Real estate investment trusts that focus on the MBS market recorded a modest increase in their MBS holdings during the first quarter of 2017, according to an Inside MBS & ABS analysis. And observers say a pending change in how Fannie Mae and Freddie Mac structure their credit-risk transfer programs may boost REIT participation further. The 15 mortgage REITs tracked by Inside MBS & ABS reported a combined $230.82 billion of MBS investment at the end of March, including assets held in the to-be-announced market. That was up 1.6 percent from the end of 2016, though it was still off from year-ago levels. Some 91.8 percent of REIT MBS holdings are...[Includes one data table]