US mortgage financing costs crossed a key affordability threshold this week, with the average 30-year fixed rate reaching 7.24% on September 16, 2026, according to Mortgage News Daily, before easing to 7.19% the next day. Freddie Mac’s weekly measure rose to 6.95% for the week ending September 17, from 6.76%, marking a fourth consecutive increase and the largest weekly gain in 16 months. The 15-year fixed rate climbed to 6.26% from 6.09%, compared with 5.41% a year earlier. Higher borrowing costs are weighing on demand: purchase-mortgage applications fell 19% year over year last week, while refinancing activity dropped 65%. A rise from 5.98% in late February has added about $255 to estimated monthly payments on a $400,000 loan, while housing costs reached 44% of typical household income in July. Existing-home sales fell 2% in August, pending sales rose just 0.3% from July and declined 4.7% year over year. Mortgage rates have been pressured by the 10-year Treasury yield, which breached 5% on Monday for the first time since 2023, alongside federal borrowing, corporate debt issuance linked to AI infrastructure, elevated oil prices and the Federal Reserve’s quarter-point rate increase. Economists differ on whether tighter policy will eventually support lower mortgage rates or prolong the housing slowdown, but the market currently faces weak activity from both buyers and sellers.