Volatility and Beta: How to Measure Stock Risk
Understand volatility and beta to evaluate the risk of your investments. Practical guide with concrete examples and strategies adapted to your profile.
· 5 min read
Risk is the counterpart of returns. No risk, no gain. But understanding and measuring that risk is essential to not lose your shirt.
This article is part of our Complete Guide: How to Analyze a Stock
Part 1: Volatility
What is Volatility?
Volatility measures the amplitude of price variations of a stock. The more prices move, the higher the volatility.
Simplified formula:
Volatility = Standard deviation of daily returns × √252(252 = trading days per year)
Risk Classification
| Annualized Volatility | Risk Level | Examples |
|---|---|---|
| < 15% | Low | Utilities, Consumer staples |
| 15-25% | Moderate | Large caps, Blue chips |
| 25-40% | High | Tech, Biotech |
| > 40% | Very high | Small caps, Crypto |
Implied vs Historical Volatility
- Historical volatility: Calculated from past prices
- Implied volatility: Derived from options, reflects expectations
When implied volatility > historical = Market anticipates turbulence.
Part 2: Beta
What is Beta?
Beta measures a stock's sensitivity to market movements.
Beta = Covariance(Stock, Market) / Variance(Market)Interpretation:
| Beta | Behavior |
|---|---|
| < 0 | Inverse movement to market (rare, e.g., gold) |
| = 0 | Independent of market |
| = 0.5 | Moves 2x less than market |
| = 1 | Follows market exactly |
| = 1.5 | Moves 50% more than market |
| = 2 | Moves 2x more than market |
Real Examples
| Stock | Beta | Behavior |
|---|---|---|
| JNJ | ~0.6 | Defensive, stable |
| KO | ~0.6 | Crisis resistant |
| AAPL | ~1.2 | Slightly more volatile |
| NVDA | ~1.7 | Amplifies movements |
| TSLA | ~2.0 | Very reactive to market |
Strategies Based on Your Profile
Conservative Profile
- Goal: Preserve capital
- Target beta: < 0.8
- Volatility: < 20%
- Stock types: JNJ, PG, KO, Utilities
Moderate Profile
- Goal: Steady growth
- Target beta: 0.8 - 1.2
- Volatility: 20-30%
- Stock types: AAPL, MSFT, JPM
Aggressive Profile
- Goal: Maximum performance
- Target beta: > 1.2
- Volatility: > 30%
- Stock types: NVDA, TSLA, AMD, SHOP
Practical Application
Calculate Your Portfolio Risk
- List your positions with their weight (%)
- Get the beta of each stock
- Calculate weighted beta of portfolio
Example:
| Stock | Weight | Beta | Weighted Beta |
|---|---|---|---|
| AAPL | 30% | 1.2 | 0.36 |
| MSFT | 30% | 1.1 | 0.33 |
| JNJ | 20% | 0.6 | 0.12 |
| KO | 20% | 0.6 | 0.12 |
| Total | 100% | 0.93 |
Result: Portfolio slightly less volatile than market
Watch Out for Correlations
A portfolio with 5 tech stocks at beta 1.5 is not diversified. They'll all move together.
Solution: Our correlation matrix shows links between your positions.
VaR: Value at Risk
VaR answers: "What's my maximum probable loss over X days with Y% confidence?"
Example:
- Portfolio: $100,000
- 1-day VaR at 95% = $2,500
In 95% of cases, you won't lose more than $2,500 in one day.
Tools to Measure Risk
Portfolio Terminal
Our tool automatically calculates:
- Volatility of each position
- Portfolio beta
- Correlation matrix
- Sharpe Ratio
Conclusion
Risk management is as important as stock selection.
Remember:
- Volatility measures movement amplitude
- Beta measures market sensitivity
- Adapt exposure to your profile
- Diversify with low correlations
Also read: Complete Guide: How to Analyze a Stock in 2026
Check our stock analyses to see volatility and beta of 443 stocks, ETFs and other assets.
#risk-management#volatility#beta#analysis
Part of
cite: Julien Esnault, “Volatility and Beta: How to Measure Stock Risk”, Portfolio Terminal, 2026-01-29. plain-text version for AI tools
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