Starbucks just poached the fast-casual chain's turnaround CEO. Shares of Chipotle Mexican Grill (CMG 0.32%) dropped 7% on Aug. 13 after the company announced the abrupt upcoming departure of its CEO, Brian Niccol, who had led the fast-casual restaurant chain since 2018. Niccol will take on the same role at Starbucks at the end of the month. That news stunned Chipotle's investors, since Niccol was credited with its digital-driven turnaround strategy over the past six years. Did the market overreact to the ne ...