A sharp downturn in refinance activity reduced Fannie Mae’s and Freddie Mac’s business volume during the second quarter of 2013, but the GSEs posted their strongest quarter in purchase-mortgage activity in four years, according to a new Inside The GSEs analysis. Fannie and Freddie issued $337.74 billion in single-family mortgage-backed securities during the second quarter, a 5.1 percent decline from the first three months of the year. The decline put an end to an upward trend in GSE production that took hold during the third quarter of 2012. Despite this, Fannie and Freddie business was up 20.0 percent over the first six months of last year.