Fidelity’s Contrafund, the biggest mutual fund investor in Chipotle Mexican Grill Inc, held steady in the company during the fourth quarter, even as an outbreak of food-borne illness in the restaurant chain pummeled its shares. “We held steady our investment in Chipotle, a longtime holding, deciding to hang in there, based in part on management’s focus on productivity and comparable-restaurant sales,” Contrafund portfolio manager Will Danoff said in his most recent commentary for investors.