest in the joint venture.

 On November 3, 2017, we acquired additional interests in the real estate assets and/or rights to terminate leases related to twelve Sears stores located at our malls (including five stores previously held in our joint venture with Seritage), in order to redevelop these properties.  Four of the Sears stores are at properties held in unconsolidated joint ventures.  Our joint venture with Seritage now covers the former Sears properties located at five of our malls.