These interests include investments in securities issued by VIEs, such as Fannie Mae MBS created pursuant to our securitization transactions. We consolidate the substantial majority of our single-class securitization trusts because our role as guarantor and master servicer provides us with the power to direct matters (primarily the servicing of mortgage loans) that impact the credit risk to which we are exposed. In contrast, we do not consolidate single-class securitization trusts when other organizations have the power to direct these activities unless we have the unilateral ability to dissolve the trust. We also do not consolidate our resecuritization trusts unless we have the unilateral ability to dissolve the trust. Historically, the vast majority of underlying assets of our resecuritization trusts were limited to Fannie Mae securities that were collateralized by mortgage loans held in consolidated trusts. However, with our issuance of UMBS beginning in June 2019, we include securities issued by Freddie Mac in some of our resecuritization trusts. The mortgage loans that serve as collateral for Freddie Mac-issued securities are not held in trusts that are consolidated by Fannie Mae.

Under our lender swap and portfolio securitization transactions, mortgage loans are transferred to a trust specifically for the purpose of issuing a single class of guaranteed securities that are collateralized by the underlying mortgage loans referred to as “first-level securities.” The trust’s permitted activities include receiving the transferred assets, issuing beneficial interests, establishing the guaranty and servicing the underlying mortgage loans. In our capacity as issuer, master servicer, trustee and guarantor, we earn fees for our obligations to each trust. Additionally, we may retain or purchase a portion of the securities issued by each trust.

In our structured securitization transactions, we earn fees for assisting lenders and dealers with the design and issuance of structured mortgage-related securities, referred to as “second-level securities.” In contrast to first-level securities, the trust assets can include both Fannie Mae securities and Freddie Mac securities as the underlying collateral. These structured securities include Fannie Megas^® and Supers^TM, which are single-class resecuritizations, as well as REMICs and SMBS, which are multi-class resecuritizations, and separate the cash flows from underlying assets into separately tradable interests. When we issue a structured security backed in whole or in part by Freddie Mac securities, we provide a new and separate guaranty of principal and interest on the newly-formed structured security. If Freddie Mac were to fail to make a payment due on its securities underlying a Fannie Mae-issued structured security, we would be obligated under our guaranty to fund any shortfall. To the extent that the trust assets are Fannie Mae securities, the trust has permitted activities that are similar to those for our lender swap and portfolio securitization transactions. Additionally, we may retain or purchase a portion of the securities issued by each trust.

We also hold investments in mortgage-backed securities that have been issued via private-label trusts. These trusts are structured to provide investors with a beneficial interest in a pool of receivables or other financial assets, typically mortgage loans. The trusts act as vehicles to allow loan originators to securitize assets. Securities are structured from the underlying pool of assets to provide for varying degrees of risk. The originators of the financial assets or the underwriters of the transaction create the trusts and typically own the residual interest in the trusts’ assets. Our involvement in these entities is typically limited to our recorded investment in the beneficial interests that we have purchased.

In 2018, we resumed making new investments in various limited partnerships that sponsor affordable housing projects utilizing the LIHTC pursuant to Section 42 of the Internal Revenue Code. The purpose of these investments is to increase the supply of affordable housing in the United States and to serve communities in need. In addition, our investments in LIHTC partnerships generate both tax credits and net operating losses that may reduce our federal income tax liability. Our LIHTC investments primarily represent limited partnership interests in entities that have been organized by a fund manager who acts as the general partner. These fund investments seek out equity investments in LIHTC operating partnerships that have been established to identify, develop and operate multifamily housing that is leased to qualifying residential tenants.

We transfer mortgage credit risk to investors through Connecticut Avenue Securities (“CAS”) REMIC and CAS credit-linked note (“CLN”) trusts. In October 2019, we issued our first Multifamily Connecticut Avenue Securities (“MCAS”) transaction, which is a CAS CLN and in December 2019, we issued our first single-family CAS CLN. The structure of CAS CLNs is similar to CAS REMICs; however, CAS CLNs allow us to transfer risk on reference pools containing seasoned loans. Since the REMIC election was not made on the loans in the reference pools at the time of acquisition, these trusts do not qualify as REMICs. Each CAS trust is a separate legal entity which issues notes that are fully collateralized by amounts deposited into a collateral account held by the CAS trust. To the extent that collateral held by the CAS trust and the earnings thereon are insufficient relative to the payments due to holders of the CAS notes, we may be required to make payments to the CAS trust. The CAS trusts qualify as VIEs. We do not have the power to direct significant activities of the CAS trusts while the CAS notes are outstanding, and, therefore, we do not consolidate CAS trusts.

If an entity is a VIE, we consider whether our variable interest in that entity causes us to be the primary beneficiary. The primary beneficiary of the VIE is required to consolidate and account for the assets, liabilities and noncontrolling interests of the VIE in its consolidated financial statements. An enterprise is deemed to be the primary beneficiary when the enterprise has the power to direct the activities of the VIE that most significantly impact the entity’s economic performance and exposure to benefits and/or losses could potentially be significant to the entity. In general, the investors in the obligations of consolidated VIEs have recourse only to the assets of those VIEs and do not have recourse to us, except where we provide a guaranty to the VIE.

