When the Federal Reserve holds rates steady, many ARM borrowers assume their mortgage payments will stay flat too. That assumption is wrong and can lead to unexpected payment increases. Adjustable-rate mortgages reset based on specific market indexes, not directly on the Fed’s policy rate, and those indexes can move independently. Even during a period of stable Fed policy in summer 2026, ARM holders face real risks if they misunderstand how their loan adjusts.

ARMs Do Not Track the Federal Funds Rate Directly

The Federal Reserve sets the federal funds rate, which influences but does not dictate the indexes that drive ARM adjustments. According to the Consumer Financial Protection Bureau, most ARMs adjust based on the Secured Overnight Financing Rate (SOFR), the one-year Constant Maturity Treasury (CMT), or another benchmark published by financial markets (CFPB, 2024).

When the Fed holds its policy rate steady, SOFR and other indexes can still rise or fall based on credit conditions, Treasury yields, and demand for short-term funding. A flat Fed rate in summer does not lock your ARM rate in place. If your loan’s index rises between now and your next adjustment date, your rate and payment will increase, regardless of what the Fed does.

Summer Timing Often Coincides With Adjustment Periods

Many ARMs originated in late spring or early summer, meaning their annual or semi-annual adjustment dates fall in June, July, or August. If you took out a 5/1 ARM in summer 2021, your initial fixed period ended in summer 2026, and your first adjustment happens now. The Federal Reserve’s interest rate data shows that short-term rates have fluctuated throughout 2025 and early 2026, even as the Fed paused its rate moves (Federal Reserve, 2024).

Borrowers who have not reviewed their loan documents in years may be surprised by how much their rate can change at the first adjustment. The initial rate on many ARMs was a discounted teaser rate, well below the fully indexed rate, so the jump can be significant even if the index itself has not moved much.

Rate Caps Limit but Do Not Eliminate Risk

ARMs include rate caps that restrict how much your rate can increase at each adjustment and over the life of the loan. A typical structure is 2/2/5, which means the rate can rise by up to 2 percentage points at the first adjustment, up to 2 points at each subsequent adjustment, and up to 5 points total over the loan’s life.

Those caps are protective, but they still allow for large payment increases. If your initial rate was 3.5 percent and the first adjustment cap is 2 points, your new rate could jump to 5.5 percent. On a $400,000 loan, that would increase your principal and interest payment by roughly $460 per month. The cap prevented an even larger increase, but the payment shock is real.

What You Should Do Before Your Next Adjustment

Check your loan documents to identify your ARM’s index, margin, adjustment date, and caps. Your loan servicer is required to send you a notice before each adjustment, typically 60 to 120 days in advance, but you should not wait for that notice to start planning.

Read also: Adjustable-Rate Mortgage Risks in the US When the Fed Holds Rates Steady in Summer

Look up the current value of your index. SOFR and CMT rates are published daily by the Federal Reserve and financial data providers. Add your loan’s margin (a fixed percentage stated in your documents) to the current index value to estimate your new fully indexed rate, then apply your caps to see the maximum rate you could face.

If the projected rate and payment are higher than you can comfortably afford, consider refinancing into a fixed-rate mortgage before your adjustment date. Refinancing makes sense if you plan to stay in the home for several more years and current fixed rates are competitive with or below your projected ARM rate. As of July 2026, rates change daily, so verify current terms with a licensed lender before deciding (Fannie Mae, 2024).

You may also choose to stay in the ARM if you plan to sell or refinance within the next year or two and believe rates will fall in that window. That is a judgment call based on your financial situation, timeline, and risk tolerance, not general advice.

The Bottom Line

A stable Fed rate does not mean stable ARM payments. Your loan adjusts based on a specific market index that moves independently of Fed policy. Summer is a common adjustment season for many ARMs, and even with rate caps in place, payment increases can be substantial. Review your loan terms now, estimate your next rate, and decide whether refinancing or staying in the ARM is the better move for your personal situation. Always confirm current rates and eligibility with a licensed loan officer, as loan terms, limits, and availability vary by program, lender, and location.

Financial Disclaimer: This article provides general educational information about adjustable-rate mortgages and is not personalized financial, lending, or legal advice. Mortgage rates, loan eligibility, and program availability vary by lender, borrower qualifications, and location. Interest rates change daily. Consult a licensed mortgage professional or HUD-approved housing counselor to discuss your specific situation before making any financing decisions.