Exclusive: Chipotle, Ackman talks intensify with confidentiality agreement

By Svea Herbst-Bayliss and Lisa Baertlein BOSTON/LOS ANGELES(Reuters) - Billionaire investor William Ackman and Chipotle Mexican Grill have signed an agreement to engage in confidential discussions, a source familiar with the matter said, in a sign that the activist may be able to force change at the burrito chain without a costly and drawn-out proxy contest. Ackman, who took a nearly 10 percent stake in the beleaguered fast casual food chain two months ago and has not disclosed his strategy, wa