We continually assess whether we are the primary beneficiary of the VIEs with which we are involved and therefore may consolidate or deconsolidate a VIE through the duration of our involvement. As of December 31, 2019, we did not consolidate any VIEs that were not already consolidated as of December 31, 2018. However, as of December 31, 2019, we deconsolidated certain VIEs that were consolidated and had combined total assets of $1.5 billion in unpaid principal balance as of December 31, 2018. The majority of this activity related to the deconsolidation of multi-class resecuritization trusts containing consolidated Fannie Mae MBS. This resulted in the recognition of MBS debt outstanding and the fair value of our retained interests as securities in our consolidated balance sheets.

We do not consolidate VIEs when we are not deemed to be the primary beneficiary. Our unconsolidated VIEs include securitization and resecuritization trusts, limited partnerships, and certain SPVs designed to transfer credit risk. The following table displays the carrying amount and classification of our assets and liabilities that relate to our involvement with unconsolidated securitization and resecuritization trusts.



	As of December 31,
	2019				2018
	(Dollars in millions)
Assets and liabilities recorded in our consolidated balance sheets related to unconsolidated mortgage-backed trusts:
Assets:
Trading securities:
Fannie Mae		$	2,543			$	1,422
Non-Fannie Mae		5,100				4,809
Total trading securities		7,643				6,231
Available-for-sale securities:
Fannie Mae		1,524				1,704
Non-Fannie Mae		574				1,207
Total available-for-sale securities		2,098				2,911
Other assets		56				66
Other liabilities		(78		)		(101		)
Net carrying amount		$	9,719			$	9,107

Our maximum exposure to loss generally represents the greater of our recorded investment in the entity or the unpaid principal balance of the assets covered by our guaranty. Our involvement in unconsolidated resecuritization trusts may give rise to additional exposure to loss depending on the type of resecuritization trust. Fannie Mae non-commingled resecuritization trusts are backed entirely by Fannie Mae MBS. These non-commingled single-class and multi-class resecuritization trusts are not consolidated and do not give rise to any additional exposure to loss as we already consolidate the underlying collateral.

Fannie Mae commingled resecuritization trusts are backed in whole or in part by Freddie Mac securities. The guaranty that we provide to these commingled resecuritization trusts may increase our exposure to loss to the extent that we are providing a guaranty for the timely payment and interest on the underlying Freddie Mac securities that we have not previously guaranteed. Our maximum exposure to loss for these unconsolidated trusts is measured by the amount of Freddie Mac securities that are held in these resecuritization trusts. However, a portion of these Freddie Mac securities may be backed in whole or in part by Fannie Mae MBS. To the extent that these Freddie Mac securities are backed by Fannie Mae MBS, our guarantee to the resecuritization trust does not subject us to any additional exposure to credit risk. Thus, our actual exposure to credit risk from Freddie Mac securities held in our resecuritization trusts is likely lower than the disclosed maximum exposure to loss. Our maximum exposure to loss related to unconsolidated securitization and resecuritization trusts was approximately $62 billion and $14 billion as of December 31, 2019 and 2018, respectively. The total assets of our unconsolidated securitization and resecuritization trusts were approximately $130 billion and $80 billion as of December 31, 2019 and 2018, respectively.

The maximum exposure to loss for our unconsolidated limited partnerships and similar legal entities, which consist of LIHTC, community investments and other entities, was $98 million and the related carrying value was $79 million as of December 31, 2019. As of December 31, 2018, the maximum exposure to loss was $111 million and the related carrying value was $89 million. The total assets of these limited partnership investments were $2.0 billion and $2.3 billion as of December 31, 2019 and 2018, respectively.

The maximum exposure to loss related to our involvement with unconsolidated SPVs that transfer credit risk represents the unpaid principal balance and accrued interest payable of obligations issued by the CAS SPVs. The maximum exposure to loss related to these unconsolidated SPVs was $9.5 billion and $920 million as of December 31, 2019 and 2018, respectively. The total assets related to these unconsolidated SPVs were $9.5 billion and $931 million as of December 31, 2019 and 2018, respectively.

The unpaid principal balance of our multifamily loan portfolio was $327.6 billion as of December 31, 2019. As our lending relationship does not provide us with a controlling financial interest in the borrower entity, we do not consolidate these borrowers regardless of their status as either a VIE or a voting interest entity. We have excluded these entities from our VIE disclosures. However, the disclosures we have provided in “Note 3, Mortgage Loans,” “Note 4, Allowance for Loan Losses” and “Note 6, Financial Guarantees” with respect to this population are consistent with the FASB’s stated objectives for the disclosures related to unconsolidated VIEs.

We issue Fannie Mae MBS through portfolio securitization transactions by transferring pools of mortgage loans or mortgage-related securities to one or more trusts or special purpose entities. We are considered to be the transferor when we transfer assets from our own retained mortgage portfolio in a portfolio securitization transaction. For the years ended December 31, 2019, 2018 and 2017, the unpaid principal balance of portfolio securitizations was $278.6 billion, $228.4 billion and $252.7 billion, respectively. The substantial majority of these portfolio securitization transactions generally do not qualify for sale treatment. Portfolio securitization trusts that do qualify for sale treatment primarily consist of loans that are guaranteed or insured, in whole or in part, by the U.S. government.

We retain interests from the transfer and sale of mortgage-related securities to unconsolidated single-class and multi-class portfolio securitization trusts. As of December 31, 2019, the unpaid principal balance of retained interests was $2.9 billion and its related fair value was $4.0 billion. The unpaid principal balance of retained interests was $1.5 billion and its related fair value was $2.2 billion as of December 31, 2018. For the years ended December 31, 2019, 2018 and 2017, the principal, interest and other fees received on retained interests was $595 million, $585 million and $1.1 billion, respectively.