The plunge protection team prevented a real crash: http://en.wikipedia.org/wiki/Working_Group_on_Financial_Markets
The real reason for this drop was a completed Elliot wave structure coming into a Sam Seiden supply/demand zone on a daily chart. When this happens...watch out !!:eek:
After this incident, my confidence in world's biggest futures markets has gone down. There is no reason next time we have a flash crash (either RTH or in globex session) ES doesn't fall say 300 points. This means if your broker auto-liquidates you then any margin below 15000 USD will ensure that you blow up. Doesn't matter if you trade a 10k account or a 500k account. It will just mean a blowup. So, if you are retail and trade mostly 2-3 products (not like CTAs who can have 20 positions simultaneously), most likely it will mean a blowup for you - if you don't have a stop. So, to avoid this situation - one key takeaway is to always have a stop - it can be 10 points or 30 points, but always & under every circumstances have a stop. Even if backtesting shows that (lets say) having a 10 point stop degrade performance, then have a 20 point stop, but always have a stop. Better to accept a little bit degraded performance than being left with an account blowup.
It's impossible for ES to fall 300 points in a single session; it's limited to 5% overnight and 10% from pclose during RTH. Theoretically it could be pinned at limit down then go limit down again the next day, but that wouldn't be a 'flash crash.'
During RTH, the price limits are 10%, then 20%, then 30% all on the downside only. For extended hours, the limit is 5% both up and down. So yeah, a 300 point AH drop in the ES is pure fantasy. I saw that post earlier and chuckled. Sometimes it's good to let people keep their fantasies.
http://finance.yahoo.com/q/ta?s=^IXIC&t=5y&l=on&z=l&q=l&p=&a=&c= Look a little before Jan 2009 on the Nasdaq. This is when the market went down, and never came back up. Now, I am not saying that it happened in one day, but if you did not have a stop, and kept waiting for bounce or averaged down to get a bounce, you would have been wiped out. However, if you were Buffet and not on margin, you could in fact buy some stocks and make some money like he did.