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Secured Overnight Financing Rate (SOFR): Definition

Category — Rates
By Konstantin Vasilev Member of the Board of Directors of Cbonds, Ph.D. in Economics
Updated April 18, 2023

The Secured Overnight Financing Rate (SOFR) is a standard interest rate used in the United States to replace the London Interbank Offered Rate (LIBOR), which is discontinued. SOFR is based on overnight repo transactions secured by U.S. Treasury securities and is meant to be a more reliable indicator of market rates.

In this article, we will present a comprehensive definition of SOFR and discuss its use and implementation in the U.S. financial markets.

What is the Secured Overnight Financing Rate (SOFR)?

The Secured Overnight Financing Rate (SOFR) is an interest rate for the overnight borrowing of cash collateralized with US Treasury securities. It is intended to replace the London Interbank Offered Rate (LIBOR) as the standard reference rate for various financial contracts and transactions in the United States.

The need for a new benchmark rate arose because LIBOR was subject to controversies and scandals related to manipulation and lack of transparency. SOFR, in contrast, is based on actual transactions in the Treasury repurchase agreement (repo) market, which involves the buying and selling of Treasuries for short-term funding needs. This market is much larger and more diverse than the market for unsecured interbank loans that LIBOR was derived. SOFR is declared by the Federal Reserve Bank of New York on a daily basis.

SOFR is calculated by the New York Federal Reserve as a volume-weighted median of overnight repo transactions that occurred during a given business day. It is based on a subset of the repo market that is deemed to be most representative and liquid, although it excludes certain types of transactions. SOFR reflects the cost of borrowing cash overnight and giving Treasuries as collateral, which is a core funding activity for banks and other financial institutions.

SOFR has been adopted by many market participants for various purposes, including derivatives, loans, securitizations, and bonds. Some of the advantages of using SOFR over LIBOR include greater accuracy, transparency, and resilience, as well as the fact that SOFR is backed by the US government and is less susceptible to manipulation. However, there are also some challenges and uncertainties associated with the transition from LIBOR to SOFR, such as the differences in their methodologies, tenors, and credit risk components, as well as the need for market-wide coordination and education.

Secured Overnight Financing Rate (SOFR)

Understanding the Secured Overnight Financing Rate (SOFR)

SOFR is a benchmark interest rate used in the US financial markets. It is a replacement for the former benchmark rate, LIBOR (London Interbank Offered Rate), which is set to be replaced. SOFR is based on transactions in the tri-party and bilateral repurchase agreement (repo) market, which involves well-secured collateral as a form of a loan. The rate is published daily by the Federal Reserve Bank of New York, providing a reference rate for various financial instruments that use LIBOR as a benchmark, such as bonds, mortgages, and derivatives.

One of the key benefits of SOFR is its reliability and transparency. Unlike LIBOR, which was based on theoretical and subjective estimates submitted by large banks, SOFR is grounded on actual transactions in the repo market, making it less susceptible to manipulation. Moreover, being a US-based interest rate, it is less vulnerable to global political and economic risks that can affect international benchmark rates like LIBOR.

The adoption of SOFR as a benchmark rate has implications for different stakeholders in the financial industry. For investors and borrowers, it means adjusting to a new interest rate regime that can signal cost savings or increases for borrowing and lending. For financial institutions, it means adapting their systems and processes to incorporate SOFR as a benchmark and possibly transitioning certain contracts from LIBOR to SOFR. There are also implications for regulators who monitor and supervise the financial markets, as they need to ensure that the transition to SOFR is smooth, orderly, and consistent.

Given the importance of SOFR in the US financial markets, regulators and market participants are making efforts to ensure a successful transition from LIBOR. This includes developing guidelines and best practices for implementing SOFR, conducting awareness campaigns to educate stakeholders, setting up transition timelines and milestones, and addressing any legal or operational challenges that may arise. Ultimately, the successful transition to SOFR is critical for maintaining the stability, efficiency, and integrity of the US financial markets.

History of the Secured Overnight Financing Rate (SOFR)

The Secured Overnight Financing Rate (SOFR) was created by the Federal Reserve Bank of New York (FRBNY) in response to the 2008 financial crisis. The financial crisis exposed weaknesses in the financial markets, leading to concerns about the reliability of the existing benchmark interest rate (the London Interbank Offered Rate, or LIBOR), which was based on estimates rather than actual transactions.

To address these concerns, the FRBNY began exploring alternative benchmark rates based on actual transaction data. In 2014, the Alternative Reference Rates Committee (ARRC) was established to identify and promote an alternative rate to LIBOR. The ARRC comprises a group of industry experts, including banks, asset managers, and market regulators.

