Bull Market

A bull market is a sustained period of rising prices, most often defined as a broad index climbing 20% or more from its low without a comparable reversal. It reflects optimism about earnings, the economy, or both, and it feeds on itself: rising prices draw in more buyers, which pushes prices higher still.

Bull markets are the default state of US equities over long horizons. The S&P 500's bull runs have averaged multiple years and hundreds of percent in cumulative gains, which is why buy-and-hold investors are effectively betting that the next bull phase outlasts the next bear phase. The risk is complacency: the longer a bull market runs, the more investors extrapolate it forward as normal rather than as one phase of a cycle.