Which 2010 U.S. market event briefly erased nearly $1 trillion in equity value within minutes?

The 2010 U.S. market event that briefly erased nearly $1 trillion in equity value within minutes was the 2010 Flash Crash.

On May 6, 2010, major U.S. stock indexes suddenly fell and then recovered much of the loss. The Dow Jones Industrial Average dropped about 1,000 points, or nearly 9%, during the session. Some individual securities traded at implausible prices before markets stabilized.

Investigations found that high-frequency trading, market fragmentation, automated selling, and rapidly changing liquidity interacted in unusual ways. The event was not a conventional, weeks-long bear market. Instead, computer-driven orders and the withdrawal of available buyers amplified a very fast decline.

The crash led regulators and exchanges to introduce safeguards, including circuit breakers and rules for handling clearly erroneous trades. A common mix-up is the 1987 crash, which was a separate global market collapse. The 2010 event is especially associated with electronic trading and market microstructure.