1. What is an Interest Rate Cap?
An interest rate cap is a financial contract that protects floating-rate borrowers against rising interest rates. Think of it as an insurance policy on your interest rate — if rates rise above a specified level (the “strike”), the cap provider pays you the difference. Caps are written on SOFR (Secured Overnight Financing Rate), the benchmark that replaced LIBOR as the standard reference rate for floating-rate commercial real estate loans.
Three key terms define every cap:
- Notional Amount — The loan balance the cap covers. This is typically equal to your outstanding loan amount.
- Term — How long the cap lasts, usually matching your loan term (e.g., 2 or 3 years).
- Strike Rate — The rate ceiling. If SOFR rises above this level, the cap pays out.
How it works in practice:
You pay a one-time upfront premium to purchase the cap. If 1-Month Term SOFR stays below your strike rate, the cap costs you nothing beyond the initial premium. If SOFR rises above your strike, the cap provider reimburses you for the difference each month.
For example, if you own a $25 million floating-rate loan with a 4.00% strike cap and SOFR rises to 5.00%, the cap provider pays you the 1.00% difference on your notional — roughly $20,833 per month.
Why borrowers use caps:
- Lenders on floating-rate loans (especially agency and debt fund lenders) often require caps as a condition of closing
- Caps let you float lower when rates drop while capping your worst-case rate
- Unlike swaps, which can have a negative termination value (meaning you owe money to exit), a cap's value can only be positive or zero — you can sell it back at market value at any time without owing a termination payment
- The upfront premium is a known, fixed cost with no ongoing obligations
Replacement caps:
If your loan term is longer than your cap term, you'll need to purchase a replacement cap before the original expires. For example, a 5-year loan with a 3-year cap means you'll need a new cap in place before the end of year 3 to remain in compliance with your lender's hedging requirements. Replacement cap pricing will reflect market conditions at that future date — which may be higher or lower than today.
2. How Do Cap Payouts Work?
Once you purchase a cap, you receive payments automatically whenever the reference rate (1-Month Term SOFR) exceeds your strike rate on a reset date.
The payout formula:
Payout = Notional × max(SOFR − Strike, 0) × (Days in Period / 360)
If SOFR is at or below the strike, the payout is zero — the cap is “out of the money” for that period.
Example:
You receive this payment at the end of the accrual period, offsetting the additional interest expense on your loan above the strike.
Settlement:
Depending on your lender, cap payouts are handled one of two ways:
- Net settlement — The cap payment is netted against your loan interest, so you simply pay less interest that month
- Gross settlement — You pay full loan interest to the lender, and the cap provider sends you a separate reimbursement
In the money vs. out of the money:
- In the money (ITM) — SOFR is above your strike. The cap is actively paying out. Most of the cap's value is “intrinsic” — the payouts the forward curve already implies.
- Out of the money (OTM) — SOFR is below your strike. No payouts currently, but the cap still has value because rates could rise in the future. This remaining value is called “time value” or “option value.”
- At the money (ATM) — SOFR is right at your strike level. This is where the cap has the most time value and is most sensitive to changes in volatility.
3. What Drives Cap Pricing?
Cap pricing is driven by four primary factors: interest rate expectations, volatility, time, and liquidity. Premiums are typically quoted in dollars but can also be expressed as basis points of notional (e.g., a $150,000 premium on a $25 million cap is 60 bps upfront).
Interest Rate Expectations (Forward Curve)
The forward curve represents the market's consensus on where SOFR will be in the future. If markets expect rates to stay elevated, caps cost more because they're more likely to pay out. If rates are expected to decline, caps become cheaper.
This is why a 4.00% strike cap is more expensive when the forward curve shows SOFR at 4.50% for the next two years versus 3.50%. The higher the expected rate relative to your strike, the more “intrinsic value” the cap has — meaning the market already expects it to pay out.
Volatility
Volatility measures how much rates are expected to move. Higher volatility means more uncertainty, which makes caps more expensive — just like car insurance costs more for riskier drivers.
Even if the forward curve shows SOFR settling well below your strike, elevated volatility means there's a greater chance rates could spike above it. Cap sellers charge more to compensate for that risk. This is why caps can become significantly more expensive during periods of market uncertainty (geopolitical events, Fed policy shifts, economic data surprises) even if rate expectations haven't changed much.
Time
The longer the cap term, the more it costs — more time means more opportunities for rates to move above the strike. A 3-year cap costs meaningfully more than a 1-year cap at the same strike, not just because it covers more months, but because each additional month adds more uncertainty.