After evaluating various rates, the ARRC recommended SOFR as the preferred alternative to LIBOR in 2017. SOFR is based on actual overnight transactions in the repurchase agreement (repo) market, where banks and other financial institutions borrow and lend cash overnight with Treasury securities serving as collateral.

SOFR is considered a more reliable benchmark rate than LIBOR because it is based on actual transactions rather than estimates. It is also designed to be more resistant to manipulation, which was a concern with LIBOR. Additionally, the repo market is much larger than the unsecured markets that LIBOR is based on, making SOFR a more representative benchmark rate.

Since its introduction, SOFR has gained significant traction in the market. In 2018, the first SOFR-linked securities were issued, and in 2019, several banks began using SOFR as an alternative to LIBOR in derivative contracts. The ARRC has also developed a robust plan for the transition from LIBOR to SOFR, with the goal of fully transitioning.

Overall, the development of SOFR represents an important step forward in improving the reliability and integrity of benchmark interest rates in financial markets. While the transition from LIBOR to SOFR poses challenges for market participants, it is a necessary step towards a more stable and resilient financial system.

Additions to Secured Overnight Financing Rate (SOFR)

There are various types of additions of SOFR that financial institutions may use, each with a slightly different methodology and purpose.

The FRBNY publishes the SOFR Averages and SOFR Index on a daily basis, aside from the Secured Overnight Financing Rate.  SOFR Averages are compounded of the SOFR over rolling 30-, 90-, and 180-calendar days, while SOFR Index shows the effect of compounding the SOFR each business day and gives option for the calculation of compounded SOFR averages over custom time periods. 

Also, CME Group Benchmark Administration Ltd presently releases Term SOFR Reference Rates for tenors of one, three, and six months. 

Overall, SOFR is an alternative to LIBOR and is calculated using the cost of overnight borrowing collateralized by U.S. Treasury securities. SOFR has additions: SOFR Averages, SOFR Index, Term SOFR. Both SOFR Averages, SOFR Index are backward-looking rates, while Term SOFR is forward-looking. The choice of which indicator to use depends on the individual needs and requirements of each financial product.

Transition to the Secured Overnight Financing Rate (SOFR)

SOFR is based on overnight transactions in the U.S. Treasury repurchase market, which makes it a more reliable and transparent benchmark than LIBOR. LIBOR is in the process of being phased out, so the lenders use SOFR to issue new loans. 

Transitioning to SOFR requires significant changes to financial markets and regulatory frameworks. This transition impacts a wide range of financial products and services that currently use LIBOR and may result in significant operational and financial risks for market participants. To prepare for these changes, it is essential that market participants understand the differences between SOFR and LIBOR and the implications of this transition.

Transitioning to SOFR requires market participants to update their systems, contracts, and risk management practices. This needs significant investment in technology and infrastructure, which may create operational and financial risks. To minimize these risks, market participants prepared for the transition by identifying their exposures to LIBOR and assessing the impact of the transition on their business.

SOFR transition challenges

The SOFR (Secured Overnight Financing Rate) transition is still an ongoing challenge for financial institutions in the United States. The SOFR is a preferred alternative reference rate to the LIBOR (London Interbank Offered Rate), which is being phased out because of concerns about its reliability and accuracy.

Adapting systems and processes to accommodate the new rate. The SOFR is based on overnight repurchase agreements, which can differ significantly from longer-term loans that were used to determine the LIBOR. Financial institutions must update their systems and processes to ensure they are able to calculate and manage new rates accurately.

Managing risks associated with the volatility of the SOFR. The overnight rate can fluctuate significantly, which could cause major fluctuations in financial products and markets. Institutions must understand the risks associated with the SOFR, especially in comparison to the LIBOR, and actively manage these risks through both internal controls and by implementing SOFR derivatives to help protect against volatility.

Legal challenges. These challenges include contracts and financial instruments, such as bonds and loans, that refer to LIBOR must be modified to reference the SOFR. This can be a complex process as the interests of different parties may need to align, and legal documents may need to be renegotiated in order to accommodate SOFR.

Market-wide adoption. As noted earlier, LIBOR is in the process of being phased out. Convincing market participants to change their practices and habits can be slow and difficult, so the SOFR transition requires cooperation and a shared understanding among market participants to ensure successful implementation.


  • What is the current SOFR rate?

  • What is SOFR vs LIBOR?

  • Is SOFR replacing LIBOR in the US?

  • What are additions of SOFR?

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