Fannie Mae and Freddie Mac in June rebounded from a decline the previous month with a big boost in the volume of single-family mortgages securitized by the two GSEs, according to a new Inside The GSEs analysis. Fannie and Freddie issued $51.6 billion in single-family mortgage-backed securities in June, a 15.2 percent jump from the previous month. Year-to-date MBS issuance was down 60.9 percent from the same period a year ago.