My worst trade's to date was "one day loser" of $14,000.00 + I was using Schwab StreetSmart and Scottrade at the time and I can't remember which account lost more, but the reason was that I was long two companies that reported earnings on the same day. At 4:01 PM the numbers came out and they both sold off one 20% and other 40% within minutes. If I would have been with CyberTrader or other broker with continuous trading at the time with no afters hours black-out period I would have been able to sell with some realized small gains. The big name brokerages are geared to steal your money for the sake of the street. Still pisses me off when I think about guys still in that trap.
In December 2003, I was short a shitload of live cattle. More than I normally traded. About 5 times my normal trade size... That night, I heard on the news "MAD COW IN WASHINGTON STATE".... I couldn't have been happier! This market would be limit down, and my thinking was (TOTALLY WRONG) that soy products would also get crushed.. So on the grain opening the next morning, I shorted an equal number of above average trading size in the soymeal market, which blasted higher, all but obliterating my trading gains in the cattle market, and then some...
I tell you how you DON'T. I tried to act like the loss didn't bother me and I jumped right back into another stock. Took a small loss, then did it again, then again, then again. I tried to tell myself that I wouldn't let that big loss bother me, but I was lying to myself. I should have been honest with myself and just backed away from the market until I had my head on straight again. If it ever happens again, that's exactly what I'll do, just go away for a few weeks at least.
got my ass handed to me trading size shorting otm index options a couple years ago. Took about a 70k hit on one trade. Never touched otm options since....
Company lowered guidance on Good Friday a couple years ago. I can't recall if earnings date was about 2 weeks before or coming up in about 2 weeks. My point being the news was right in the middle with no warning.
Bad news was the cause of one of my large losses in '04. I had sold a put (OTM) and in a week the stock tanked 20%...I ended up recovering as it was oversold.