ARREST SENDS stock market reeling before a rebound.

WASHINGTON — U.S. long-term mortgage rates fell this week amid a steep decline in stock prices.

Continued slides in the stock market and tumbling oil prices have been pushing mortgage rates lower, although home borrowing rates remain much higher than a year ago. Mortgage giant Freddie Mac — the Federal Home Loan Mortgage Corp. — said Thursday that the average rate on the benchmark 30-year, fixed-rate mortgage dipped to 4.75 percent from 4.81 percent last week. The key rate stood at 3.94 percent a year ago.

The rate on 15-year fixed-rate loans declined to 4.21 percent from 4.25 percent the previous week. The average rate for five-year adjustable-rate mortgages fell to 4.07 percent from 4.12 percent last week. The fee remained at 0.3 point.

The fall in mortgage rates “is a welcome relief to prospective homebuyers who have recently experienced rising rates and rising home prices,” Freddie Mac chief economist Sam Khater said.

Thursday’s broad decline came as news of the arrest of a senior Chinese technology executive overshadowed some positive comments on trade from Beijing, threatening to worsen U.S.-China trade tensions.

With stocks sliding, traders continued to channel money into bonds — a signal that they see weakness in the economy ahead. The yield on the key 10-year Treasury note, which tends to influence mortgage rates, dropped to 2.86 percent Thursday morning from 2.92 percent on Tuesday as bond prices rose.

To calculate average mortgage rates, Freddie Mac surveys lenders across the country between Monday and Wednesday each week.