(Reuters) -Kroger ( KR ) said on Monday Chief Executive Officer Rodney McMullen has resigned from the post after a board investigation found that his personal conduct was inconsistent with the grocer's "policy on business ethics".

The move comes a few months after Kroger ( KR ) terminated its $25 billion merger plan for Albertsons, with the latter suing its rival and alleging a breach of contract that led to the deal's demise. Kroger's ( KR ) shares were down 1% before the bell.

On February 21, the board was made aware of certain personal conduct by McMullen and immediately retained outside independent counsel to conduct an investigation, which was overseen by a special board committee, according to the company.

McMullen's conduct is not related to the company's financial performance, operations or reporting, and it did not involve any Kroger ( KR ) associates, it said.

The board has appointed lead director Ronald Sargent as interim CEO, effective immediately. Mark Sutton will be Kroger's ( KR ) lead independent director.

The company is scheduled to report its fourth-quarter results on Thursday.