This is also why the back end of a cap (the later months) is often more expensive per caplet than the front end — there's more time for rates to move in unexpected ways.
Liquidity
Liquidity refers to how easily a cap can be bought or sold at a competitive price. The most liquid tenors and strikes — typically 2- to 5-year caps near current market rates — have tighter bid-ask spreads, meaning lower transaction costs. Less common structures (very short or long tenors, deep out-of-the-money strikes) tend to have wider spreads because fewer dealers actively quote them.
Market conditions also affect liquidity. During periods of heightened uncertainty or stress, dealers may widen their spreads across the board, making caps more expensive regardless of where rates or volatility are. This is why timing and dealer relationships can meaningfully impact the premium you pay.
Putting it together:
A cap is actually a bundle of individual monthly options called “caplets.” Each caplet covers one reset period. The total cap premium is the sum of all individual caplet costs. Caplets further out in time with higher forward rates and higher volatility are the most expensive components.
4. What is the Forward Curve?
The forward curve shows where the market expects interest rates to be in the future. It's derived from current market pricing of interest rate swaps and futures — not a forecast from any single analyst, but the consensus view implied by actual trading.
What it tells you:
- If the curve slopes downward, the market expects rate cuts ahead
- If it slopes upward, the market expects rate increases
- A flat curve suggests rates are expected to stay roughly where they are
How to read it:
On the Markets page, the forward curve plots projected 1-Month Term SOFR rates month by month into the future. Each point represents the market-implied SOFR setting for that future date.
For example, if today's 1-Month Term SOFR is 4.30% and the forward curve shows 3.50% in 12 months, the market is pricing in roughly 80 basis points of rate cuts over the next year.
Why it matters for cap pricing:
The forward curve is one of the primary inputs to cap pricing. Each caplet in your cap is priced based on the forward rate for that period:
- If the forward rate for a given month is above your strike, that caplet has intrinsic value (the market expects it to pay out)
- If the forward rate is below your strike, the caplet's cost is entirely time/option value
This is why cap pricing can change even if current SOFR hasn't moved — a shift in rate expectations further out the curve changes the expected payouts on future caplets.
Important caveat:
The forward curve is not a prediction. It's the market's current pricing of future rates, and it changes constantly. Actual SOFR settings can and often do differ significantly from what the forward curve implied months earlier. Think of it as the market's best estimate given today's information — useful for pricing and planning, but not a crystal ball.
5. Term SOFR 1-Month vs. SOFR Avg 30D: What's the Difference?
Not all SOFR-based loans use the same reference rate. The two most common indices for floating-rate commercial real estate loans are Term SOFR 1-Month and SOFR Average 30-Day. They sound similar, but they're structurally different — and the choice of index directly affects what you pay for a cap.
Term SOFR 1-Month (forward-looking):
Term SOFR 1-Month is set once at the start of each monthly accrual period, based on trading in SOFR futures. That single rate applies for the full month, and borrowers know their interest rate at the beginning of the period. Published by CME Group, it's the most common index for newer floating-rate loans and mirrors the way LIBOR used to work — which is why most borrowers find it familiar.
SOFR Avg 30D (backward-looking):
SOFR Average 30-Day is a trailing average. On any given day, it's the compounded average of the overnight SOFR rate over the preceding 30 days, published by the Federal Reserve Bank of New York. On most commercial real estate loans, including Fannie Mae and Freddie Mac floating-rate loans, the average published just before each accrual period is applied to the whole period. So you still know your rate at the start of the month. It just reflects the 30 days that came before rather than the market's view of the month ahead.
The key difference in one sentence:
Term SOFR looks forward — it reflects where the market expects rates to go. SOFR Avg 30D looks backward — it reflects where rates have already been.
How rate environments affect the comparison:
In a flat-rate environment, the two indices sit roughly on top of each other and cap premiums on either one are essentially interchangeable. In a changing-rate environment, though, they diverge — and that divergence shows up directly in the cap premium.
- Rising rates — Term SOFR 1M sits above SOFR Avg 30D, because the forward-looking rate is already pricing in future hikes while the trailing average is still dragging in older, lower rates. A cap on SOFR Avg 30D references the lower index, making it less likely to pay out. The premium is typically cheaper than an equivalent Term SOFR cap.
- Falling rates — Term SOFR 1M sits below SOFR Avg 30D, because the forward-looking rate is pricing in anticipated cuts while the trailing average is still catching up with higher rates from earlier. A cap on SOFR Avg 30D references the higher index, making it more likely to pay out. The premium is typically more expensive than an equivalent Term SOFR cap.
