Fannie Mae and Freddie Mac issued a combined $68.91 billion of single-family mortgage-backed securities in April, a 3.8 percent increase over their production in March, according to a new Inside The GSEs ranking and analysis. So far, however, the 2016 market is still lagging by 10.6 percent the production volume during the first four months of last year. While year-to-date purchase-mortgage business was up 12.2 percent for the two GSEs, the refinance market through April was down 24.3 percent from the same period in 2015. Fannie issuance was up 9.9 percent from March, including a 15.4 percent spike in refi activity.