Alternative reference rates are robust benchmark replacements used after IBOR reform; each currency has its own overnight rate, conventions, term variants, and fallbacks.
Alternative reference rates (ARRs) are benchmark rates selected or developed as more robust alternatives to discontinued or reformed interbank offered rates such as LIBOR. Most major ARRs are based on deep overnight funding markets, but there is no single global ARR and no universal method for replacing an old benchmark in every contract.
The term should not be confused with the Alternative Reference Rates Committee (ARRC), the U.S. private-market group convened by the Federal Reserve Board and Federal Reserve Bank of New York. ARRC is a committee; an alternative reference rate is a benchmark category.
| Currency | Benchmark | Underlying market | Administrator |
|---|---|---|---|
| U.S. dollar | SOFR | Secured overnight Treasury repurchase transactions | Federal Reserve Bank of New York |
| Sterling | SONIA | Unsecured overnight sterling wholesale deposits | Bank of England |
| Euro | €STR | Unsecured overnight euro wholesale borrowing | European Central Bank |
| Japanese yen | TONA | Uncollateralized overnight call transactions | Bank of Japan |
| Swiss franc | SARON | Secured Swiss franc repo transactions | SIX Swiss Exchange |
| Singapore dollar | SORA | Unsecured overnight SGD interbank transactions | Monetary Authority of Singapore |
These rates fill similar benchmark roles, but they are not interchangeable. A dollar contract cannot substitute SONIA for SOFR, and a secured rate such as SOFR or SARON has different economic content from an unsecured rate such as SONIA or €STR.
LIBOR was based on panel-bank assessments of unsecured term funding. As activity in the underlying markets declined, the benchmark increasingly depended on judgment rather than a deep set of transactions. Manipulation cases also exposed weaknesses in benchmark governance.
Official-sector and market working groups therefore promoted benchmarks grounded in active markets and robust methodologies. The goal was not to create risk-free investments. The phrase risk-free rate in this context means the benchmark contains relatively little bank-credit risk because it is overnight, secured, or both.
The benchmark can still carry operational, liquidity, basis, legal, and market risks.
Most primary ARRs are overnight rates. A three-month loan, however, needs a rate covering a longer interest period.
Daily overnight observations can be compounded over the accrual period. A simplified daily compounding factor is:
where (r_i) is the overnight rate for observation (i), (d_i) is the number of calendar days for which it applies, and (D) is the contractual day-count denominator.
The annualized period rate depends on the agreement’s compounding, lookback, observation shift, non-business-day, and rounding rules. It becomes fully known near the end of the period.
Some products use a simple average rather than daily compounding. This produces different interest from a compounded convention, especially over longer periods or when rates vary.
Some markets permit term rates derived from derivatives referencing the overnight benchmark. A term rate can be known near the start of the period, but it is a separate administered benchmark with its own permitted-use guidance and licensing conditions.
The Financial Stability Board has emphasized broad use of robust overnight rates while recognizing a limited role for RFR-derived term rates in some products.
Suppose a legacy loan paid three-month LIBOR plus 2.00%. An amendment replaces LIBOR with compounded overnight ARR plus a fixed 0.25% transition adjustment while preserving the 2.00% loan margin.
If compounded ARR for the period is 4.10%, the annualized all-in rate is:
For a $10 million principal and a 90-day Actual/360 period, illustrative interest is:
The 0.25% is an invented example, not a market-standard adjustment. Actual fallback spreads and effective dates depend on the currency, tenor, product, governing law, and contract language.
| Contract feature | Old term IBOR | Overnight ARR replacement |
|---|---|---|
| Rate timing | Usually fixed near period start | Commonly compounded and finalized near period end |
| Credit content | Included unsecured term bank funding | Usually contains less bank-credit and term-liquidity risk |
| Data operations | One term fixing | Daily rates, calendars, compounding, and index data |
| Payment notice | Longer advance notice | May require lookback or payment delay |
| Spread | Original contractual margin | Original margin may remain, with a separate transition adjustment |
| Hedge alignment | IBOR loan and IBOR swap | Replacement conventions must match across loan and hedge |
A fallback can produce a valid payment without making the replacement economically identical to the original benchmark.
Confirm:
This article provides general financial education, not personalized investment, borrowing, accounting, tax, or legal advice. Use governing documents and current official benchmark publications for any live calculation or transition decision.