I think there is an air of invincibility about the investment...

I think there is an air of invincibility about the investment banks and their analysts - usually because of the prestige of the companies, their alumni in government and the Fed etc. and their analysts seeming to come from "superstar" universities like Oxbridge, Harvard, LSE etc. (even to some degree in Australia) - however the success rates of their predictions are surprisingly woeful and some of their analysis is a bit questionable. Despite that all it takes is a broker downgrade to send an already out of favour stock plummeting - there have been lots of examples of this.