We all have them. Barry Crockers, bloody shockers, trades we wish we had the TARDIS to correct.
What was yours?
Mine was the usual, in my early days of trading I thought I could predict the market - the fundamentals said that the EURJPY should rise. So I took a hugely over-leveraged position and blew my account. As it turned out Keynes was right when he stated that the market can be wrong for longer then I could stay solvent. My account was gone before the market did move in the direction I anticipated, but it was too late.
Luckily it was only a small, learning account of a couple of thousand, not fatal. It did learn me a huge lesson - it pushed me towards both technical and automated trading as well as better risk management.
What lesson did you learn from your mistake?