- Flat rates — The two indices converge and cap premiums are roughly the same. The choice of index doesn't meaningfully affect cost.
The intuition:
Because SOFR Avg 30D is a trailing average, it always lags the market. When rates are rising, lagging means lagging lower — which helps cap buyers. When rates are falling, lagging means lagging higher — which hurts cap buyers. Whichever direction the market is moving, the backward-looking index is always behind the forward-looking one.
Which index you'll actually use:
In practice, you usually don't get to pick. Your loan documents specify the index the loan accrues on, and your cap should match that index so the hedge lines up with the interest expense you're protecting. Mismatching the cap and loan indices creates basis risk — your cap can pay out based on one rate while your loan charges interest based on another, leaving a gap that defeats the purpose of hedging.
Quick reference:
6. What is an Interest Rate Floor?
An interest rate floor is the mirror image of a cap. While a cap pays out when rates rise above the strike, a floor pays out when rates fall below the strike. The mechanics are identical — notional, term, strike, and monthly resets — but the payout direction is reversed.
The floor payout formula:
Payout = Notional × max(Strike − SOFR, 0) × (Days in Period / 360)
If SOFR is at or above the strike, the floor payout is zero. If SOFR drops below the strike, the floor holder receives the difference.
Who uses floors:
- Lenders and investors holding floating-rate assets who want to protect against declining interest income
- Borrowers creating collar structures — buying a cap and selling a floor to reduce the net premium cost (see below)
Collars — caps and floors combined:
A collar combines a purchased cap with a sold floor. You buy protection against rates rising above your cap strike, and in exchange you sell away your benefit if rates fall below the floor strike. The premium received from selling the floor offsets part (or all) of the cap cost.
For example, you might buy a 4.50% cap and sell a 3.00% floor. Your SOFR rate is effectively bounded between 3.00% and 4.50% (your all-in rate adds the loan spread). If rates drop to 2.50%, you don't benefit from the savings below 3.00% — but your cap cost less upfront. When the floor premium fully offsets the cap premium, this is called a “zero-cost collar” — no upfront cost, but you give up all downside benefit below the floor strike.
How floor pricing works:
Floor pricing uses the same inputs as cap pricing — forward rates, volatility, and time — but pays out when rates fall below the strike instead of rise above it. A floor becomes more expensive when the market expects rates to fall significantly below the strike, and when volatility is elevated.
7. What is a Variable Strike Cap?
A variable strike cap (also called a “step-down” or “step-up” cap) uses different strike rates for different periods of the cap term, rather than a single fixed strike throughout.
How it works:
Instead of a uniform 4.00% strike for all 3 years, you might structure:
Each year's caplets use that year's strike rate when determining payouts and pricing.
Why use a variable strike:
The forward curve isn't flat — it typically slopes downward (or upward), meaning the market expects rates to change over time. A variable strike structure lets you align your cap more efficiently with rate expectations:
- Step-down strikes (higher early, lower later) — Common when rates are expected to decline. You accept a higher strike on the front end (when rates are high and the cap is expensive) and get a lower strike on the back end (when rates are expected to drop). This can be meaningfully cheaper than a flat low strike while still providing strong protection in later years.
- Step-up strikes (lower early, higher later) — Useful when you want maximum protection in the near term and are comfortable with more rate exposure later.
Lender requirements:
Not all lenders allow variable strikes. Check your loan documents to confirm.
8. What Are Counterparty Ratings and Downgrade Triggers?
When you purchase an interest rate cap, you're entering a contract with a bank (the “counterparty”) that promises to pay you if rates rise above your strike. Your lender wants to make sure that bank can actually pay.
Minimum counterparty ratings:
Most lenders require the cap provider to maintain a minimum credit rating, typically A- from S&P or A3 from Moody's. This ensures your cap is backed by a financially stable institution.
Downgrade triggers:
Your loan documents typically include a “downgrade trigger” — if the cap provider's credit rating falls below the minimum threshold, you're required to either:
- Replace the cap with a new one from an eligible provider, or
- Post additional collateral to secure the existing cap
This protects the lender (and you) from counterparty risk — the chance that the cap provider can't honor its obligations.
How ratings affect pricing:
Caps from higher-rated banks sometimes cost slightly more because you're paying for stronger credit backing. However, the difference is usually small because the major providers all maintain strong ratings.
What to watch for:
- Always confirm your lender's specific rating requirements before purchasing — some require A+/A1 or A/A2 (higher than the standard A-/A3)
- Agency lenders (Fannie Mae, Freddie Mac) have standardized requirements
- Debt funds may have more flexible or more restrictive requirements depending on the deal