Overnight and Risk-Free Benchmarks

Overnight benchmarks measure one-business-day wholesale funding and provide the foundation for many post-LIBOR loans, bonds, derivatives, and valuation curves. “Risk-free rate” is market shorthand: these benchmarks generally contain limited bank-credit risk, but the linked contract and instrument still carry basis, liquidity, operational, legal, and counterparty risks.

The benchmark name alone does not determine a cash flow. A contract may use one daily observation, a simple average, daily compounding in arrears, an official index, or a forward-looking term rate derived from overnight markets.

Major Overnight Benchmarks

Other currency frameworks include SARON for Swiss francs and SORA for Singapore dollars. The Alternative Reference Rates guide compares their role in benchmark transition.

Secured and Unsecured Rates

SOFR is secured by U.S. Treasury collateral. SONIA, €STR, and TONA are unsecured overnight benchmarks. This distinction changes the economic input:

• Secured rate: affected by cash demand, collateral supply, repo-market structure, and balance-sheet capacity.
• Unsecured rate: affected by wholesale deposit conditions and the credit characteristics of eligible borrowers, though overnight maturity limits exposure.

A secured rate is not guaranteed to be lower than every unsecured rate. Currency, central-bank policy, collateral scarcity, market segmentation, and timing all matter.

Daily Rate, Compounded Rate, or Term Rate

Two contracts that both say “SOFR” or “SONIA” can produce different payments if one compounds with an observation shift and the other uses a five-business-day lookback without shifting day weights.

Example: Same Benchmark, Different Convention

Suppose a loan and its hedge both reference SONIA. The loan uses a five-day lookback without observation shift, while the swap uses an observation shift. During a period in which daily rates change, the two compounded amounts can differ because rates are paired with calendar-day weights differently.

The benchmark name matches, but the conventions create basis risk. A treasury review should compare observation periods, weekend weighting, day count, floors, rounding, and payment delays across both contracts.

Why Overnight Benchmarks Replaced LIBOR

Historical LIBOR settings represented unsecured term bank funding and relied heavily on panel-bank submissions as underlying transaction markets declined. Major overnight benchmarks are tied to broader, more active transaction sets.

That improves robustness but does not make the rates economically identical. Overnight replacements usually contain less term bank-credit and liquidity risk, and their payment timing differs. Fallback spread adjustments address part of that difference, while systems and documents must address the rest.

Contract Checklist

Before calculating or valuing an overnight-linked cash flow, identify:

• official benchmark and administrator
• currency and secured or unsecured market
• transaction date versus publication date
• daily, averaged, compounded, index, or term form
• accrual and observation periods
• lookback, observation shift, or lockout
• weekend and holiday weighting
• day-count denominator and rounding
• benchmark floor, contract margin, and transition adjustment
• temporary and permanent fallback provisions
• data source and licensing rights

Common Mistakes

• Treating “near risk-free” as a guarantee of safety or repayment.
• Calling every overnight benchmark an interbank lending rate.
• Using one daily fixing for a multi-month accrual period.
• Mixing secured and unsecured rates without explaining the basis.
• Assuming a policy rate and a transaction benchmark are identical.
• Treating EONIA as active or adding its old 8.5-basis-point spread to current €STR contracts.
• Comparing historical LIBOR and replacement-rate series without documenting methodology breaks.

Official Sources

• Federal Reserve Bank of New York, SOFR
• Federal Reserve Bank of New York, SOFR Averages and Index
• Bank of England, SONIA benchmark
• European Central Bank, €STR
• Bank of Japan, uncollateralized overnight call rate
• Financial Stability Board, overnight risk-free rates and term rates

This section provides general financial education, not personalized investment, borrowing, accounting, tax, or legal advice. Use the governing contract and current administrator publications for calculation, valuation, or settlement.

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