What Is the Secured Overnight Financing Rate (SOFR)?

The Secured Overnight Financing Rate (SOFR) is a benchmark interest rate that reflects the cost of borrowing cash overnight using U.S. Treasury securities as collateral. It is published by the Federal Reserve Bank of New York and has become the primary replacement for the London Interbank Offered Rate (LIBOR) in the United States. SOFR plays a critical role in the financial system by influencing rates on everything from adjustable-rate mortgages to derivatives contracts.

Unlike LIBOR, which was based on estimates from banks, SOFR is derived from actual transactions in the overnight repurchase agreement (repo) market. This makes it a more transparent and reliable measure of short-term borrowing costs.

How SOFR Is Calculated

SOFR is based on the volume-weighted median of overnight repo transactions secured by U.S. Treasury securities. These transactions occur in a large and active market where institutions such as banks, mutual funds, and government-sponsored enterprises borrow and lend cash overnight in exchange for Treasury securities as collateral.

The Federal Reserve Bank of New York collects data from three major repo market segments:

1. Tri-party repo transactions settled through the Bank of New York Mellon
2. General Collateral Finance (GCF) Repo transactions cleared through the Fixed Income Clearing Corporation
3. Bilateral repo transactions cleared through the Depository Trust & Clearing Corporation (DTCC)

Once the data is aggregated, the New York Fed calculates a volume-weighted median rate and publishes the SOFR value at approximately 8:00 a.m. Eastern Time each business day, reflecting the previous day’s activity.

Transition from LIBOR to SOFR

SOFR gained prominence as part of the global effort to move away from LIBOR, which had been plagued by manipulation scandals and declining transaction volumes. LIBOR was based on submissions from a panel of banks estimating the cost of unsecured borrowing, making it vulnerable to conflicts of interest and inaccuracies.

In response, regulators around the world began identifying alternative reference rates rooted in actual transactions. In the U.S., the Alternative Reference Rates Committee (ARRC), a group convened by the Federal Reserve and the New York Fed, selected SOFR as the preferred alternative to U.S. dollar LIBOR.

SOFR's adoption accelerated after regulators set firm deadlines for phasing out LIBOR. As of mid-2023, most new contracts in U.S. markets have transitioned to using SOFR instead of LIBOR.

Key Characteristics of SOFR

SOFR differs from LIBOR and other benchmark rates in several important ways:

• Secured vs. Unsecured: SOFR is based on secured loans backed by Treasury securities, whereas LIBOR was based on unsecured bank lending. This means SOFR generally reflects a lower risk premium and therefore tends to be lower than LIBOR.
• Overnight vs. Term: SOFR is an overnight rate. While LIBOR was published in various tenors (such as one-month or three-month rates), SOFR represents the cost of overnight borrowing. However, term SOFR rates based on futures markets and derivatives have been developed to meet the needs of borrowers and lenders requiring longer timeframes.
• Transaction-Based: The calculation of SOFR is rooted in a broad and active market, making it less susceptible to manipulation. This enhances its credibility as a benchmark.

Applications in Financial Markets

SOFR is now used in a wide range of financial products, including:

• Floating-rate debt instruments
• Adjustable-rate mortgages
• Derivatives such as interest rate swaps and futures
• Business loans and corporate credit facilities

Financial institutions often add a spread to SOFR to account for differences in credit risk or other factors not reflected in the base rate. For example, a mortgage might be priced at “SOFR + 2.50%” to determine the total interest rate paid by the borrower.

To facilitate usage in contracts, daily SOFR values can be compounded over a specific time period. This compounded SOFR can serve as a backward-looking interest rate that reflects average borrowing costs over time, which is especially useful for loan products and securitized assets.

Challenges and Considerations

Despite its advantages, SOFR’s transition into widespread use has not been without challenges. One of the main concerns among lenders and borrowers has been the lack of a credit component in SOFR. Since SOFR is based on secured transactions, it doesn’t account for the risk of lending to banks or other institutions in the way LIBOR did.

Additionally, the use of a backward-looking rate like SOFR required adjustments in how interest is calculated and reported in financial contracts. The development of forward-looking term SOFR rates has helped address some of these concerns, especially for industries accustomed to knowing interest obligations in advance.

Legal and operational considerations also had to be addressed during the transition, including the use of fallback language in existing contracts and the adjustment of systems and processes to accommodate SOFR-based instruments.

The Bottom Line

The Secured Overnight Financing Rate (SOFR) has become the central benchmark interest rate for U.S. dollar-denominated financial markets, replacing LIBOR due to its stronger foundation in actual market activity and lower susceptibility to manipulation. While it brings greater transparency and stability, it also requires a shift in how financial products are structured and understood. As adoption continues, SOFR is shaping a new standard for interest rate benchmarks in the modern financial system.