Volatility (σ)
how much the price bounces around · Risk & quality — durability and the shape of the bet
In plain English
How much a stock’s price swings, expressed as an annualized percentage and measured from real price history. ~20% is calm, ~60% is wild. It’s the raw material for the option models and half of the risk calculation.
The calculation
σ (annualized) = standard deviation of daily returns × √252
What each piece means
- standard deviation
- — the typical distance of a day’s return from its average
- √252
- — scales daily swings up to a yearly figure (~252 trading days/year)
Dig deeper
See it run on live stocks →Weekly Monitor computes this on ~1,000 names — free, in your browser, every formula shown. Nothing here is advice.