WASHINGTON >> Mortgage rates fell for the fourth straight week, undercut by worries that the surging delta coronavirus variant and the worsening pandemic in hotspots around the world could derail what has been a strong economic recovery.

Mortgage buyer Freddie Mac reported today that the average for the 30-year home loan dipped to 2.78% from 2.88% last week, down from its peak this year of 3.18% in April. The key rate stood at 3.01% a year ago.

The rate for a 15-year loan, a popular option among homeowners refinancing their mortgages, declined to 2.12% from 2.22% last week.

The concern over the pandemic’s potential effects on the recovery spurred a rout in global markets on Monday, with the Dow Jones Industrial Average falling 2.1%. Stocks of companies that would be hurt the most by potential COVID-19 restrictions sustained some of the heaviest losses. Financial markets have been showing signs of increased concern for a while, but the U.S. stock market had remained largely resilient.

Many would-be homebuyers haven’t been able to take advantage of the ultra-low mortgage rates because of the tight supply of homes for sale and high prices. The National Association of Realtors reported today that sales of previously occupied homes rose in June, snapping a four-month losing streak, while strong demand for higher-end properties and low home-loan rates helped push prices to new highs.

The government reported today that the number of Americans seeking unemployment benefits rose last week from the lowest point of the pandemic, even as the job market appears to be rebounding on the strength of a reopened economy. Jobless claims increased to 419,000, the most in two months, from 368,000 the previous week.