April 25 (Reuters) - Walmart ( WMT ) said on Thursday

that Rob Walton would retire from the board of the big-box

retailer at the end of his term on June 5.

Walton, the eldest son of Walmart ( WMT ) founder Sam Walton, served

as the company's chairman of the board of directors from 1992 to

2015, according to a bio on the company's website.

After joining the company in 1969, Walton held several

roles, including senior vice president, corporate secretary,

general counsel and vice chairman.

"His leadership has been critical as we've grown our

business over so many years," Greg Penner, the current Chairman

of Walmart's ( WMT ) board said in a regulatory filing announcing

Walton's retirement.

The Walton family is the richest family in America,

according to Forbes, thanks to their stake in the retailer, the

world's largest by sales.