By
Maxim Zenkov, Head of Indian Fixed Income Market of Cbonds
Updated June 28, 2024
What is an Overnight Index Swap?
An overnight index swap, often abbreviated as OIS, is a financial contract designed to manage interest rate risk. In this hedging agreement, two parties agree to exchange a predetermined cash flows dor a certain time. Unlike conventional fixed-rate swaps, an overnight index swap involves the use of an overnight rate index, such as the federal funds rate or the London Interbank Offered Rate (LIBOR). Terms of the contract range from as short as one day to more extended periods beyond one year.
This derivative contract plays a crucial role in financial markets, providing a mechanism for parties to manage their exposure to short-term interest rates. It is particularly relevant for institutions such as pension funds, hedge funds, and other financial institutions looking to optimize their portfolios and navigate fluctuations in interest rates.

Understanding Overnight Index Swaps
Overnight Index Swap has a fixed leg and a floating leg. One side agrees to pay the floating interest on a notional principle based on a certain overnight rate (e.g., Effective Federal Funds Rate) over the contract period. In exchange, the other party commits to pay the mutually agreed fixed rate up to the end of the swap agreement. On the pre-agreed date, after the floating and fixed interest payment obligations of the two sides accrued over the period are contrasted, the monetary difference is settled.
The determination of the floating leg value can be approached in two ways: either through the compounding of the overnight rate or by calculating the geometric average of the rate throughout the agreement. Financial institutions favor overnight index swaps for several reasons. They utilize OIS contracts to gain protection against potential increases in the overnight rate or, conversely, to bet on the expected decrease in interest rates. Beyond risk mitigation, OIS also functions as a benchmark for pricing other financial instruments, contributing to the overall efficiency and transparency of financial markets.
Participants in the Overnight Index Swap Market
- Banks and Insurance Companies are key participants in the OIS market. They actively engage in these swaps to manage their exposure to interest rate fluctuations and to speculate on potential movements in interest rates.
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Hedge Funds and Pension Funds. Hedge funds utilize OIS as a risk management tool against fluctuations in short-term interest rates that could impact their investment strategies. Pension funds, on the other hand, may employ OIS to align their assets and liabilities more effectively, thereby reducing their overall risk exposure.
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Central Banks. While not direct participants, central banks have an indirect influence on the OIS market. They exert control over short-term interest rates, which are often used as the floating rate in OIS contracts. The policies and decisions of central banks play a crucial role in shaping the broader market dynamics of OIS.
Risks Associated with Overnight Index Swaps
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Credit Risk. Despite being generally considered low-risk due to their short-term nature, OIS contracts are not immune to credit risk. This risk arises if one of the parties involved defaults on its obligations. The potential for default introduces an element of credit risk that participants must carefully consider and manage, even in the context of these short-term instruments.
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Market Risk. OIS contracts are sensitive to unexpected changes in overnight rates. Market risk emerges when there are unforeseen fluctuations in these rates, leading to potential losses for the party obligated to pay the floating rate. Participants in the OIS market need to be aware of the interest rate dynamics to effectively manage and mitigate market risk.
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Operational risk in OIS encompasses a range of potential issues related to the execution and management of these contracts. This includes risks associated with contract settlement processes, documentation errors, and system failures. Institutions engaging in OIS transactions must implement robust operational risk management processes to mitigate these potential pitfalls.
Example
Imagine a financial institution in the United States, XYZ Bank, that has several sizable floating-rate debt obligations. Concerned about the potential impact of rising interest rates on its interest payments, XYZ Bank decides to use an overnight index swap as a risk management tool.
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Initiating the Swap. XYZ Bank enters into a US OIS, which is an overnight indexed swap based on the Effective Federal Funds Rate (EFFR). EFFR represents the average interest rate that banks pay to borrow money from each other overnight in the United States.
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Execution. In this OIS, XYZ Bank agrees to notionally exchange the floating interest payments on its floating-rate debt obligations for fixed interest payments at a mutually agreed rate.
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Objective. The primary goal for XYZ Bank is to hedge against interest rate risk in the US overnight lending market. By doing so, the bank aims to fix its interest payments, allowing for more effective budgeting and protection against potential increases in interest rates.
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Result. If interest rates were to rise, XYZ Bank would be protected as it would be paid the difference between the fixed rate and EFFR, offsetting the increased cost of servicing its floating-rate obligations. This would allow XYZ Bank to manage its interest rate exposure more effectively.