How about when you think you're long but you're actually short. You don't realize your mistake for a while and its ends up being a fairly decent trade.
I was short via Rydex 2x inverse S&P funds from early Sept 2002 into the bottom October and I gave back 90% of my paper profits because I didn't think the bottom was in.....it was.....
Not a trading story, but: When I was younger I used to drive a motorcycle and I also smoked. One night it was late and I'd been riding for awhile and I was tired so I decided to pull over to the side of the road and have a smoke. As I was relaxing w/my cigarette I got curious as to how much gas I had. So I took the cap off the tank and actually lit a match, intending to put it into the mouth of the tank to check the gas level. Then I realized what I was about to do. It still gives me the willies 20 yrs later to think that I was about to pull some kind of grotesque 3 Stooges routine. H
Sending a large basket of orders after entering the price of S&P futures out by 100 points. I was long about $10M worth of stock before I could cancel the rest. Got freakin' lucky with the market and actually made a few grand, but could have wiped out my account.
My top two: 1) Trying to short the market from March to June 2003 !! 2) Signing up for EWI services - the ultimate newbie mistake. Utter bollocks. Cheers J
Moving the suburbs from the gold coast in chicago, then trying to trade from home alone instead of in an office environment.