By Svea Herbst-Bayliss and Emily Flitter BOSTON/NEW YORK (Reuters) – In the past, billionaire investor Daniel Loeb would often wait for an industry conference before revealing his investment ideas. The hedge fund manager and some other prominent investors have now turned to Harvest Exchange, a new website designed for investors, to release news of their big bets. Such announcements — including Loebs bet on Dow Chemicals and Kyle Bass bet on General Motors — often lead to big swings in share prices as other investors pile on.