As a general rule, and one I actually manage to follow, I never look back on trades except to analyze them. It's one thing to look for what was wrong with the way you analyzed, traded, or passed upon an opportunity; it's another to simply regret making/not making a trade. Alas, there is one trade I fully regret--and I must come clean.
I was short BSC at $145, back during the summer. We were going into the numbers, and I was buying on anecdotal evidence about their PB acting--let's say--"off" with their hedge fund clients. I thought this was the beginning of the end. I shorted...heavy...for me.
Then I spoke to an analyst at one of the finest money-losing operations on the street--think Swiss--who was wildly bullish about their international operations. I hadn't done much dd on the investment, so I let him scare me off going into the numbers. I covered.
Mea Culpa, Friends.