Walmart announced Friday that its longtime CEO Doug McMillon will retire at the end of January — which came as a surprise to some given the company's success in a rapidly evolving retail landscape.

John Furner, the Walmart WMT -1.43% lifer who was named Doug McMillon’s successor as chief executive, has been leading the U.S. arm of the retail behemoth for several years.

Walmart begins its roll out of Black Friday events this Friday with deals on electronics and toys and everything in between.