On May 6, 2010, the Dow Jones Industrial Average fell nearly 1,000 points — 9.2% — in 36 minutes, then recovered almost entirely within minutes. Procter & Gamble briefly traded at $0.01. Accenture fell from $40 to $0.01. The 2010 Flash Crash exposed the fragility of algorithmic trading systems and the dangers of a market structure dominated by high-frequency traders.
The Trigger: A Single Large Sell Order
The SEC's investigation identified the trigger: a mutual fund company (later identified as Waddell & Reed) executed a large sell order of 75,000 E-Mini S&P 500 futures contracts worth $4.1 billion using an automated algorithm that executed based on volume, not price.
As the algorithm sold, prices fell. As prices fell, high-frequency traders — who provide liquidity in normal conditions — withdrew from the market. With liquidity gone, the algorithm's continued selling caused prices to collapse.
The Cascade: How HFTs Made It Worse
High-frequency trading firms are the modern equivalent of market makers — they provide liquidity by continuously posting buy and sell orders. In normal conditions, this liquidity is beneficial. In the Flash Crash, HFTs detected abnormal conditions and withdrew their orders simultaneously.
With HFTs gone, the market became illiquid. Individual stocks traded at absurd prices: Procter & Gamble at $0.01, Accenture at $0.01, Apple at $100,000. These were clearly erroneous trades, but they happened because there were no buyers at any reasonable price.
The Recovery and Regulatory Response
The market recovered almost entirely within 20 minutes of the bottom. The SEC and CFTC cancelled trades that occurred at prices more than 60% away from the pre-crash price. New circuit breakers were implemented for individual stocks — halting trading for five minutes when a stock moves more than 10% in five minutes.
The Flash Crash accelerated regulatory scrutiny of high-frequency trading. The SEC introduced new rules requiring HFTs to maintain their market-making obligations during volatile conditions — though enforcement has been challenging.
Flash Crashes Since 2010: A Recurring Phenomenon
The 2010 Flash Crash was not a one-off. Similar events have occurred repeatedly: the 2015 Chinese stock market crash, the 2016 British pound flash crash (fell 6% in two minutes), the 2018 VIX spike, and numerous individual stock flash crashes.
For traders, flash crashes create both danger and opportunity. Danger: stop losses can be triggered at absurd prices during the crash. Opportunity: the rapid recovery often creates excellent entry points for those who can act quickly. Capitals.au AI monitors order flow anomalies that precede flash crash conditions.
✅ Key Takeaways
- The Dow fell 9.2% in 36 minutes on May 6, 2010, then recovered almost entirely
- A single $4.1B sell order triggered the cascade by overwhelming HFT liquidity
- HFTs withdrew simultaneously, removing all liquidity from the market
- Individual stocks traded at $0.01 — clearly erroneous prices with no buyers
- New circuit breakers for individual stocks were implemented after the Flash Crash
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