"Multifamily properties—those with five or more units— provide shelter for approximately one-third of the more than 100 million renters in the United States and account for about 14 percent of all housing units. Mortgages carrying an actual or implied federal guarantee have been an important source of financing for acquiring, developing, and rehabilitating multifamily properties, particularly after the collapse in house prices and credit availability that accompanied the 2008–2009 recession. According to the Federal Reserve, the share of outstanding multifamily mortgages carrying such a guarantee increased by 10 percentage points, from 33 percent at the beginning of 2005 to 43 percent at the end of the third quarter of 2014. (A slightly larger increase of about 16 percentage points occurred in the federal government’s market share of the much larger single-family market.) Such guarantees are made by a variety of entities, and some policymakers are looking for ways to make the federal government’s involvement more effective. Other policymakers have expressed concern about that expanded federal role and are looking at ways to reduce it..."