Key takeaways
- The Federal Reserve does not set mortgage rates directly — it sets the overnight federal funds rate.
- Thirty-year mortgage rates track the 10-year Treasury yield plus a spread.
- That spread widens with volatility, prepayment risk, and reduced MBS demand.
- Your individual rate is the market rate adjusted for credit score, LTV, property type, and points.
From Treasuries to your rate sheet
Most conforming mortgages are pooled into mortgage-backed securities and sold to investors. Those investors price MBS relative to Treasury securities of similar expected duration — usually the 10-year note, because the average 30-year mortgage is repaid in roughly a decade through sale or refinance.
So the base rate is the 10-year Treasury yield plus a spread that compensates investors for prepayment risk and credit risk. Add servicing costs and lender margin and you get the rate sheet. The Fed influences this chain through expectations and through its own balance sheet holdings, but it does not set the number.
Why the spread moves
The MBS-Treasury spread is not constant. It widens when interest rate volatility rises, because prepayment behavior becomes harder to model and investors demand more compensation. It widens when a large buyer steps back from the market. It narrows when volatility falls and demand is deep.
This is why mortgage rates sometimes fail to fall when Treasury yields do. In periods of elevated volatility, spreads have run well above their long-run average, adding meaningfully to borrower costs independent of any Fed decision.
What determines your rate specifically
The market rate is a starting point. Loan-level price adjustments then modify it for credit score, loan-to-value, occupancy, property type, loan purpose, and loan amount. Investment property and cash-out refinances price worse. Condominiums above certain LTVs price worse. Manufactured homes price worse.
You also choose where to sit on the rate-versus-cost curve. Paying discount points buys a lower rate; taking a lender credit raises the rate and reduces cash needed at closing. Neither is inherently better — it depends entirely on how long you keep the loan. Model it in our loan comparison calculator.
Locking
A rate lock fixes your rate for a defined period, commonly 30 to 60 days. Longer locks cost more. If your lock expires before closing you pay an extension fee or take current market pricing, whichever the lender's policy dictates.
Some lenders offer a float-down option allowing a one-time reset if rates fall materially during the lock. It usually carries a cost. Ask about lock policy, extension pricing, and float-down terms before choosing a lender, not after.
Frequently asked questions
Does the Fed cutting rates lower my mortgage rate?
Not mechanically. Fed cuts move short-term rates and can move long-term yields through expectations, but mortgage rates frequently move before, against, or independently of Fed decisions.
Should I buy points?
Only if you will hold the loan past the break-even, typically four to seven years. Calculate it explicitly rather than accepting a lender's framing.
Why did two lenders quote me different rates on the same day?
Different margins, different investor relationships, different overlays, and different assumptions about points and credits. Compare Loan Estimates, not verbal quotes.
Sources & further reading
- Federal Reserve Bank of St. Louis (FRED), 10-Year Treasury Constant Maturity
- Freddie Mac Primary Mortgage Market Survey methodology
- Urban Institute Housing Finance Policy Center chartbook
Figures and rules change. Verify current requirements with the issuing agency or a licensed professional before acting.