September Multifamily Mortgage Rates Based on the 10 yr T-Bill

Mortgage rates, especially fixed 30-year mortgages, are closely based on the 10-year Treasury rate with different spreads depending on economic conditions and investor attitudes at the time.  Generally, mortgage rates move in tandem with changes in the 10-year T-Bill rate because both compete for similar investors in the bond market. As the 10-year Treasury yield changes, lenders adjust mortgage rates to maintain an attractive spread for borrowers versus Treasury-backed securities.

The key points to understanding this translation are:

1.      Mortgage rates are usually higher than the 10-year Treasury yields by a margin or spread of roughly 1.5% to 2.25%. This spread reflects additional risks such as mortgage prepayment and default risks that Treasury securities do not carry.

2.      If the 10-year Treasury yield rises, mortgage rates tend to increase sometimes along with the spread. If the yield falls so do mortgage rates.

3.      Rates are based on investor expectations for inflation, economic growth, and demand for mortgage-backed securities in the secondary mortgage market. Rising inflation or economic uncertainty can widen the spread, making mortgage rates rise more rapidly than the Treasury yield increases.

4.      Adjustable-rate mortgages (ARMs), and other short-term rates are more influenced by the Federal Funds Rate and LIBOR benchmarks.

Translating changes in the 10-year T-bill rate into longer term mortgage rates typically involves adding the usual market spread to the 10-year yield movement. To estimate how changes in the 10-year Treasury bill rate will impact mortgage rates for September and October 2025, follow the changes in the 10-year yield and add a spread of about 1.5% to 2.25% for fixed-rate mortgages. This provides a practical rule of thumb for understanding expected mortgage rate shifts related to Treasury yield trends.

What Should You Do Now?

The 10 yr T-Bill rate as of late August 2025 is approximately 4.22%, slightly down from recent highs around 4.3%-4.5% seen earlier in the month.  One year ago, it was approximately 3.84%.  The long-term average however is about 5.83%.   For September and October 2025, market expectations and continued stability indicate a modestly stable or slightly declining trend in the 10-year rate. Of course, significant changes in indicators like inflation, Federal Reserve policy moves, or geopolitical events can move the 10 yr up or down depending on investor expectations.  Investors looking for stability and controlled inflation currently point to a cautious but stable environment.  It seems 10 yr T-Bill rates should hover around the 4.2-4.3% range.   If you believe rates will return to historical plateaus, you would be looking at a 10 yr rate around 5.86% with long term mortgage rates around 7.11-8.11%. This may be why real estate investors and developers are trying to refinance or develop their properties now.  

Current Multifamily Mortgage Rates for September 2025

Conventional Loan Rates:     5.70% - 9.75%                   USDA Rates :        6.15% - 10.40%

Private Banking Rates:           5.60% - 10.00%                Insurance Rates :    5.35% - 8.00%

CMBS Rates :                          5.85% - 7.75%             Bridge Rates :          7.00% - 14.00%

Fannie Mae DUS Rates :        5.40% - 6.35%                  FHA Ins. Rates :      4.85% - 6.20%

Freddie Standard Rates: 5.75% - 7.40%                  Freddie SBL Rates: 5.75% - 9.20%

Construction Rates :               6.30% - 10.00%                Mezzanine Rates : 7.25% - 12.25%