Portfolio Beta Calculator
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Holding a basket of individual stocks protects against company-specific risk, but it does not eliminate exposure to broader market swings. To determine how sensitive your overall investment portfolio is to benchmark index volatility (like the S&P 500), financial advisors measure Portfolio Beta (βₚ).
Our free Portfolio Beta Calculator computes the weighted average systematic risk of your entire multi-asset holding portfolio based on individual stock position weights and Beta coefficients.
How to Calculate Weighted Portfolio Beta
Portfolio Beta is calculated as the weighted sum of the individual Betas of all constituent holdings, weighted by their percentage share of total portfolio market value.
The Weighted Portfolio Beta Formula:
βₚ = ( w₁ × β₁ ) + ( w₂ × β₂ ) + ... + ( wₙ × βₙ )
Asset Weight Sub-Formula:
wᵢ = Market Value of Positionᵢ / Total Portfolio Market Value
- wᵢ: Portfolio weighting of stock i (expressed as a decimal fraction).
- βᵢ: Beta coefficient of stock i relative to the benchmark index.
Step-by-Step Portfolio Risk Example
Suppose an investor holds a $100,000 investment portfolio distributed across three distinct equity positions:
- Stock A (Tech Growth): $50,000 position (50.0% weight), Beta = 1.20
- Stock B (Utility/Defensive): $30,000 position (30.0% weight), Beta = 0.80
- Stock C (Cyclical Small-Cap): $20,000 position (20.0% weight), Beta = 1.50
Let’s calculate the weighted Beta contribution for each position and total Portfolio Beta:
Stock A Contribution = 0.50 × 1.20 = 0.600
Stock B Contribution = 0.30 × 0.80 = 0.240
Stock C Contribution = 0.20 × 1.50 = 0.300
Portfolio Beta (βₚ) = 0.600 + 0.240 + 0.300 = 1.14
| Portfolio Holding | Market Value | Portfolio Weight (wᵢ) | Individual Beta (βᵢ) | Weighted Contribution |
|---|---|---|---|---|
| Stock A (Growth) | $50,000 | 50.0% | 1.20 | 0.600 |
| Stock B (Defensive) | $30,000 | 30.0% | 0.80 | 0.240 |
| Stock C (Cyclical) | $20,000 | 20.0% | 1.50 | 0.300 |
| Total Portfolio | $100,000 | 100.0% | — | 1.14 Portfolio Beta |
Frequently Asked Questions (FAQ)
What does a Portfolio Beta of 1.14 mean for an investor?
A Portfolio Beta of 1.14 means your portfolio is theoretically 14% more volatile than the broad market benchmark (S&P 500). If the market rises by 10%, your portfolio is projected to gain 11.4%; if the market declines by 10%, your portfolio is projected to drop by 11.4%.
How can you reduce overall Portfolio Beta?
You can lower Portfolio Beta by allocating capital into low-Beta defensive assets (utilities, consumer staples), holding risk-free Treasury bonds (Beta ≈ 0), or allocating cash reserves (Beta = 0).
What is the Beta of cash in a portfolio?
Cash and money market funds have a Beta of 0.00 because their value does not fluctuate in response to stock market benchmark movements. Increasing cash allocation lowers overall Portfolio Beta.