Flash Crash 2010

On May 6, 2010, the US stock market experienced a sudden, dramatic collapse and recovery known as the Flash Crash. In approximately 36 minutes, the Dow Jones Industrial Average plunged nearly 1,000 points (about 9%), then recovered most of the loss within minutes. Individual stocks briefly traded at absurd prices — Accenture at $0.01, Apple at $100,000. Options were particularly affected, with many contracts executing at prices that bore no relationship to reality.

Why It Matters

The Flash Crash exposed the fragility of electronic markets and led to significant changes in market structure that affect options traders today. Circuit breakers, limit-up/limit-down bands, and clearly erroneous execution rules were all implemented or strengthened as a direct response. Understanding the Flash Crash helps you understand why these protections exist and how to protect yourself during sudden market dislocations.

For options traders, the Flash Crash demonstrated that market orders during periods of extreme stress can be filled at catastrophic prices. Limit orders are essential. The event also showed that options liquidity can vanish instantly, leaving traders unable to close positions at reasonable prices.

How It Works

What happened:

• At approximately 2:32 PM ET, a large institutional sell order (later traced to a mutual fund company) began executing a $4.1 billion sell program in S&P 500 E-mini futures
• The algorithm sold too aggressively, overwhelming available liquidity
• Prices began falling rapidly. High-frequency traders who normally provide liquidity pulled back.
• Selling cascaded from futures to stocks to ETFs to options
• Market makers in options withdrew their quotes or widened spreads to absurd levels
• Some stocks traded at $0.01, others at $100,000, as stop-loss orders and market orders triggered at extreme prices
• By 3:08 PM, prices had largely recovered. The entire episode lasted about 36 minutes.

Impact on options:

• Options on stocks that hit extreme prices were temporarily priced at extreme values
• Many options trades were later busted (cancelled) under clearly erroneous execution rules
• Some traders' stop-loss orders on options triggered at absurd prices and were not reversed
• Market maker withdrawal meant zero liquidity in thousands of options series

Regulatory changes after the Flash Crash:

• Single-stock circuit breakers: Pause trading in individual stocks that move more than a set percentage in 5 minutes
• Limit-up/limit-down (LULD): Prevents trades from executing outside price bands calculated from recent trading ranges
• Clearly erroneous execution rules: Formalized the process for busting trades at obviously wrong prices
• Market maker obligations: Strengthened requirements for market makers to maintain quotes during stress

Lessons for options traders:

• Never use market orders on options, especially during volatile periods
• Always set limit prices on your orders
• Be aware that stop-loss orders can trigger at extreme prices during flash events
• Understand that the trades you execute during a crash may be busted later
• Maintain wide mental stops rather than resting stop orders in the market

Quick Example

At 2:45 PM on May 6, 2010, you held 20 long call contracts on Accenture at $41. You had a stop-loss market order set at $38 to protect against losses. As Accenture's stock plummeted from $41 to $0.01 in minutes, your stop triggered and converted to a market sell order. Your calls were sold for $0.01 per contract in the absence of reasonable bids.

Minutes later, Accenture recovered to $40. Your calls were now worth approximately what you originally paid — but you had already sold them for pennies. Some of these trades were later busted by the exchange, but the process took days and not all trades were reversed.

If you had used a limit order (or no stop at all), you would have ridden the dip and recovered. The Flash Crash proved that resting stop-loss orders on options can be a trap during sudden market dislocations.