The buydown transfers mark-to-market risk from builder’s income statements onto the balance sheets of the buyers who took the subsidized deals, and selectively. A buyer whose 6.65% payment would exceed the DTI threshold can instead qualify at the bought-down 4.9%. The subsidy does not change the preferences of infra-marginal buyers; it changes who can close. This buyer, however, is the one with the least equity cushion, the least refinance flexibility, and the least room to absorb a later shock, such as tax reassessments, insurance repricing (sharpest in Florida, Texas, and Arizona), and dues from homeowners associations.
The risk does not need a downturn to bite; it is priced in at closing. The recorded price and every comp built on it read $426,000, but the price a resale buyer can finance at 6.65%, with no buydown available to them, is closer to the $371,000 the builder netted. That gap is not the home’s value collapsing; it is the distance between the inflated recorded price and the resale-clearing price. The owner does not feel it while living in the house because the rate buy-down delivers an ongoing below-market payment. They feel it on exit.
Trace the exit for the marginal buyer the subsidy pulls in, with the market unchanged. They buy at the recorded $426,000 with 10% down: $42,600 in cash, and the remaining $383,400 is financed. The resale clears at the $371,000, the builder’s true realized net revenue. After roughly 6% ($22,260) a sale carries in commissions and closing costs, that yields $348,740, which is $34,660 short of the loan. The seller must write a check for that $34,660 just to clear the mortgage, and gets none of the $42,600 back. The seller walks away about $77,260 poorer ($42,600 down payment plus $12,400 loan gap plus $22,600 closing cost), without a single point of price decline. Even at the Federal Housing Administration (FHA) minimum 3.5% down the loss is $77,260; the difference is the seller now needs to bring $62,350 to the closing. Refinancing offers no escape in either rate environment. The buyer is locked in.
This phenomenon is most visible in the Sunbelt metro area, where we see the most buy-down-driven volume, and where valuations were already stretched, as noted in Zillow ZHVI and Census income data. Austin sits at 5.13x price-to-income, 32% above its pre-2020 norm of 3.90x; Phoenix (4.56x) and Tampa (4.53x) run 30% to 42% above the 3.2 to 3.5x national baseline. A buyer entering at an inflated price there carries the exit risk on top of a high valuation. Builders hold reported margins and equity valuations by pushing that risk onto the households least able to absorb it.
