September 10, 2026 Mortgage–Treasury Spread: Align the Dates

Our calculation puts the September 10, 2026 mortgage–Treasury spread at about 197 basis points, essentially unchanged from the previous week, when observation windows are approximately aligned. Pairing the same weekly mortgage rates with release-day Treasury yields instead suggests a 13-basis-point narrowing. The choice of dates changes the apparent result. The calculations use Freddie Mac’s September 10 release and Treasury’s dated observations.

Information cutoff: September 10, after publication of that day’s Treasury observation.

The release covers September 3–9 applications

Freddie Mac published its Primary Mortgage Market Survey, or PMMS, at noon Eastern on September 10. The release reported a 30-year fixed mortgage rate of 6.76%, up from 6.71% a week earlier—a five-basis-point increase. One basis point equals 0.01 percentage point.

The application-based methodology introduced in November 2022 collects rates from applications submitted through Freddie Mac’s Loan Product Advisor underwriting system during the preceding Thursday–Wednesday period. This release therefore covers September 3 at 12:00 a.m. through September 9 at 11:59 p.m. Eastern. The prior release covers August 27–September 2.

Freddie Mac describes the benchmark as conventional, conforming purchase loans for borrowers with excellent credit and 20% down. It cannot establish a particular borrower’s offer or represent every loan program. Our explanation of what the PMMS benchmark measures provides that context.

Align the Treasury observations with the application window

For each application window, take the simple arithmetic mean of the published daily 10-year Treasury par yields. Give each available observation equal weight, omit days without observations, and do not carry Friday’s yield across the weekend or holiday.

The Treasury table contains no September 7 observation, leaving four observations in the second window.

Keeping the averages unrounded before subtraction gives:

• Prior window: (4.67 + 4.73 + 4.75 + 4.79 + 4.79) ÷ 5 = 4.746%. Subtracting from 6.71% gives 1.964 percentage points, or 196.4 basis points.
• Current window: (4.77 + 4.78 + 4.80 + 4.83) ÷ 4 = 4.795%. Subtracting from 6.76% gives 1.965 percentage points, or 196.5 basis points.

Mortgage rates rose five basis points while the aligned Treasury average rose 4.9 basis points. The resulting 0.1-basis-point spread increase is smaller than the reporting precision of the individual inputs. The defensible reading is essentially unchanged, rather than meaningful widening.

This convention aligns the calendar window approximately. It does not reproduce the distribution of application submissions across days or their intraday timing. This is our benchmark calculation, not a spread published by Freddie Mac.

Release-day yields create an apparent narrowing

Treasury reported 10-year yields of 4.77% for September 3 and 4.95% for September 10. Pair those yields with the PMMS figures published on the same dates and the difference falls from 194 to 181 basis points:

• September 3: (6.71 − 4.77) × 100 = 194 basis points.
• September 10: (6.76 − 4.95) × 100 = 181 basis points.

That apparent 13-basis-point narrowing combines weekly mortgage observations with single-day Treasury observations outside their respective application windows. It does not establish a comparable weekly improvement in mortgage pricing.

Publication timing adds another mismatch. Treasury’s inputs are indicative bid quotations around 3:30 p.m., and its yield data are usually available by 6 p.m. Eastern. September 10’s official daily observation was therefore unavailable when PMMS appeared at noon.

What the benchmark difference measures

The subtraction measures the distance between a borrower-rate benchmark and a government-bond yield. Mortgages repay principal over time and may repay early; a Treasury note returns principal at maturity. Mortgage-backed securities, or MBS, pass mortgage cash flows to investors. When borrowers refinance after rates fall, those investors receive principal back sooner and face lower reinvestment yields. A Boston Fed paper published May 19, 2026 explains why these cash-flow differences make the 10-year yield an imperfect mortgage reference. Aligning observation dates does not resolve them.

An MBS option-adjusted spread requires modeling

An option-adjusted spread estimates a security’s spread over a benchmark after accounting for borrowers’ prepayment option. That requires modeling beyond subtracting a Treasury yield from PMMS. A Federal Reserve staff paper’s explanation of MBS pricing distinguishes this adjustment from an unadjusted yield gap. Our 196.5-basis-point calculation supplies no estimate of September 10’s MBS option-adjusted spread.

The gap cannot identify lender profit

Even the narrower difference between borrower mortgage rates and secondary-market mortgage rates includes servicing, guarantee fees, and originators’ costs and returns, as a Dallas Fed analysis published April 4, 2023 explains. The broader Treasury comparison cannot isolate profit or show how much room a lender has to reduce a quote.

Why daily headlines can disagree with the weekly survey

When interpreting mortgage pricing coverage, check whether the reported rate is a daily quote or a weekly application average. The two can move differently because they sample different periods and borrowers. PMMS uses application submissions rather than exclusively rates locked that day, so disagreement alone does not establish an error.

For example, if rates fall on Thursday after rising during the preceding week, a daily headline can report a decline while Thursday’s PMMS still reports an increase. This is a hypothetical timing illustration, not a description of September 10’s mortgage quotes.

For market commentary, label the mortgage window, Treasury window, and averaging rule alongside the spread. For a borrower conversation, obtain a current quote with its points and lock terms before discussing negotiations. Keep the dated benchmark in mortgage-rate data and reports separate from the offer being evaluated.