Yesterday’s post reminded me of another voice people often trust, but really shouldn’t: Wall Street analysts. A funny thing happened to one of the stocks in the Cabot Green Investor portfolio last month. The stock is American Superconductor (AMSC), a designer of wind turbines that also sells the electrical components for its designs. American Superconductor also makes highly conductive electrical wire for utilities. In late September, an analyst at Kaufman Brothers cut the stock from a rating of Buy to Hold. That sparked a wave of selling that pushed the stock from 37 to 30 in just four days....