Floating-Rate Bonds: Features, Spread Measures & SOFR Transition

Published: April 9, 2026

Article by Ryan O'Connell, CFA, FRM

Rising interest rates devastate fixed-rate bond prices, but floating-rate bonds offer a solution: their coupons automatically adjust when rates move. Whether you’re managing interest rate risk in a portfolio, analyzing credit instruments, or studying fixed income markets, understanding floaters is essential. This guide covers coupon mechanics, the LIBOR-to-SOFR transition, spread measures (quoted margin vs. discount margin), why floaters have near-zero duration, and how caps and floors affect their behavior. For the mechanics of converting floating-rate exposure to fixed, see our guide on interest rate swaps.

What Are Floating-Rate Bonds?

A floating-rate bond (also called a floater or FRN — floating-rate note) is a debt security whose coupon payment resets periodically based on a short-term reference rate plus a fixed spread. Unlike fixed-rate bonds where the dollar coupon is locked in at issuance, a floater’s coupon changes each reset period as the benchmark rate moves.

For example, a floater with a quoted margin of +150 basis points over 3-month SOFR will pay a 6.30% coupon when SOFR is 4.80%, and a 5.10% coupon if SOFR falls to 3.60%. The coupon adjusts automatically — no action required from the investor or issuer.

Most corporate and agency floaters reset quarterly with coupon payments made in arrears. The reset mechanism determines when the reference rate is observed: Term SOFR is typically set in advance at the beginning of each interest period, while overnight SOFR may be compounded or averaged in arrears over the period. This distinction matters for cash flow forecasting but doesn’t change the fundamental low-duration characteristic of floaters.

Reference Rates: From LIBOR to SOFR

Every floater needs an observable, liquid benchmark to anchor its floating leg. For decades, that benchmark was LIBOR — the London Interbank Offered Rate. LIBOR’s demise and SOFR’s rise represent one of the most significant structural changes in fixed income markets in a generation.

The LIBOR Era and Its End

LIBOR was published daily in five currencies and seven maturities (overnight to 12 months), based on submissions from panels of major banks estimating their unsecured borrowing costs. At its peak, over $300 trillion in financial contracts referenced LIBOR. However, the rate had a fundamental flaw: it was based on hypothetical transactions and “expert judgment” rather than actual trades.

The 2012 LIBOR scandal revealed widespread manipulation, undermining confidence in the benchmark. On July 27, 2017, the UK Financial Conduct Authority announced it would no longer compel banks to submit LIBOR quotes after 2021. USD LIBOR panel settings officially ceased on June 30, 2023, though synthetic 1-month, 3-month, and 6-month USD LIBOR continued until September 30, 2024 to support legacy contracts.

CME Group publishes Term SOFR rates in 1-month, 3-month, and 6-month tenors, addressing the operational challenge that overnight SOFR doesn’t provide a forward-looking term structure. However, ARRC guidance recommends overnight SOFR compounded in arrears (or SOFR averages) for most floating-rate notes, reserving Term SOFR primarily for business loans and trade finance where cash flow certainty is critical. Corporate and agency FRNs increasingly use daily SOFR compounded over the interest period.

Spread Measures for Floaters

Two spread concepts are essential for understanding floating-rate bonds. The quoted margin is what the issuer promised; the discount margin is what you actually earn given the current market price. A third concept — required margin — represents what the market currently demands for similar credit risk, and drives price movements.

Quoted Margin

The quoted margin (QM) is the fixed spread over the reference rate, set at issuance and unchanged for the bond’s life. It reflects the credit risk and liquidity characteristics of the issuer at the time the bond was sold.

Required Margin and Price Movements

The required margin is the spread the market currently demands for the issuer’s credit risk. When required margin exceeds quoted margin, the bond trades below par. When required margin is less than quoted margin, the bond trades above par. This relationship is central to Fabozzi’s framework for floater price volatility:

• Required margin > Quoted margin → Bond trades at a discount (below par)
• Required margin = Quoted margin → Bond trades at par
• Required margin < Quoted margin → Bond trades at a premium (above par)

Discount Margin

The discount margin (DM) is the spread over the reference rate that, when used to discount all projected future cash flows, produces a present value equal to the bond’s market price. It is the floating-rate equivalent of yield to maturity for fixed-rate bonds and is solved iteratively.

