US Homeowners With Adjustable Mortgages Face $1,000-a-Month Jump

A small but mostly affluent group of Americans are about to see their mortgage payments skyrocket.

They are the more than 1.7 million owners of homes bought since 2019 with an adjustable-rate mortgage. These loans — averaging about $1 million to finance more expensive properties — are set at a rate lower than the prevailing 30-year for the first few years, then adjust once or twice a year based on current borrowing costs.

Coming out of the fixed period after interest rates soared to a two-decade high is the worst timing for an estimated 330,000 of these borrowers. Another 100,000 ...