Skepticism over Fannie Mae’s foray into the single-family rental market has been growing and some lawmakers are voicing their concern. Since announcing the $1 billion deal with Invitation Homes in January, trade groups have expressed anger over Fannie’s pilot program with the Blackstone Group subsidiary, even as Freddie Mac may be next to test the SFR waters. On Feb. 17, 10 Democratic Congressmen sent a letter to Federal Housing Finance Agency Director Mel Watt, asking him to reconsider the deal since it hasn’t been finalized yet. The pilot program is the first time that Fannie backed a large institutional investor. Invitation is the largest single-family rental operator in the U.S. and has a portfolio of about 50,000 homes that it acquires from foreclosures.