The discount margin assumes the reference rate stays flat at today’s level throughout the bond’s remaining life — a simplifying assumption. For a more sophisticated measure that uses the full SOFR term structure, analysts calculate the Z-DM (zero-discount margin), analogous to the Z-spread for fixed-rate bonds.

Why Floaters Have Low Duration

The defining characteristic of floating-rate bonds is their near-zero interest rate duration. This is why institutional investors use floaters to reduce portfolio sensitivity to rate movements.

The intuition is straightforward: because the coupon resets to match the current interest rate environment, the bond’s price doesn’t need to move much when rates change. Any price deviation caused by a rate move between resets is corrected at the next reset date.

However, near-zero rate duration does not mean near-zero total risk. Floaters still carry two important duration exposures:

1. Spread duration (credit duration): The quoted margin is fixed at issuance. If the issuer’s creditworthiness deteriorates and the market-required margin increases, the bond price falls — even if the reference rate hasn’t changed. A 10-year floater from a BBB-rated issuer has significant spread duration.
2. Reset risk: Floaters with longer reset periods (semi-annual or annual) have higher rate duration. A floater resetting every 12 months has duration up to approximately 1 year immediately after a reset.

Caps and Floors on Floating-Rate Notes

Not all floaters allow the coupon to move without limit. Many include embedded options that constrain the coupon to a defined range. For a broader treatment of embedded options in fixed income, see our guide on callable bonds and embedded options.

Cap: A maximum coupon rate the issuer will pay, regardless of how high the reference rate rises. The cap protects the issuer but limits investor upside. If 3-month SOFR plus the quoted margin would produce a 10% coupon but the bond has an 8% cap, the investor receives only 8%.

Floor: A minimum coupon rate, regardless of how low the reference rate falls. The floor protects the investor. If SOFR plus the quoted margin would produce a 2% coupon but the bond has a 3% floor, the investor receives 3%.

Collar: A combination of cap and floor that constrains the coupon to a defined range — for example, between 3% and 8%.

Example: Capped Floater

Consider a hypothetical 5-year agency floater: 3-month SOFR + 75 basis points, capped at 6.50%. If SOFR rises to 6.00%, the uncapped coupon would be 6.75%, but the investor receives only the 6.50% cap. Any further increase in SOFR provides no additional coupon benefit, while the bond now trades with duration risk because its effective coupon is fixed at the cap.

For detailed coverage of standalone interest rate caps and floors as derivative instruments, see our guide on interest rate caps and floors.

Who Issues and Buys Floaters

Issuers

Banks and financial institutions are natural issuers of floating-rate debt because their assets (loans) are often floating-rate. Issuing floating-rate liabilities aligns funding costs with asset yields, reducing interest rate mismatch risk.

Government-sponsored enterprises (Freddie Mac, Fannie Mae, Federal Home Loan Banks) are among the largest FRN issuers. The U.S. Treasury has issued floating-rate notes since January 2014.

Investment-grade corporates issue floaters when they want lower initial borrowing costs or when the interest rate outlook favors floating-rate issuance.

Leveraged borrowers in the sub-investment-grade market typically borrow through floating-rate term loans (not bonds) — these are an adjacent floating-rate credit market with similar mechanics but different trading and documentation conventions.

Buyers

Money market funds and short-term cash managers buy floaters for their near-zero duration and typically high credit quality (agency or investment-grade).

Bank loan funds and CLOs (collateralized loan obligations) invest primarily in leveraged floating-rate loans, seeking yield while maintaining low rate duration.

Insurance companies and pension funds use floaters when their liability structure doesn’t require long fixed-income duration or when they expect rates to rise.

Corporate treasury departments park cash reserves in high-quality floaters to earn yield without duration risk.

