A trend of fewer homeowners refinancing their mortgages as interest rates climb is helping to curb sales of home-loan bonds without government backing. It’s also making new notes being issued safer, according to Moody’s Investors Service.

Mortgages used to buy homes historically default less than replacement loans, partly because of the greater vigor employed by lenders in underwriting the first category of debt, the New York-based ratings firm said Wednesday in a report. The dynamic is beneficial for investors as higher rates reduce how many consumers can benefit by refinancing, boosting the share of purchase loans in pools backing non-agency bonds, Moody’s said.