A 30-year fixed mortgage rate is the 10-year Treasury yield plus a spread, and both halves move on their own. Bond investors set the 10-year every trading day. The mortgage-bond market and lender capacity set the spread. The Federal Reserve sets neither. It sets an overnight rate that banks charge each other, eight times a year. That's why the Fed can cut and your rate can rise, as it did in late 2024. Here's the machinery, every number dated.
What is the 10-year Treasury yield, and why does its price move opposite its yield?
A 10-year Treasury note is a loan to the U.S. government. The rate gets fixed at auction, paid every six months, and never changes. Treasury offered $42 billion of them at the August 12, 2026 auction. After the auction the note trades every day, and that's where the yield comes from: the coupon is locked, so the only thing that can change is the price, and a lower price on the same coupon means a higher return.
An illustrative example, not an offer or a rate/APR quote: a $1,000 note pays 4%, or $40 a year. If buyers need 5% to lend the government money for ten years, they pay about $923. If 3% is enough, they pay about $1,085. Same note, same $40; the price fell, so the yield rose.
The yield you hear about in the news is the Fed's H.15 figure, FRED series DGS10: 4.96% on September 21, 2026, up from a low of 3.97% on February 27 and just off the 5.01% it touched on September 16 and September 18. That's just under a full point in seven months, and the Fed didn't move until September 16.
What makes the 10-year Treasury yield go up?
A ten-year yield is three things. The real yield is what investors earn above inflation, read off 10-year Treasury Inflation-Protected Securities (FRED series DFII10). Expected inflation is the breakeven rate (T10YIE), the plain 10-year minus the TIPS yield. The term premium is the extra yield investors demand for locking money up for ten years instead of rolling short-term bills. It's an estimate, and the Fed Board publishes one.
How inflation reaches your mortgage rate covers the inflation leg. Here's what surprised me when I ran the numbers.
From the February 27 low to September 21, 2026, the 10-year rose 0.99 points. The breakeven barely moved: 2.25% to 2.34%. The real yield did the work: 1.72% to 2.62%. The Fed Board's term-premium estimate roughly doubled, from 0.46% to 0.96%. So the bond market didn't raise its ten-year inflation forecast this year. It repriced the real cost of ten-year money.
What pushes those pieces around: inflation reports (the August 2026 CPI, released September 11, ran 3.4% over the year), the jobs report, Treasury supply (the next refunding announcement is November 4, 2026), the Fed's balance sheet, foreign and bank demand, and fear, which sends investors into Treasuries and pushes yields down.
What does the Fed actually set?
An overnight rate, and that's it. In the Fed's words, "the interest rate at which depository institutions lend reserve balances to other depository institutions overnight." The Federal Open Market Committee sets a target range for it at eight scheduled meetings a year.
On September 16, 2026 the committee raised that range a quarter point to 3.75% to 4.00%, effective September 17, the first increase since July 2023. The effective rate settled at 3.88% on September 21. The next scheduled meeting is October 27-28, 2026.
The Fed doesn't set the 10-year or the spread. It has influence, through the expected path of that overnight rate, what it says, and its balance sheet. The short end of the curve listens closely, the long end loosely. From August 20 to September 21, 2026, the 2-year Treasury rose 0.57 points, from 4.19% to 4.76%, while the 10-year rose 0.27, from 4.69% to 4.96%. The Dallas Fed's May 2026 number: mortgage rates move with a beta below 20% to the fed funds rate and about 85% to the 10-year.
I wrote the short version in Do mortgage rates follow the Fed?: the bond market votes daily, the Fed eight times a year, and by then the 10-year has usually priced the result.
Why can mortgage rates rise after the Fed cuts?
Because the cut hits the overnight rate, and your mortgage rate hangs off the ten-year one. Late 2024 is the cleanest example, all from FRED.
| Series (FRED id) | Sept 18, 2024 | Dec 26, 2024 | Change (points) |
|---|---|---|---|
| Fed funds target range (DFEDTARU/L) | 5.25% to 5.50% | 4.25% to 4.50% | -1.00 |
| 10-year Treasury (DGS10) | 3.70% | 4.58% | +0.88 |
| Real yield (DFII10) | 1.58% | 2.23% | +0.65 |
| Breakeven inflation (T10YIE) | 2.12% | 2.35% | +0.23 |
| Fed Board term-premium estimate (THREEFYTP10) | 0.09% | 0.70% | +0.61 |
| Freddie Mac 30-year average (MORTGAGE30US) | 6.09% (Sept 19) | 6.85% | +0.76 |
| Spread on the survey date (Sept 19 10-year: 3.73%) | 2.36 | 2.27 | -0.09 |
The Fed cut a full point across September 18, November 7, and December 18, 2024, and the 30-year fixed rose three-quarters of a point. All of that rise came from the 10-year leg; the spread narrowed. As of May 2026 the funds rate sat 175 basis points below its mid-September 2024 level and, the Dallas Fed noted, mortgage rates were little changed on net. The September 2026 Fed meeting piece covers lock decisions around a meeting.
What is the mortgage spread over the 10-year, and why does it exist?
The spread is the Freddie Mac 30-year average minus the 10-year Treasury yield on the same day. The Richmond Fed uses that definition and warns it's a poor gauge of financial stress, since much of its movement comes from refinancing behavior.
Why the 10-year and not the 30-year Treasury? Because a 30-year mortgage almost never lasts thirty years. People refinance, move, and pay off early. The Dallas Fed puts the Treasury maturity that best matches a mortgage at seven to ten years, before prepayments shorten it further.
Fannie Mae splits the spread into the lender's layer (servicing, agency fees, origination, profit; about 1.01 points since 2008) and the investor's layer, mainly prepayment risk, which averaged 0.71 points from 2012 through 2019 and 1.4 from January 2022 through November 2024.
