Walmart said that Brian Cornell is stepping down as chief executive of Sam’s Club. Cornell cited personal reasons for the decision to leave. From February 1, he will be replaced by Rosalind Brewer who most recently served as president of the Walmart US east business unit. Walmart disclosed several other key executive changes including Rollin Ford, who has been promoted to chief administrative officer, Karenann Terrell is to be chief information officer and Gisel Ruiz is the new chief operating officer for Walmart US.