Circuit Breaker: Level 1 and 2 market-wide circuit breakers suspend trading for 15-minutes and a level 3 halts trading for the rest of the day. This can happen when the S&P 500 falls more than 7% at any time before 3:45 p.m. EST.

Plunge protection: Turbulent markets can also be dampened by the purchase of huge quantities of stocks by large entities when prices drop. Big entities hold prices up to prevent individual traders from panic trading.

A stock market crash refers to a drastic, often unforeseen, drop in the stock market over a single or several days.

The sudden drop in stock prices may be influenced by economic conditions, catastrophic events, or speculative elements.