New issuance of single-family mortgage-backed securities by Fannie Mae and Freddie Mac fell sharply in the fourth quarter of 2015 despite a December rebound in monthly volume, according to a new Inside Mortgage Finance analysis and ranking. The two government-sponsored enterprises issued $179.01 billion of single-family MBS during the final three months of 2015, a 19.9 percent drop from the third quarter. It was the weakest level of new business for the GSEs since the second quarter of 2014. A faltering purchase-mortgage market was...[Includes three data tables]