The lock-in effect, explained
A buyer looks at a triple-decker in Worcester, does the math on today’s rate, and offers under asking — expecting the seller to feel pressure to deal. Instead, the seller shrugs and re-lists at the same number. That reaction isn’t stubbornness. It’s the lock-in effect, and it’s the single biggest reason Massachusetts inventory has stayed thin since 2022.
The gap that changed everything
Roughly two-thirds of Massachusetts owners financed or refinanced near 2021’s 3% low. Rates have since climbed to about 6.76% — a 3.8-point gap with real teeth: trade a $500,000 mortgage at 3% for the same loan today and the monthly payment jumps over $1,100, a 54% increase for the identical property. Selling doesn’t just mean giving up a home; it means giving up that rate everywhere else, too.
There’s no empty-nest moment to force a sale
It also matters that these are investment properties, not primary homes. A homeowner eventually sells because life changes — kids move out, a job relocates, retirement calls for less space. A triple-decker or six-unit has no such moment. If the property is cash-flowing — rents covering the mortgage, taxes, and upkeep with room left over — there is no personal milestone pushing an owner toward the market. The only question is whether the numbers still work, and a 3% note makes sure they do.
A market that was already mature
Rate lock-in also lands differently here than in a fast-growing Sunbelt metro. The median multifamily property in our Boston, Worcester, and Somerville sample was built around 1900 — in line with the state as a whole, where the median sale across all Massachusetts multifamily transactions is a 1903-built property, and nearly 92% predates 1950. There’s little vacant land left to build on and few new triple-deckers coming online to replace the ones that don’t sell. In a market this mature, low turnover doesn’t get diluted by new supply the way it would in a region still being built out — it just compounds.
Owners are choosing not to sell
The result shows up directly in the deed records. Sales volume in Boston, Worcester, and Somerville all peaked in 2021 and fell 25–45% by 2023, even as the region’s population and rental demand kept growing. Owners who don’t have to move simply aren’t moving — fewer listings, not less demand.
The ones who do sell aren’t discounting
This is the part that surprises buyers most: thinner inventory hasn’t translated into price cuts. Across all three cities, sale prices have held at or above asking in every year since the rate shock began. Sellers who list have already decided the move is worth it — they are not first-time sellers testing the water, so they hold firm.
What this means for negotiating room
For buyers, the practical read is this: don’t expect rate-driven leverage on price. The leverage that does exist shows up elsewhere — longer inspection periods, credits toward rate buydowns, or flexible closing timelines — because the seller who’s listing at all has already cleared the hardest hurdle: giving up their 3%.