NEW YORK, May 15 : Two of Wall Street's most closely watched billionaire stock pickers, both once voluble activist investors, took opposite tacks this year when Bill Ackman bet on Microsoft and exited Google parent Alphabet and Daniel Loeb did the opposite. Ackman said on X his firm Pershing Square began building a new position in software giant Microsoft in February after shares dropped, saying investors weren't giving it enough credit for its Microsoft 365 office suite and artificial