Volatility

Volatility measures how much an asset's price swings around its average, usually expressed as the annualized standard deviation of returns. The S&P 500 has a long-run volatility around 15–20% per year; individual stocks are often 25–50%+. Higher volatility means wider swings — both up and down — and is the standard quantitative definition of investment risk. Lower volatility does not always mean lower return; many dividend ETFs (like SCHD) have historically matched index returns with lower volatility.