The New York Times, which broke the story, reported that Wal-Mart officials, including Duke, were allegedly informed starting in 2005 about the bribes. McMillon was not linked to the incident because he wasn't working in the international division at the time.
Dave Tovar, a Wal-Mart spokesman, told The Associated Press that Duke's decision to leave Wal-Mart was "a personal one," and had nothing to do with the bribery allegations. "He decided it was time to retire," said Tovar, who added that Duke approached Walton and the board voted Friday.
Duke became CEO in February 2009 at a time when the retailer's strong performance made it the rare winner during the Great Recession. But that soon changed a few months after he took the helm.
As the economy slowly recovered, times got tough for Wal-Mart, resulting in a more than two-year slump in its U.S. namesake business. The company also made mistakes in pricing and merchandising that backfired.
During his tenure, Duke named a new U.S. executive team, which reversed the slump in the third quarter of 2011 by restocking thousands of items that had been ditched and pushing low prices across the store.
But those gains have been reversed since early this year. The U.S. Wal-Mart business has posted three straight quarterly declines in a key revenue metric. Wal-Mart also lowered its annual profit outlook twice in three months.
Duke will remain as chairman of the executive committee of the board. In the tradition of his predecessors, he will stay on as an advisor to McMillon for one year.
Meanwhile, the company said it plans to name McMillon's successor by the end of its fiscal year in early 2014.
Shares of Wal-Mart rose 63 cents to $80.44 in mid-day trading.
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