Compute annualized volatility as daily volatility times the square root of 252.
年化波动率 = 日波动率 × √交易日数。
| Item | Formula / Rule | Source / Standard |
|---|---|---|
| Daily return basis | Daily volatility is the sample standard deviation of daily returns, normally log returns | Hull 2022, Options, Futures and Other Derivatives, Ch. 15 |
| Square-root scaling | Multiply by √252 to annualise and divide by √252 to recover the daily figure | Hull 2022, Options, Futures and Other Derivatives, Ch. 15 |
| Assumption limits | With autocorrelation or volatility clustering the square-root rule misstates annualised volatility | Jorion 2007, Value at Risk, Ch. 4 |