several years back i was day trading MEDI (medimune) the company that developed the flu mist. I was heavily loaded up with it and thought i closed my position when in fact i doubled it. Later that night i checked my trades and couldn't believe how stupid i was. I am mostly a day trader so I was a bit pissed off at my mistake. the next day the stock gapped up over $3.00 per share It was one of the most profitable trades i have made. It could have easily gone the other way. It was dumb luck.