Walmart will lay off about 2,300 workers at its Sam's Club warehouse unit, The Wall Street Journal said, the latest in a string of job losses at US retailers. Half of the cuts will affect middle-management workers, the newspaper said, calling it "the club chain's biggest round of job cuts in four years." Walmart did not immediately confirm the numbers, which amount to about two percent of Sam's Club workers. "Over the years, we've migrated to a top-heavy structure in our management," said Sam's Club chief executive Rosalind Brewer, in an interview. "What this does is align the number of assistant managers to the sales of the club and to where our growth areas are." A range of major American retail groups, including JCPenney, Macy's and Target, have announced job cuts in recent weeks.