The quick read: Yes. Buying at a cap rate below the mortgage rate is negative leverage at any loan size, and the real test is stricter than the coupon: leverage is negative whenever the cap rate sits below the loan constant, the year's principal and interest divided by the loan amount. Treasury's daily par yield curve shows the 10-year yield at 5.13% on October 21, 2026, and fixed coupons are built on that index plus a spread. The Federal Reserve's May 2026 Financial Stability Report says cap rates at purchase have recovered from their 2022 lows to a level just below the historical average. So test the deal before you assume debt adds return, and plan to earn the return from net operating income growth, lower leverage or interest-only payments.
What is the loan constant, and why compare it with the cap rate?
The loan constant is a year of principal and interest payments divided by the loan amount, and you compare it with the cap rate because the cap rate is what each dollar of price earns before debt while the constant is what each borrowed dollar costs in cash. When the constant is higher, borrowing lowers your cash yield.
The Federal Reserve's May 2026 Financial Stability Report describes capitalization rates at purchase as a measure of the annual income of commercial properties relative to their prices. That is the unlevered yield. The constant is the debt's cash cost, and it is only equal to the coupon on an interest-only loan. Amortization adds principal to every payment, so the constant rises above the coupon, and it rises further as the amortization period shortens:
Loan constant, interest-only at an illustrative 6.50% coupon (our arithmetic): 6.50%
Loan constant, 30-year amortization at 6.50% (our arithmetic): 7.58%
Loan constant, 25-year amortization at 6.50% (our arithmetic): 8.10%
10-year Treasury par yield, October 21, 2026 (U.S. Treasury): 5.13%
10-year Treasury par yield, October 5, 2026 (U.S. Treasury): 5.31%
The 6.50% coupon is an assumption used to show the mechanism, about 1.4 percentage points over the October 21 Treasury yield. Your own quote sets your spread. Freddie Mac's fixed-rate loan sheet (dated 4/26) calls the Treasury index the most volatile part of the coupon, which is why a move in the 10-year reaches a purchase loan quickly.
How do you test a deal for negative leverage in three numbers?
You test a purchase for negative leverage with three numbers, the cap rate on your price, the loan constant on your quote and the loan-to-value ratio, because cash-on-cash return equals the cap rate minus LTV times the constant, divided by one minus LTV. If the cap rate beats the constant, debt raises your return; if not, it lowers it.
Run it in this order:
- Cap rate. Divide in-place net operating income by the purchase price. Use the income you are buying, not the pro forma. The cap rate calculator does the division.
- Loan constant. Take the annual debt service on the quote and divide by the loan amount. Ask for the amortization period and any interest-only period in writing, because both change the constant.
- Leverage. Multiply the constant by the LTV, subtract it from the cap rate and divide by the equity share. That is your year-one cash-on-cash return before closing costs and reserves.
The same three numbers give you the debt service coverage ratio: cap rate divided by the product of LTV and the loan constant, so 6.00% ÷ (65% × 7.58%) ≈ 1.22x. Freddie Mac's fixed-rate sheet sets a minimum amortizing debt coverage ratio of 1.25x. At a 6.00% cap rate, a 6.50% coupon and 30-year amortization, a 65% loan covers only 1.22x, and the most a 1.25x test allows is about 63% of value (our arithmetic). A cap rate below the coupon shrinks the loan as well as the yield.
What does negative leverage look like on an illustrative purchase?
On an illustrative $10 million purchase at a 6.00% cap rate with a 65% loan at a 6.50% coupon and 30-year amortization, the property throws off $600,000 of income, the loan costs about $493,000 a year, and the $3.5 million of equity earns about 3.06% in cash, roughly half the 6.00% it would earn with no debt (our arithmetic).
Every figure in the table is an assumption chosen to show the mechanism. None is a quote, a market cap rate or a lender term. The deals differ only in cap rate and payment type:
| Illustrative line (our arithmetic) | Deal A | Deal B | Deal C | Deal D |
|---|---|---|---|---|
| Illustrative line (our arithmetic) Cap rate on price | Deal A 6.00% | Deal B 7.00% | Deal C 7.00% | Deal D 8.00% |
| Illustrative line (our arithmetic) Coupon | Deal A 6.50% | Deal B 6.50% | Deal C 6.50% | Deal D 6.50% |
| Illustrative line (our arithmetic) Payment type | Deal A 30-year amortization | Deal B 30-year amortization | Deal C Interest-only | Deal D 30-year amortization |
| Illustrative line (our arithmetic) Loan constant | Deal A 7.58% | Deal B 7.58% | Deal C 6.50% | Deal D 7.58% |
| Illustrative line (our arithmetic) Cash-on-cash at 65% LTV | Deal A 3.06% | Deal B 5.91% | Deal C 7.93% | Deal D 8.77% |
| Illustrative line (our arithmetic) DSCR at 65% LTV | Deal A 1.22x | Deal B 1.42x | Deal C 1.66x interest-only; 1.42x amortizing | Deal D 1.62x |
| Illustrative line (our arithmetic) Leverage | Deal A Negative | Deal B Negative | Deal C Positive | Deal D Positive |
Deal B is the trap. Its 7.00% cap rate beats the 6.50% coupon, so it looks like positive leverage on a quick read, but the 7.58% constant is higher, and the equity earns 5.91% against 7.00% unlevered. Deal C is the same building with interest-only payments, and the sign flips. Deal A fails both tests.
