gregg steinhafelTarget CEO Gregg Steinhafel has stepped down in the aftermath of the massive data breach late last year.

"Today we are announcing that, after extensive discussions, the board and Gregg Steinhafel have decided that now is the right time for new leadership at Target," said a statement today from the Minneapolis retailer.

The data of 40 million Target customers was exposed in the breach, one of the worst in corporate history. The company last week outlined security enhancements and named a new chief information officer in response.

Target today also released Steinhafel's letter of resignation. "The last several months have tested Target in unprecedented ways," he said, adding, "With several key milestones behind us, now is the right time for new leadership at Target."

The board praised Steinhafel's work following the breach. "He held himself personally accountable and pledged that Target would emerge a better company," the board said.

CFO John Milligan was named interim president and CEO, while board member Roxanne Austin is non-executive chair.

Target has more than 1,900 stores in the US and Canada.