Stock prices may change suddenly due to unexpected crises or new information reaching the market.

Stocks rising and falling is an everyday occurrence but when a market mover drags down an entire sector—and sometimes the entire market—people take notice. A company can post negative earnings with unattractive future rhetoric as $Meta Platforms(META.US)$ did, causing them to lose hundreds of billions or a company can surprise on the upside, such as with Gateway and the surprise acquisition that sent its shares soaring.