The purchase-mortgage business showed some green shoots in April, but not enough to offset another drop in refinance activity, according to a new Inside The GSEs ranking and analysis. Fannie Mae and Freddie Mac securitized $31.84 billion of purchase mortgages last month, a 12.2 percent increase from March. It was the third straight monthly gain in purchase-mortgage volume, bringing year-to-date activity to $123.46 billion, a 13.6 percent improvement over the same period in 2016. Purchase mortgages accounted for over half of GSE business in April for the first time since August of last year. But the refinance side of the business fell again in April, to just $25.49 billion. That was down 17.8...