Beta

What is Beta?

A measure of a stock's volatility relative to the overall market, where 1.0 moves in line with the market and higher values indicate larger price swings.

Overview

Beta is a measure of how much a stock's price tends to move relative to the overall market. A beta of 1.0 means the stock has historically moved in line with the market, a beta above 1.0 means larger swings, and a beta below 1.0 means smaller swings.

Beta captures systematic risk, the part of a stock's ups and downs that comes from broad market moves such as changes in interest rates, economic growth, or investor sentiment. It does not measure company-specific risk, such as a failed product launch, which can be reduced by holding a diversified portfolio.

Beta is a core input in the capital asset pricing model (CAPM), which uses it to estimate the return investors may require for holding a stock. In that model, the stock's risk premium over a risk-free asset is proportional to its beta.

Also Known As: Beta Coefficient, Market Beta, Equity Beta

Formula

Beta = Covariance(Stock Returns, Market Returns) ÷ Variance(Market Returns)

Equivalent form: Beta = Correlation × (Stock Standard Deviation ÷ Market Standard Deviation)

Formula Components:

Stock Returns: Periodic percentage price changes of the stock, often including dividends.
Market Returns: Returns of a benchmark index over the same periods. For US stocks this is usually the S&P 500.
Covariance: How much the stock and the market move together, in direction and size.
Variance: How much the market's returns spread around their average.

Common conventions: A widely used setup is five years of monthly returns (60 data points) against the S&P 500. Other providers use two years of weekly returns or one year of daily returns. Beta is also the slope of a regression line fitted through a scatter plot of stock returns against market returns.

On FinSpry: FinSpry does not calculate beta itself. Where a stock's statistics page shows beta, the value comes from market data, and the lookback window and benchmark depend on that source. Betas from different websites can differ for the same stock for this reason.

Calculation Example

Suppose five years of monthly returns for a hypothetical stock and its benchmark index give these statistics:

Monthly Return Statistics (60 Months):

Stock Standard Deviation	8.0%
Market Standard Deviation	4.0%
Correlation (Stock vs Market)	0.60

Step 1: Covariance and Variance

Covariance = 0.60 × 0.080 × 0.040 = 0.00192

Market variance = 0.040 × 0.040 = 0.0016

Step 2: Beta

Beta = 0.00192 ÷ 0.0016

= 1.20

Result: A beta of 1.20 means that, historically, the stock moved about 1.2 times as much as the market. When the market rose or fell 5% in a month, the stock tended to rise or fall about 6% on average. The correlation of 0.60 is a reminder that this is an average relationship, not a rule that holds every month.

Beta in CAPM:

Expected return = Risk-free rate + Beta × Market risk premium

With a 4% risk-free rate and a 5% market risk premium: 4% + 1.20 × 5% = 10%

The inputs here are illustrative assumptions. CAPM estimates are sensitive to every input, including beta.

How to Interpret

Beta is neither good nor bad on its own. It describes how sensitive a stock has been to market moves, which matters differently depending on an investor's goals and the rest of the portfolio.

Reading Beta Values:

Above 1.0

The stock has amplified market moves in both directions. Companies with cyclical sales, high operating leverage, or heavy debt often fall in this range.

About 1.0

The stock has tended to move with the market. A broad index fund tracking the benchmark has a beta close to 1.0 by construction.

Between 0 and 1.0

The stock has moved in the same direction as the market but by less. Businesses with steady demand, such as many utilities and consumer staples companies, often show lower betas.

Near Zero or Negative

A beta near zero means little relationship with the market. A negative beta means the asset has tended to move against the market, which is uncommon for individual stocks.

Beta Is Not Total Volatility:

A stock can be very volatile and still have a low beta if its swings are driven by company news rather than market moves. A biotech company awaiting a trial result is a typical example. To judge how much a stock can move overall, look at its standard deviation or price history as well as beta.

Limitations

Backward-looking: Beta describes past price behavior. A company that changes its business mix or takes on debt can behave differently in the future.
Depends on the setup: The lookback window, return frequency, and benchmark all change the result.
Unreliable for new or thinly traded stocks: Short price histories or infrequent trading make the estimate noisy.
Low correlation weakens it: When a stock's correlation with the market is low, beta explains little of its movement.
Symmetric by design: Beta treats up and down moves the same way, even though many stocks fall harder in sell-offs than they rise in rallies.

Related Financial Metrics

These concepts are often used alongside beta:

Risk Premium

The extra return investors expect for taking on risk; in CAPM it scales with beta.

Total Stock Return

Price change plus dividends, the kind of periodic return used to estimate beta.

Debt-to-Equity Ratio

Higher financial leverage tends to raise a company's equity beta.

Degree of Operating Leverage

High fixed costs make profits more sensitive to sales swings, which can show up as a higher beta.

Read more about total stock return, the debt-to-equity ratio, and the degree of operating leverage.

Use This Metric

Compare price performance across stocks in the screener to see which ones have moved more or less than the market.

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