What Is How to Calculate and Control Portfolio Volatility?
Portfolio volatility is calculated as the standard deviation of portfolio returns, incorporating both individual asset volatilities and their pairwise correlations. The formula shows that low correlations between holdings dramatically reduce overall portfolio volatility.
Why It Matters
A portfolio of 10 stocks each with 30% volatility but 0.3 average correlation will have portfolio volatility of approximately 17%. The same 10 stocks with 0.7 correlation would produce 25% portfolio volatility — nearly 50% higher risk for the same holdings.
How LyraIQ Approaches This
LyraIQ's volatility calculator computes standard deviation, downside deviation, and conditional volatility for your portfolio. The system identifies which holdings contribute most to volatility through marginal contribution analysis and suggests lower-volatility alternatives with similar expected returns.
Practical Steps
- Calculate individual volatilities for each holding
- Estimate pairwise correlations using 1-year historical data
- Compute portfolio volatility using the variance-covariance matrix
- Identify the 3 holdings with highest marginal volatility contribution
- Replace or reduce high-volatility holdings with lower-beta alternatives