The incredibly shrinking refinance market helped continue the shift in the mix of single-family mortgages securitized by Fannie Mae and Freddie Mac in the month of September, according to a new Inside The GSEs analysis. Fannie and Freddie issued $78.6 billion in single-family mortgage-backed securities in September, a 20.0 percent decline from August, but a 7.0 percent rise for the first nine months of 2013. [Includes one data chart.]