Declining refinance volume contributed to a marked decline in the GSEs’ overall business during September compared to the previous month, with Fannie Mae seeing a rise volume to the detriment of Freddie Mac, according to a new Inside The GSEs analysis.Fannie and Freddie issued $78.6 billion in single-family mortgage-backed securities during the third quarter, a 20.0 percent decline from August but a 9.0 percent rise for the first nine months of 2013. [Includes one data chart.]