NEW YORK (Bloomberg) Wal-Mart Stores Inc., the largest private employer in the US, plans to stop paying staff there an additional $1 an hour for working Sundays, taking a bite out of its single biggest expense.

The move, which takes effect next year, applies only to employees hired after January 1, spokesman Greg Rossiter said in an interview today. The move wouldn’t affect the Bentonville, Arkansas-based retailer’s 1.4 million current US staff.

Since taking over almost two years ago, CEO Mike Duke has pledged to slow cost growth as the retailer copes with six straight quarters of sales declines at US stores open at least a year. Operating expenses rose to about $80 billion last year, partly because of health benefits.

“It’s sad people who work on Sunday need that extra dollar,” Cynthia Murray, a Wal-Mart employee at a supercenter in Laurel, Maryland, said in an interview. Murray said she makes $11.20 an hour, and doesn’t work Sundays.

The move won’t apply to employees based in Rhode Island and Massachusetts, who weren’t eligible for the extra pay owing to state employment laws, Rossiter said. The retailer has 49 stores in Massachusetts and 10 in Rhode Island as of this month, according to its website. The change will take effect at Wal-Mart stores, Sam’s Club outlets and warehouses. The decision represents a blow to hourly workers, said Dorian Warren, an assistant professor of international and public affairs at Columbia University who studies labour relations.