One refinement keeps the comparison honest. Cash-on-cash counts cash only, and the principal in an amortizing payment builds equity you get back at sale or refinance. So the constant is the test for cash yield, and the coupon is the floor for total return. A cap rate below the coupon, as in Deal A, fails on both measures.
When is negative leverage acceptable on a purchase?
Negative leverage is acceptable when the plan, not the debt, produces the return: income growth you can document, a hold short enough that the gap costs little, and cash flow that still covers debt service at closing, because a deal that needs falling rates or rising values to work is a bet on the market rather than on the property.
The income growth required is easy to size. Deal A's income must rise about 26% before its yield on the purchase price reaches the 7.58% constant; Deal B needs about 8% (our arithmetic). Ask where that growth comes from: leases rolling to market, units being renovated, expenses you can cut. If you cannot point to it, size the loan as if it will not arrive.
The failure mode has a recent record. Trepp's analysis of CRE CLO multifamily loans securitized in 2021 and 2022 in the five states with the most securitized multifamily debt (posted October 16, 2026) found the cohort's median net cash flow DSCR fell from 1.60x at securitization to 0.64x. Trepp notes the loans float over SOFR, which averaged 0.04% in 2021 and 3.66% in September 2026, and the cohort's median coupon is now 7.16%. Those were transitional loans priced for growth that had to outrun the debt.
Lenders are watching the same risk. The Federal Reserve's Beige Book of October 14, 2026 reports a New York District contact saying interest rate exposure had become the dominant question among banks and institutional investors, citing significant repricing on maturing fixed-rate loans. Boston District contacts said financing costs increased and loan terms tightened.
Negative leverage can still be the right call when:
- The business plan adds income you can underwrite line by line, such as leases already signed or below-market rents rolling over within the hold
- The hold is short and the exit does not assume a lower cap rate than the one you bought at
- Year-one cash flow covers debt service at the lender's minimum without drawing reserves
- The rate is fixed, or a floating rate is capped at a level the plan can carry
How do lower leverage or interest-only change cash-on-cash?
Lower leverage shrinks the damage from negative leverage but never reverses it, while interest-only payments can reverse it, because interest-only drops the loan constant to the coupon, and a cap rate between the coupon and the amortizing constant turns from negative leverage to positive the moment principal comes out of the payment.
At Deal A's numbers, cutting the loan from 65% to 50% of value lifts cash-on-cash from 3.06% to about 4.42%, still below the 6.00% unlevered yield. Interest-only on Deal A gets to about 5.07%, also below 6.00%, because the cap rate is under the coupon itself. On Deal B, interest-only lifts cash-on-cash from 5.91% to 7.93% (all our arithmetic). The lesson: when the cap rate is below the coupon, less debt is the only lever that helps, and it helps by reducing the drag rather than by adding return.
Interest-only does not buy more proceeds. Freddie Mac's fixed-rate sheet computes the debt coverage ratio for interest-only periods on an amortizing payment, and it caps full-term interest-only loans at 65% of value for terms of five to seven years and 70% for terms over seven years, against 75% to 80% for amortizing loans. Expect a lender to size your loan as if it amortizes even when the payment does not.
How do you get an acquisition loan placed when the cap rate is below the mortgage rate?
You get an acquisition loan placed by showing each lender the same three numbers you used to test it, the cap rate, the loan constant you can carry and the leverage that clears its coverage minimum, with the income plan that closes the gap. YieldStack is an AI-native commercial mortgage brokerage that arranges financing for commercial real estate investors.
Three routes are common. YieldStack publishes this guide and lists its own service first as our recommendation, for these reasons:
1. A commercial mortgage brokerage: YieldStack (our recommendation). YieldStack's software matches the deal against a catalog of 20,000+ loan programs, so you can compare amortization, interest-only and leverage across lender types instead of taking one structure. Human brokers then structure the request, negotiate for the borrower and carry the deal toward closing. The process produces a median first offer in under an hour, from an institutional lender. Every credit decision is made by the lender; YieldStack arranges the introductions and negotiates on the borrower's side, and no loan, rate, or closing is guaranteed.
2. Going direct to one lender. You get one lender's structure, one view of amortization and one coverage test. That works when you already know the structure you need.
3. Your relationship bank. Useful for speed on a deal the bank already understands, but its amortization and recourse terms may not match the cash-on-cash you modeled.
What to send:
- Trailing 12-month operating statement and current rent roll, so the lender sees in-place income
- Purchase contract and the price that sets your cap rate
- Your business plan with the dated sources of income growth
- Target loan amount, the amortization and interest-only period you need, and the leverage you can accept
- Hold period, exit assumption and the prepayment flexibility you need
The acquisition loan page covers the loan types, and the deal analyzer runs the full return on your numbers. When the package is ready, send the deal for review. It costs Zero upfront to submit a deal and review offers; YieldStack's broker fee is 0.50–1.00% of the loan amount and is paid only at closing.
The bottom line
A cap rate below the mortgage rate is always negative leverage, and a cap rate below the loan constant is negative leverage for cash yield even when it beats the coupon. With the 10-year at 5.13% on October 21, 2026, run the three-number test on every purchase, then decide whether income growth, lower leverage or interest-only earns the return the debt will not.