Mortgage lenders that sell loans to Fannie Mae and Freddie Mac opened the credit box slightly for refinance borrowers during the second quarter, according to a new Inside Mortgage Trends analysis of mortgage-backed securities data. Some 24.8 percent of refinance loans securitized by the two government-sponsored enterprises during the second quarter had credit scores below 700. That was up from 22.6 percent in the previous period and just ... [Includes two data charts]