A sustained decline in GSE refinances, coupled with faltering purchase activity throughout the first quarter, helped contribute to an overall drop in the volume of single-family mortgages securitized by Fannie Mae and Freddie Mac in March. In the first quarter of 2014, Fannie and Freddie combined for $355.8 billion in new single-family securitizations, down 63.7 percent year-to-date.In March, Fannie and Freddie produced just $37.6 billion of single-family MBS, down 15.6 percent from February. It was the lowest monthly volume since January 2009.