Fixed-Rate vs. Floating-Rate Bonds

The choice between fixed and floating isn’t just about predicting rate direction. It also reflects the investor’s liability structure, the issuer’s asset-liability management needs, and whether embedded options (caps, floors, or call provisions) change the risk profile.

How to Analyze Floating-Rate Bonds

Evaluating a floating-rate note requires examining several factors beyond just the quoted margin:

1. Reset frequency: More frequent resets (weekly, monthly) mean lower duration. Less frequent resets (semi-annual, annual) introduce more rate sensitivity between resets.
2. Quoted margin vs. required margin: Compare the bond’s quoted margin to what similar-credit issuers are currently offering. If required margins have widened since issuance, expect the bond to trade at a discount.
3. Discount margin: Calculate or obtain the DM to understand your actual yield pickup over the reference rate, accounting for the current price.
4. Cap and floor terms: Check if the floater has embedded options. How far is the current reference rate from the cap? In a rising rate scenario, could the cap become binding?
5. Fallback language: For legacy bonds originally referencing LIBOR, verify the fallback provisions. ARRC-recommended language is standard, but older bonds may have discretionary or incomplete fallbacks.
6. Liquidity: Corporate floaters often trade in thinner markets than Treasury securities. Assess bid-ask spreads and typical trade sizes.

Limitations of Floating-Rate Bonds

1. Credit and Spread Risk: The quoted margin is fixed at issuance. If the issuer’s creditworthiness deteriorates, the market demands a higher spread and the bond price falls — regardless of reference rate movements. A floater is not immune to credit-driven price declines, only rate-driven ones. See credit risk for more on default and spread risk, and corporate bond credit analysis for issuer evaluation frameworks.

2. Cap Risk: When reference rates rise above the cap level, the floater loses its floating-rate character and behaves like a fixed-rate bond. Investors who bought floaters for duration protection may face unexpected interest rate sensitivity.

3. Benchmark Transition Risk: The LIBOR cessation demonstrated that reference rates can change. Existing bonds with inadequate fallback language may create ambiguity. While ARRC-recommended provisions are now standard, legacy bonds with discretionary or incomplete fallbacks carry transition risk.

4. Liquidity Risk: Many corporate floating-rate notes trade in thinner markets than Treasury securities. Bid-ask spreads are wider, and in stressed conditions, executing large trades at fair prices can be difficult. This liquidity risk is often embedded in wider Z-spreads.

Common Mistakes

1. Confusing Quoted Margin with Discount Margin: Investors sometimes assume that if they buy a floater with a 200 bps quoted margin, they will earn 200 bps over the reference rate. That’s only true at par. If the bond trades at $970, DM exceeds 200 bps; at $1,020, DM is less than 200 bps. Always calculate or obtain the discount margin based on your actual purchase price.

2. Assuming Zero Duration Means Zero Risk: Near-zero rate duration does not mean near-zero total risk. A 10-year floater from a BBB issuer has significant spread duration — if the issuer’s credit spread widens by 100 bps, the bond price falls meaningfully, even with stable reference rates.

3. Ignoring Cap Risk in Rising-Rate Environments: Investors often buy capped floaters without checking how close the cap is to current rates. A cap of 7% may seem irrelevant when SOFR is 3%, but if SOFR rises to 6% and the quoted margin is 150 bps, the floater is at the cap — further rate increases provide no additional coupon benefit while introducing fixed-rate duration risk.

4. Using YTM Instead of Discount Margin: Yield to maturity assumes fixed cash flows and is inappropriate for floaters whose coupons reset periodically. Using YTM on a floater produces a misleading yield estimate. Always use discount margin or Z-DM for floating-rate securities.

5. Treating All Reference Rates as Equivalent: SOFR is secured and essentially risk-free; LIBOR included a bank credit premium. When comparing spreads across bonds indexed to different benchmarks, account for the approximately 26 bps credit spread adjustment (for 3-month tenor) that separates SOFR from what LIBOR would have been.