While falling mortgage rates will improve affordability, the "lock-in effect" for existing homeowners with ultra-low rates will persist. This will suppress the typical sales volume rebound, leading to an anemic 3% growth in purchase volumes, a historically tepid response to improved affordability conditions.

Counterintuitively, rising interest rates make mortgage servicing businesses more valuable. When rates rise, homeowners with existing low-rate mortgages are less likely to refinance or move. This provides the mortgage servicer with a longer, more predictable stream of payments, increasing the value of their servicing rights.

Trying to buy a home based on interest rate forecasts is a losing game, as predictions are consistently wrong. A better strategy is to buy when your personal finances and life circumstances are right (the "marriage") and treat the current mortgage rate as temporary (the "date"), with the option to refinance later.

The mortgage rate "lock-in effect" is more severe than a simple rate comparison suggests. For a homeowner who bought in 2016 and refinanced, selling and buying a new home today could increase their monthly mortgage payment by as much as 200%, or over $1,300.

With high interest rates freezing the existing home market, homebuilders are successfully competing by using their own margins to "buy down" mortgage rates for customers. This strategy allows them to continue selling inventory even when affordability is broadly challenged.

ARMs tempt buyers with low initial payments, but they are a gamble. You're betting that your income will rise, rates will fall, or home values will increase before your payment jumps significantly. This risk is often downplayed by lenders who are incentivized to sell loans.

The gap between existing mortgage rates (under 4.25%) and new rates (over 6.25%) is over 200 basis points. This spread, which disincentivizes homeowners from selling, has persisted for three consecutive years. Historically, the gap only exceeded 100 basis points for a total of eight quarters over the past four decades, making the current situation a major anomaly.

A common myth is that the Fed directly sets mortgage rates. In reality, lenders price 30-year mortgages off the 10-year Treasury yield, which reflects long-term market sentiment about inflation and debt. The Fed's rate is for overnight bank lending and has only an indirect influence.

New regulations like the Basel Endgame are expected to give banks more capital and regulatory clarity. This will encourage them, as the largest mortgage investors, to resume buying mortgages, tightening the 'spread' component of mortgage rates and thus lowering borrowing costs.