Wal-Mart Stores Inc named company veteran Doug McMillon to replace Chief Executive Mike Duke, who will retire on January 31 after five years at the helm of the world's largest retailer.

McMillon, 47, is currently CEO of Wal-Mart's international division. He will start in his new role on February 1, the company said in a statement on Monday.

McMillon was promoted to his current role as head of the company's second-largest operating unit in January 2009. Prior to that, he was president and CEO of Sam's Club.

"McMillon was responsible for the growth area for Wal-Mart - international sales - and that's why he got the nod," said Walter Loeb, president of retail consultancy Loeb Associates.

Wal-Mart, whose shares were little changed before the bell, has struggled to find traction in the United States, with its comparable sales frequently missing Wall Street estimates.

The retailer has faced intense competition from dollar stores and other discounters such as Target Corp .

Comparable sales in the United States fell for the third straight quarter last quarter. International sales rose 4.1 percent, excluding the effect of currency fluctuations.

During Duke's five-year tenure as chief executive, Wal-Mart's share price has risen by just over half, underperforming a more-than doubling of the S&P 500.

Duke, 63, will continue as chairman of the executive committee of the board and stay on as an adviser to McMillon for a year. Duke will be paid $1.1 million for the year to January 31, 2015, Wal-Mart said in a regulatory filing.

Wal-Mart shares were trading at $79.96 before the bell.

(Reporting by Aditi Shrivastava in Bangalore and Phil Wahba in New York; Editing by Joyjeet Das and Ted Kerr)