Fannie Mae Mortgage Association, or FNMA, is a U.S. government sponsored enterprise that focuses on expanding housing opportunities across the United States. To do so, it purchases residential mortgages from lenders and securitizes, or pools them, into mortgage-backed securities. While Fannie Mae does not offer direct commercial real estate loans, investors can rent a certain amount of commercial space if they use an FNMA loan to purchase a multifamily property. For example, apartments purchased with a Fannie Mae DUS loan are permitted to have up to 35% of their property's space occupied by commercial tenants. Or, they can derive 20% of the property's income from commercial sources (whichever is less).
In addition to Fannie Mae, its brother corporation, Freddie Mac, also purchases and insures multifamily mortgages, including some that allow for a degree of commercial property use. For example, properties purchased with a Freddie Mac Small Balance Loan (SBL), can derive up to 40% of their income from commercial rents.