Volatility (VIX)

Volatility measures how much and how fast prices are moving, up or down, rather than which direction they're heading. The VIX is the most-quoted volatility measure, built from options prices on the S&P 500 to estimate how much swing traders expect over the next month. It tends to spike during genuine uncertainty, elections, geopolitical shocks, surprise data, and sit low during calm, steady periods. A "VIX spike" headline is shorthand for "traders suddenly expect a bumpy ride," regardless of whether that ride ends up going up or down.