Portfolio Beta Calculator
Portfolio beta measures your portfolio's sensitivity to movements in the broad market. It is calculated as the weighted average of each holding's beta, where each weight is the holding's proportion of total portfolio value. A beta of 1.0 means your portfolio moves dollar-for-dollar with the market. Beta of 1.5 means your portfolio gains or loses 1.5% for every 1% market move. This calculator supports up to four holdings. Enter the current market value and beta for each, and the calculator computes the portfolio beta, letting you understand and manage your total market exposure.
Portfolio beta formula
Weight(i) = value(i) / total portfolio value
Portfolio beta = sum of (weight(i) * beta(i))
Each holding's weight is its share of total portfolio value. The portfolio beta is the sum of each weight multiplied by its beta. This assumes beta is additive across holdings, which holds under the Capital Asset Pricing Model (CAPM).
Using beta for risk management
- Beta of 1.0: matches market risk. Beta of 0.5: half the market's volatility. Beta of 2.0: twice the market's volatility.
- Low-beta assets (utilities, consumer staples, Treasury bonds) reduce portfolio beta.
- High-beta assets (technology, small-caps, emerging markets) increase portfolio beta.
- Beta only measures systematic (market) risk, not idiosyncratic (company-specific) risk. Diversification reduces idiosyncratic risk but not beta.
- Under CAPM, expected return = risk-free rate + beta * (market return - risk-free rate). Higher beta means higher expected return and higher risk.
Frequently asked questions
What is portfolio beta?
Portfolio beta measures how much the portfolio's value moves relative to the overall market. A beta of 1.0 means the portfolio moves in line with the market. Beta greater than 1.0 means amplified moves; less than 1.0 means dampened moves. Negative beta means it moves opposite the market.
How is portfolio beta calculated?
Portfolio beta is the weighted average of each holding's individual beta, where the weight is the holding's share of the total portfolio value. For example, a $60,000 holding with beta 1.2 in a $100,000 portfolio contributes 0.60 * 1.2 = 0.72 to portfolio beta.
Where can I find a stock's beta?
Beta is widely reported by financial data providers. It is calculated by regressing the stock's returns against a market index (typically the S&P 500) over 60 months. The SEC requires beta to be disclosed in risk factor sections of 10-K and prospectus filings.
What does a portfolio beta above 1.5 mean?
A portfolio beta above 1.5 indicates high market sensitivity. If the market falls 10%, such a portfolio would be expected to fall about 15%. This represents aggressive positioning and higher risk, appropriate only if the investor has high risk tolerance and a long time horizon.
How do I reduce portfolio beta?
Portfolio beta can be reduced by adding low-beta assets such as bonds, utilities, consumer staples, or inverse ETFs. Adding cash also reduces beta proportionally. Diversification across sectors that have low correlation with the market index lowers beta.
Official sources
- SEC: Investor Bulletin: Understanding Volatility.
- Federal Reserve FRED: S&P 500 Index Data.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.