Steinhafel has been working at Target for 35 years and had been serving as the company’s CEO since 2008. Under Steinhafel’s watch, Target was the victim of a data breach that was first disclosed on Dec. 19, 2013. The breach occurred between Nov. 27 and Dec. 15, 2013, and impacted at least 70 million consumers. John Mulligan, Target's chief financial officer, will act as the interim president and CEO, and Steinhafel will work as an adviser to the company during the transition period.