Bill Ackman says his fund has taken a new stake in Microsoft after the company's recent share price decline; Ackman says investors have underestimated Microsoft (Amy Thomson/Bloomberg)

Amy Thomson / Bloomberg: Bill Ackman says his fund has taken a new stake in Microsoft after the company's recent share price decline; Ackman says investors have underestimated Microsoft — Pershing Square Chief Executive Officer Bill Ackman said he's taken a new stake in Microsoft Corp. after a recent decline in the share price.