Smith Collection / Gado / Getty Images Chipotle recently approved a plan to authorize buying back more of its stock. The latest limited-time offers at Chipotle? Carne asada—and, just maybe, its stock. Management at burrito giant Chipotle Mexican Grill (CMG) in a Monday regulatory filing said it was updating the company's buyback program ahead of schedule, announcing that on Sept. 3 it voted to approve a $500 million repurchase authorization that lifts its authorized amount to three quarters of a billion d ...