Kroger Chief Executive Rodney McMullen resigned from the company following a board investigation into his personal conduct, ending a more than four-decade career at the grocery chain.Kroger, the biggest U.

Under his leadership, Kroger has positioned itself as a formidable competitor to Walmart, Amazon, and other grocery giants.

Here's what you should know about Kroger CEO Rodney McMullen, who resigned following "a board investigation of his personal conduct."