A bear market is a term used by Wall Street when an index such as the S & P 500 or the Dow Jones Industrial Average has fallen 20% or more from a recent high for a sustained period of time.

Wall Street's main indexes fell hard again on Thursday on concerns over the impact of high tariffs on the global economy, marking a U-turn from the previous session's historic share gains when U.S. President Donald Trump moved to temporarily lower the levies on some countries.