Mr. Market, a construct of the famous value investor Benjamin Graham, is a fickle individual. Sometimes he offers up opportunities that look attractively priced, only to change his mind far more quickly than you'd expect, running the price right back up again.When shopping for potential investments, I occasionally get access to the attractive price, which is what happened with my investment in WEC Energy (WEC -0.30%). But after the subsequent share price rally over just a few months, I decided to sell the u ...