SUNANDO ROY – On Banking, Finance and Society

Introduction

The transition from LIBOR to alternative reference rates has reshaped financial markets, with the Alternative Reference Rates Committee (ARRC) guiding the U.S. shift toward the Secured Overnight Financing Rate (SOFR). Designed to be transparent, transaction-based, and grounded in the U.S. Treasury repo market, SOFR provides a robust benchmark for modern financial instruments. As SOFR adoption accelerated, market participants quickly recognized that a single overnight rate could not support the full diversity of cash products, loans, derivatives, and retail credit markets. In response, several distinct SOFR variants emerged, each tailored to different operational, risk, and transparency needs. Understanding their construction and use cases is essential for institutions seeking accurate pricing, effective hedging, and smooth post-LIBOR operations.

Definitions of Key SOFR Rates

1. Daily Compounded SOFR (In Arrears)

Daily Compounded SOFR in arrears is the most precise and market-aligned form of the rate. It is calculated by compounding the overnight SOFR for each day of the interest period, producing an accurate measure of the actual cost of secured overnight borrowing. Because the compounding cannot be completed until the end of the accrual period, the final interest rate is only known at maturity. This backward-looking nature makes the rate optimal for derivatives, wholesale funding, and institutional instruments where accuracy, fairness, and comparability to market funding conditions are more important than early rate visibility. Central clearinghouses (CCPs) use this form of SOFR for interest rate swaps, reinforcing it as the standard for derivatives markets.

2. Term SOFR

Term SOFR is a forward-looking benchmark that provides interest rates for one-, three-, six-, and twelve-month tenors at the start of each interest period. It is derived from SOFR futures markets and published by CME Group under ARRC endorsement for permitted use cases. Because borrowers know their interest obligation in advance, Term SOFR simplifies operational processes and enhances transparency for lenders and consumers alike. These qualities make it particularly suitable for syndicated loans, business credit facilities, trade finance, and many retail banking products. While Term SOFR offers clarity and ease of use, it is intentionally limited in derivatives markets to avoid creating vulnerabilities similar to those experienced under LIBOR.

3. SOFR Averages (30-, 90-, and 180-Day)

SOFR Averages are simple arithmetic averages of the overnight SOFR over the preceding 30, 90, or 180 days. These averages provide a stable and predictable rate that smooths short-term volatility in the overnight market. Because they rely solely on historical data, they are easy to calculate, understand, and implement across smaller institutions or legacy systems that may lack the infrastructure to support daily compounding. SOFR Averages are commonly used in consumer products, small-business lending, internal transfer pricing, and scenarios where operational simplicity outweighs the precision offered by compounded measures.

4. SOFR Index

The SOFR Index is a continuously compounded measure published by the Federal Reserve that tracks the growth of $1 invested at the overnight SOFR rate since April 2018. Institutions use the index to calculate compounded SOFR over any arbitrary period simply by dividing the index values at the start and end of the interest window. This approach eliminates the need to store or recalculate daily compounding formulas and enhances consistency across systems. The SOFR Index is especially useful for products with nonstandard accrual periods, for institutions building internal interest engines, and for scenarios requiring customized compounding intervals.

Matching SOFR Rates to Contract Characteristics

The appropriate SOFR rate depends on the structure and needs of the contract. Derivatives markets rely on compounded SOFR in arrears because it best captures real-time funding costs and aligns with central clearinghouse conventions. Corporate and syndicated loans favor Term SOFR, which provides the rate at the beginning of the interest period, simplifying payment forecasting and documentation. Retail credit products, including mortgages and personal loans, often adopt Term SOFR or SOFR averages due to their clarity and consumer familiarity. Floating-rate notes may reference either compounded SOFR or Term SOFR, depending on investor preference and system capacity. Trade finance and working capital arrangements typically use Term SOFR, as predictable interest obligations are essential for financial planning.

A comparison of typical instrument preferences appears in the table below:

Contract size and tenor further shape the choice of SOFR variant. Large institutional transactions commonly choose compounded SOFR for precision and hedging alignment, mid-sized commercial contracts gravitate toward Term SOFR to reduce operational burdens, and smaller or retail-focused contracts often rely on SOFR averages or Term SOFR for their ease of use. Short maturities align naturally with compounded or average SOFR, while medium-term exposures benefit from Term SOFR’s upfront visibility. Longer-term structures often prefer compounded SOFR to minimize basis risk across extended accrual periods.

Managing Basis Risk Across SOFR Variants

Because each SOFR measure behaves differently, using one variant to hedge exposure in another can create basis risk. A common example involves hedging a Term SOFR-based loan with a swap tied to compounded SOFR in arrears. The divergence in timing, calculation, and visibility between the rates may lead to cash flow mismatches and hedge inefficiency. Institutions therefore implement formal basis adjustments, align internal transfer pricing to a consistent benchmark, and use derivative overlays to offset timing or structural differences. As markets continue to mature, the ability to anticipate and manage SOFR-based basis risk will remain a central component of sound balance sheet strategy.

The evolution of SOFR into a family of related benchmarks reflects the need for a modern, flexible, and transparent reference rate system capable of supporting the diverse landscape of today’s financial markets. Term SOFR has established itself as the benchmark of choice for cash markets requiring straightforward and predictable rate setting, while compounded SOFR in arrears remains foundational for derivatives and wholesale funding. SOFR averages and the SOFR Index fill essential roles for simpler systems, consumer products, and custom accrual structures. As institutions refine their post-LIBOR frameworks, aligning rate choice with contract design, risk management priorities, and operational capabilities will be critical to maintaining both accuracy and market stability.

References 

Alternative Reference Rates Committee. ARRC Recommended Best Practices for Completing the Transition from LIBOR. Federal Reserve Bank of New York, 2021.

CME Group. Term SOFR Reference Rates Methodology. Chicago: CME Group.

Duffie, Darrell, and Yang Song. “LIBOR Transition and the SOFR Ecosystem.” Stanford Graduate School of Business Working Paper, 2022.

Federal Reserve Bank of New York. “The Secured Overnight Financing Rate (SOFR).” Accessed 2018–2024.