I have traded thru several "fat finger" events, all in my favor or I was idle by pure random chance. One ER trade went -15pts down and +15pts back up in less than five minute's time. I was short and caught most of that drop, also by random chance. Had stepped away from the screens to cook lunch, took a quick peek in the office (off kitchen) and saw prices off the charts.
Had I been long, stops would have slipped several points.
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Got blown out of a ZB trade for one full point against me on some Greenspan utterance back in late 2003.
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Traded thru two surprise interest rate cuts, Jan 2001 and Apr 2001. Got pounded on long OEX puts first time, bought SPX calls literally minutes before the second event when noticing 1,000s of atm and slightly otm front-month SPX call options clearing.
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Was long five SPX puts, about to close them for net loss on 9/11 morning. Bought them for $1,700 each and they opened at $8,000 each following week, just before expiry would have made them worthless.
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I know a trader who lost $1mil in the bond pit during first Iraq war invasion, 1991. Futures prices were trading 1.5 full points wide in the pit as news broke.
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Eventually we will see something happen to shock the markets. Act of war, assassination of key leader, environmental disaster to hit key city like L.A. or NY, London, Tokyo, etc
Bottom line is, never trust your presence in a chair OR stop orders resting in the system to exit in timely fashion every time. Always trade with ability to withstand extreme slippage against your position, and everything will be fine.