Flash Crash (2010)
The Flash Crash of May 6, 2010 was a market event in which the Dow Jones Industrial Average plunged nearly 1,000 points in minutes before recovering almost as rapidly, exposing deep vulnerabilities in the structure of modern electronic markets.
At approximately 2:32 PM Eastern time on May 6, 2010, US equity markets entered one of the most bizarre episodes in their history. The Dow Jones Industrial Average, which had already been down roughly 300 points amid concerns about the Greek debt crisis, suddenly dropped an additional 600 points in the space of about five minutes, briefly touching a loss of nearly 1,000 points from the opening level before recovering almost as quickly as it had fallen. The entire episode, from the steepest decline to the partial recovery, lasted less than 30 minutes.
During the crash, shares of major companies briefly traded at prices that had no relationship to any rational valuation. Accenture, a large consulting firm, traded for $0.01 per share. Apple and other blue-chip stocks traded at prices hundreds of percent above their prevailing market values. These absurd quotes reflected the failure of electronic market-making systems rather than any real information.
A subsequent investigation by the SEC and CFTC identified a large sell order in E-mini S&P 500 futures contracts placed by a mutual fund as a triggering catalyst. The unusually aggressive execution of that order interacted with high-frequency trading algorithms in ways that amplified the selling pressure. As prices dropped, many automated market makers withdrew their liquidity or retreated from the market entirely, leaving a near-vacuum of buyers and allowing prices to move in extreme increments.
The Flash Crash accelerated regulatory attention on high-frequency trading and the fragmented structure of US equity markets. In the aftermath, regulators introduced updated circuit breaker rules — single-stock trading pauses that halt trading in an individual security if its price moves more than a specified percentage within a five-minute window. These replaced the market-wide circuit breakers introduced after Black Monday, which had been designed for much slower-moving market events.
The episode also demonstrated that technological complexity in financial markets could produce emergent behaviors that no individual participant anticipated or controlled. Subsequent flash crashes — including events in 2015 affecting the US Treasury market and in 2016 affecting the British pound — confirmed that the 2010 event was a symptom of structural issues rather than an isolated anomaly.