Mortgage‑and‑Gain Lock‑In

Home owners are 'locked in' when legacy below‑market mortgages and large unrealized capital gains make selling or moving financially punitive. That combined effect reduces listings, depresses transaction volumes, and pushes prices up because sellers rationally refuse to list at prevailing market terms. — Framing housing constraints as a lock‑in problem reframes policy from demand stimulation to targeted supply unblocking (mortgage portability, capital‑gains indexing/deferral), changing where federal intervention is likely to be effective.