Prepayment risk is the piece that swings. Your mortgage comes with an option to refinance whenever rates drop, and the Dallas Fed describes the spread as including "the investor's compensation for selling the borrower the option to refinance." When rates fall, everyone refinances and the investor gets the money back at the worst time. When rates rise, nobody refinances and the investor is stuck holding the old coupon. The Philadelphia Fed's phrase: "the duration of MBS is not fixed." The Freddie Mac number itself is a Thursday survey average, a benchmark rather than a quote.
Why did the spread blow out in 2022 to 2024, and where does it sit now?
Four moments, Freddie Mac 30-year minus the 10-year on the survey date, from FRED:
| Moment | Date | 10-year (DGS10) | Freddie Mac 30-year (MORTGAGE30US) | Spread (points) |
|---|---|---|---|---|
| Pre-pandemic baseline | June 27, 2019 | 2.01% | 3.73% | 1.72 |
| The record low | Jan. 7, 2021 | 1.08% | 2.65% | 1.57 |
| The 2023 peak week | June 1, 2023 | 3.61% | 6.79% | 3.18 |
| Latest | Sept. 17, 2026 | 4.94% | 6.95% | 2.01 |
The spread averaged 1.69 points from 2010 through 2019, 2.58 from 2022 through 2024, and 1.91 across 2009 through 2025. The first eight months of 2026 averaged 1.96. So 2026 sits near the long-run middle, a full point below the 2023 peak.
Three dated things widened it.
The Fed stopped buying. The Fed ended mortgage-bond purchases in March 2022 and began runoff that June. Its holdings peaked near $2.73 trillion in April 2022 and stood at about $1.91 trillion in September 2026, down roughly $812 billion, or 30%. Runoff formally ended December 1, 2025, but the principal now gets reinvested into Treasury bills, so the Fed's share keeps shrinking.
Rates got volatile and the curve inverted. That refinance option costs investors more when rates swing hard, and the Urban Institute tied the 2022 widening to policy uncertainty that "resulted in large movements in interest rates." The Richmond Fed adds that an inverted curve makes households expect to refinance quickly, pushing mortgage rates up relative to the 10-year.
Banks pulled back. Bank holdings of mortgage bonds fell from near $2.99 trillion in February 2022 to about $2.49 trillion by October 2023, down 17%, with the March 2023 bank failures inside that window (that's my read, not a Fed finding). They were back to about $2.74 trillion by August 2026, part of why the spread has come in.
Both legs move, and 2026 shows it inside one year:
| Moment | Date | 10-year (DGS10) | Freddie Mac 30-year (MORTGAGE30US) | Spread (points) |
|---|---|---|---|---|
| The 2026 low | Feb. 26, 2026 | 4.02% | 5.98% | 1.96 |
| Mid-July | July 16, 2026 | 4.57% | 6.55% | 1.98 |
| Week before the hike | Sept. 10, 2026 | 4.95% | 6.76% | 1.81 |
| Latest | Sept. 17, 2026 | 4.94% | 6.95% | 2.01 |
From February to September the 10-year rose 0.92 and the spread barely changed. Now look at the last two rows: the 10-year sat still, 4.95% to 4.94%, while the spread went from 1.81 to 2.01. That's the spread moving on its own.
What do I actually watch, and why is a Fed meeting day not a rate strategy?
Every morning I check the 10-year on FRED, the mortgage-bond market, and Freddie Mac's Thursday survey. Right after this publishes, the dates that can move your rate are the Fed meeting (October 27-28), the September PCE (October 29), the Treasury refunding (November 4), the October jobs report (November 6), and the October CPI (November 10). The meeting is a volatility event. The bond market was deciding your rate every trading day before it.
One honest exception: an adjustable-rate mortgage past its fixed period, or a HELOC, is an index plus a margin, and the CFPB's HELOC guide names the U.S. prime rate and the Constant Maturity Treasury as common indexes. Prime was 7.00% on September 21, 2026, three points above the top of the Fed's range. If that's you, watching the Fed is the right call.
Here's what an eighth is worth, as an illustrative example and not an offer or a rate/APR quote. On a $400,000 30-year fixed loan, principal and interest at 6.75% is about $2,594 a month; at 6.875% it's about $2,628. That eighth is $33 a month, roughly $12,000 over 30 years; a quarter point is about $67 a month, roughly $24,000. A quarter point on either leg produces the same payment. Decide the payment that works, get your file lock-ready, and let the 10-year pick the day. I can't predict it, and nobody credible can. What I can do is watch it against a number you've already chosen. Run your own numbers on the mortgage calculators; the glossary has the terms.
FAQ
Does the Fed set mortgage rates? No. It sets a target range for the overnight federal funds rate. A 30-year fixed rate is the 10-year Treasury yield plus a spread, and the Fed sets neither.
Why does the 30-year mortgage follow the 10-year Treasury and not the 30-year Treasury? Because mortgages get paid off early. Refinancing and moving shorten a pool's life to something closer to a 10-year bond.
What is a normal mortgage spread? Roughly 1.5 to 2.5 percentage points over the 10-year. The average was 1.69 from 2010 through 2019 and 1.91 across 2009 through 2025, including the 2022-2024 blowout; the peak was 3.18 in the first week of June 2023.
Tell Me Your Number and I Will Watch the Bond Market
Math is what I do, so you don't have to read the Treasury market. Send me your loan amount, your current rate if you have one, and the monthly payment that works, and I'll tell you what the 10-year and the spread have to do to get you there. Then I'll watch them for it. No obligation. Call or text (949) 990-6030, or schedule a call. Knowledge is power.
