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Glossary

Beta

Beta is a measure of how much an investment's returns tend to move relative to the overall market, indicating its sensitivity to broad market swings.

What Is Beta?

Beta is a statistical measure of how sensitive a stock, fund, or other asset is to movements in a broad market benchmark, such as a major stock index. It is a common measure of systematic risk, the portion of an investment's risk that cannot be removed through diversification. The market itself is assigned a beta of 1.0 as the reference point.

How Beta Is Calculated

Beta is usually estimated with regression analysis, which compares an asset's past returns with the returns of a benchmark over a set period, often several years of weekly or monthly data. The slope of the resulting line is the beta. It can also be expressed as:

Beta = Covariance(asset returns, market returns) / Variance(market returns)

Because beta is based on historical data, the result depends on the chosen time period, the measurement frequency, and the benchmark. Different data providers often report different betas for the same security for this reason.

Interpreting Beta Values

  • A beta of 1.0 suggests the asset has historically moved roughly in step with the market.
  • A beta above 1.0 suggests it has tended to move more than the market in both rising and falling periods.
  • A beta between 0 and 1.0 suggests it has tended to move less than the market.
  • A negative beta suggests it has tended to move in the opposite direction from the market, which is uncommon.

For example, if an asset has a beta of 1.5 and the benchmark rises 10 percent over a period, a simple model would expect the asset to rise about 15 percent, all else being equal. Actual returns rarely follow this pattern exactly.

Limitations and Role in Investing

Beta is backward-looking, and a company's sensitivity to the market can change as its business, debt levels, or industry evolve. Beta also says nothing about company-specific risk or whether an asset is expensive or cheap. It is a core input to the capital asset pricing model, which uses beta to estimate an expected return. Many investors also use it simply to gauge how much market-driven volatility a holding has historically added to a portfolio.

Updated October 15, 2026. For general education only; not financial, tax or legal advice.

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Related Terms

Diversification

Diversification is an investing approach that spreads money across different assets, sectors, or regions so that a poor result from one holding has a smaller effect on the whole portfolio.

Capital Asset Pricing Model (CAPM)

The Capital Asset Pricing Model is a formula that estimates the expected return on an investment by relating its risk, measured by beta, to the overall market's expected return and a risk-free rate.

Alpha

Alpha is the return an investment earns above what would be expected given its level of market risk, often used to judge whether a manager added value beyond a benchmark.

Unsystematic Risk

Unsystematic risk is the portion of an investment's risk that affects only a specific company or industry, such as a lawsuit or management change, and can be reduced through diversification.

Correlation

Correlation is a statistical measure of how closely two variables move together, expressed as a number from -1 to +1 that indicates the strength and direction of their relationship.

Volatility

Volatility is a statistical measure of how much and how quickly an asset's price moves up or down over a given period, with higher volatility indicating larger price swings.