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Option-Adjusted Spread (OAS)


Option-Adjusted Spread (OAS) is a measure used in fixed-income securities to represent the difference in yield between a security or bond and a risk-free rate, adjusted to take into account an embedded option. Essentially, it is the spread at which the present value of a security’s payments is equal to its price, excluding optionality. This allows investors to compare bonds with different maturities and yields on a level playing field.


Option-Adjusted Spread: /ˈɒpʃən-əˈdʒʌstɪd spred/

Key Takeaways

1. Measure of Risk and Yield: The Option-Adjusted Spread (OAS) is a widely used measurement of both the risk and estimated yield of a derivative security, specifically one with an embedded option, such as a callable bond. It quantifies the precise difference in yield between a derivative security and a benchmark risk-free security, thereby helping investors analyze the relative value of the derivative compared to risk-free securities.

2. Adjusts for Embedded Options: OAS is unique in its ability to adjust for the specific risk posed by embedded options. These options can vary widely in their terms and conditions, and can greatly influence the overall risk and return of a security. The OAS therefore gives investors a more accurate and comprehensive view of the risk and yield associated with a specific derivative security, beyond what simple measures like yield to maturity (YTM) can provide.

3. Useful in Complex Financial Analysis: The complexity of calculating OAS makes it most useful for sophisticated investors and analysts. It’s primarily used in the evaluation and comparison of various derivative securities, as well as in the construction and management of large security portfolios. Therefore, understanding and utilizing OAS can be crucial in performing complex financial analyses in highly volatile and uncertain market conditions.


The Option-Adjusted Spread (OAS) is a crucial measure in the financial world as it provides a more direct comparison of different types of bonds and securities. Since bonds often come with embedded options, these can affect the overall value and risk of the investment. The OAS adjusts for these options, isolating the credit or default risk of the bond and enabling investors to compare on a like-for-like basis. Thus, the OAS is an essential tool for identifying mispriced securities and making informed investment decisions, facilitating better risk management and contributing to successful portfolio performance.


Option-Adjusted Spread (OAS) plays a crucial role in the pricing and valuation of financial instruments with embedded options, such as mortgage-backed securities, and helps analysts and investors assess the relative value of these instruments. It fundamentally serves to evaluate the credit or default risk of a fixed-income investment that carries an embedded option. This measure allows a fair valuation comparison against other securities, as it adjusts the spread of the bond to account for the option embedded in it, thus capturing the risk specific to the instrument, independent of the option it carries.The use of OAS enables more accurate pricing and comparison of different securities. It accounts for the potential future changes in cash flows due to the embedded options, making it an indispensable tool for risk management and strategic asset allocation. Furthermore, OAS allows managers to consider the impact of yield volatility on option value and subsequently the price of the instrument. In essence, using OAS can help a potential investor to make a more informed decision about whether to invest in a particular bond or other fixed-income security by providing a more complete picture of that security’s risk and return characteristics.


1. Fannie Mae Bonds: Fannie Mae, a government-sponsored enterprise in the United States, regularly issues mortgage-backed securities. Analysts use the option-adjusted spread (OAS) to analyze these bonds and compare them to other securities without prepayment risk, like treasury securities. Effectively, the OAS helps to measure the difference in yield between Fannie Mae bonds and equivalent US Treasury securities after removing the effect of prepayment risk.2. Corporate Callable Bonds: A technology company can issue callable bonds to help finance a new product development. Callable bonds essentially grant the issuer – in this case, the technology company – the right to pay off their debt before maturity, if it suits their financing needs. Investors use the Option-Adjusted Spread to understand the value of the callable bonds after removing the value of the embedded call option.3. Adjustable Rate Mortgages (ARMs): In the banking sector, adjustable-rate mortgages are popular home loan products. The interest rates for these mortgages can fluctuate over time, meaning there is an element of uncertainty or risk for the lender (usually the bank) and the borrower. Lenders can use the OAS to help compensate for the risk arising from the potential for fluctuating interest rates – essentially, the OAS would help gauge what sort of premium they should charge over a risk-free rate to give them adequate compensation.

Frequently Asked Questions(FAQ)

What is Option-Adjusted Spread (OAS)?

The Option-Adjusted Spread (OAS) is a measure used to compare the yield of a security that comes with an embedded option (like a callable bond) to a benchmark security (like a treasury bond), which is risk-free. The spread reflects the additional yield required to compensate for the risks attached to the option.

How is OAS calculated?

The OAS can be calculated through complex financial modeling, such as the Monte Carlo model or the Black-Derman-Toy model. The formula includes inputs like interest rate volatility, the risk-free rate of return and the cash flows of the security.

Why is OAS considered important in finance?

OAS is crucial because it helps to expose the level of risk associated with securities that hold embedded options to provide a more precise picture of the expected performance, compared to other measures. It aids investors in deciding the right price for bonds with options.

What is the relationship between OAS and risks?

The higher the OAS, the greater the yield provided by the security to the investor to compensate for additional risks associated with the option. In other words, it represents the extra earning that an investor requires taking on the risk of the embedded option.

What is a positive OAS?

A positive OAS suggests that the security is providing a higher yield compared to the risk-free treasury security, essentially compensating for the additional risk associated with the embedded options.

Can OAS be negative?

Yes, OAS can be negative. A negative OAS might suggest that the security is overpriced or that the prevailing market interest rates are not likely to trigger the embedded option.

What securities is the OAS used for?

The OAS is commonly used for securities with embedded options like callable bonds, putable bonds, and mortgage-backed securities.

Can OAS help in investment decisions?

Absolutely. With OAS, investors can better evaluate securities with embedded options by separating the option risk from the interest rate risk, thus enabling them to make better-informed investment decisions.

Related Finance Terms

  • Yield Curve: A graphical representation that shows the interest rates on debt for a range of maturities.
  • Call Option: A financial contract that gives an investor the right, but not the obligation, to buy a certain amount of shares at a specified price before the contract expires.
  • Mortgage-Backed Securities (MBS): Investment products backed by mortgages, typically residential property loans. The income comes from the interest and principal payments made by borrowers on the underlying mortgages.
  • Interest Rate Risk: The risk that an investment’s value will change due to a change in the absolute level of interest rates or the spread of interest rates.
  • Credit Spread: The yield difference between bonds of similar maturities but different credit quality. It compensates investors for the additional risk of buying a bond with a lower credit rating compared to a safer government bond.

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