These big brokers like UBS and GS are all in this together.. One day GS upgrades and the next UBC downgrades and on and on. When one downgrades they all buy on the cheap and after an upgrade they sell.
As long as they pick volatile stocks, they can trade: buy, sell, go short, do the whole option enchillada...while the rest of us just sit and watch...and get whipped around like a bunch of clueless idiots. That's why a guy like Buffet has done pretty well. He knows what he owns, and really rarely trades.
I one knew a smart pro who said: Wall Street loves to make pennies but doesn't know how to make dollars.