BENTONVILLE, Ark. — Walmart has made several changes in senior management, including a new chief executive officer for Sam’s Club and a new president and CEO for Walmart’s e-commerce business.

Walmart has made several changes in senior management, including a new chief executive officer for Sam’s Club and a new president and CEO for Walmart’s e-commerce business.

In addition, the company has promoted two executives to fill newly created positions — chief operating officer of its U.S. division and corporate chief administrative officer.

In a surprise move, Brian Cornell, president and CEO of Sam’s Club, told the company that he and his wife want to move back to the Northeast for family reasons. His replacement is Rosalind Brewer, who was president of the Walmart U.S. East business unit.

Cornell had overseen an impressive rebound at Sam’s Club since succeeding Doug McMillon as CEO of the division in 2009. McMillon now leads Walmart’s international division.

Walmart president and CEO Mike Duke paid tribute to Cornell’s performance. "Brian has done a terrific job at Sam’s Club," he said. "He is a strong, high-energy leader who has delivered great results and leaves behind a business with outstanding momentum. In addition to building a talented, high-functioning team to run that business, he has also developed other leaders who now hold senior positions around the globe."

As president of Walmart U.S. East, Brewer oversaw a business that generates more than $100 billion in annual revenue and has almost 1,600 stores and over 500,000 associates. In her new position she reports to Duke.

Before joining Walmart, Brewer worked for Kimberly-Clark, rising through various positions and eventually becoming president of a key business sector in 2004. She is a director for Lockheed Martin Corp. and was selected one of the Most Powerful Women in Business by Fortune magazine in 2010 and 2011.

"Roz came to us with an outstanding background in consumer packaged goods more than five years ago," Duke said. "During that time I have seen her develop into a talented merchant and retailer. She has strong strategic, analytical and operational skills, and has successfully managed a large and complex business. I’ve also been struck by Roz’s servant leadership when I have visited stores with her. She always lets her team do the talking, with her focus being on how to better support their needs."

Walmart has also named Neil Ashe, a former CBS executive with extensive online experience, as president and CEO of its global e-commerce unit. He succeeds vice chairman Eduardo Castro-Wright, who will retire in September.

At CBS Interactive, Ashe was in charge of the network’s online properties, with responsibility for developing new ways to distribute programming developed by CBS and its subsidiaries. Before that, he was CEO of CNET Networks, where he led the dramatic growth of its China division. During Ashe’s tenure at CNET, the company’s value rose to $1.8 billion from $100 million.

Ashe’s hiring underlines management’s intensified focus on expanding Walmart’s online business and developing its multichannel operations.

"E-commerce is a great opportunity for us, and we have a long-term vision to win," said Duke. "We are on track to create the next generation of e-commerce, combining the latest in online innovations with physical stores to give our customers a unique and seamless shopping experience."

In other moves, Gisel Ruiz, formerly executive vice president of people for Walmart U.S., has been promoted to executive vice president and COO of the flagship division. Also taking a newly created position is Rollin Ford, who has been promoted from chief information officer to chief administrative officer for the entire company. Replacing him is Karenann Terrell, who was assistant CIO for Walmart.

As COO for Walmart U.S., Ruiz will be responsible for the division’s operations, which includes more than 3,800 stores and includes Supercenters, discount stores, Neighborhood Markets and smaller formats. She will continue to report to Walmart U.S. president and CEO Bill Simon, and all three regional business unit presidents will report to her.

As Walmart’s chief administrative officer, Ford will oversee the information systems division, global sourcing, global business processes, global shared services and global customer insights. He will continue to report to Duke.