ASSETCASTING
MarketsEvent 2010.05.06

A fill does not protect the price: the 2010 Flash Crash

Abnormal executions during a plunge and recovery distinguish order execution from price control. Volume and narrow spreads did not reveal all the liquidity risk.

Updated Oct 21, 2026

Does avoiding a missed fill eliminate order risk?
Verified facts

Executions between a plunge and a recovery

On 2010-05-06, US indexes, stocks and ETFs fell sharply and recovered within a short period. The SEC chair’s contemporary congressional testimony described extreme executions and cancellation of some trades in 326 securities. The date identifies actual trading, not the later testimony.

Sources [1]
Verified facts

Risk hidden behind volume and tight spreads

A subsequent SEC staff explanation described a sharp decline in total E-mini buy-side depth that was not apparent from near-price liquidity and narrow spreads alone. Volume and spreads do not adequately describe liquidity in every situation.

Sources [2]
Concept

Execution priority and a price limit are different choices

Investor.gov explains that market orders do not guarantee the execution price, which may differ from the last trade. Limit orders fill only at the specified price or better, but may remain unfilled. Stop orders become market orders when triggered, so the stop price is not a guaranteed selling price.

Sources [3]
Interpretation

Execution discipline still leaves price risk

Questioning the habit of endlessly waiting for better quotes after deciding to trade differs from claiming execution at any price is always beneficial. The event separates intent, price limits and liquidity. Orders intended to avoid missed fills may still receive unexpected prices.

Sources [1][3]
Limitations

US intraday disruption differs from Korean closing auctions

A US intraday event is not a direct experiment on Korean closing call auctions. Rules, price limits, pauses and order conditions vary by market and period. This neither attributes every stock loss to order habits nor treats any order type as a universal return formula. It is source-based analysis, not personal experience.

Sources

  1. SEC Chair testimony: Examining the Causes and Lessons of the May 6th Market PlungeAccessed Oct 21, 2026
  2. SEC staff speech: Market Participants and the May 6 Flash CrashAccessed Oct 21, 2026
  3. Investor.gov: Types of OrdersAccessed Oct 21, 2026

Related learning notes

A liquidity squeeze sends rates higher, but the stock market’s spring may arrive soon | Park Se-ik, Chesley Investment Advisory [Newspaper review / 26.10.21, Wednesday]The video examines how waiting for a better quote can prevent execution of a trading decision. The Flash Crash supplies the complementary point that a filled order retains price risk. Examine missed-fill risk alongside price risk without treating a US intraday event as evidence of Korean closing-auction outcomes.