Google is a buy, but investors might want to wait until after earnings

Shareholders in Google (GOOG) know all too well the heartbreak of high expectations. When the world's dominant Internet search company reports earnings after Thursday's close, it had better beat Wall Street estimates -- and beat by a lot.

That's because Google is a momentum stock, where investors pay a fat premium for shares based on accelerating top-line growth, which is then supposed to flow to the bottom line. It's always risky for retail investors to fiddle around with stocks during reporting season, especially when the company in question doesn't provide any earnings guidance -- and historically needs to beat Wall Street estimates by a wide margin to get any love.