Wal-Mart has a long history as a titan of American retail. But in recent months, the company has been hit hard by fierce competition from smaller stores, online giant Amazon, and an uneven economic recovery that has been particularly sluggish for its key customers.

These challenges have been felt hardest by the global company’s most important market, its $279 billion U.S. division. For the past five quarters, U.S. same-store sales growth, which excludes stores opened or closed in the past year, had declined. U.S. stores have also reported a decline in foot traffic, another key indicator of a retailer’s health, for the past six straight quarters.

The latest sign of Wal-Mart’s struggles came on Thursday, when the company announced that it was replacing its U.S. chief. Bill Simon, who held the position for four years, will hand over the reins to Greg Foran, a company newcomer who has quickly risen through the ranks of Wal-Mart’s Asia business.

Industry analysts said they were not surprised by Simon’s departure after he was passed over last year for the retailer’s top job in favor of new company-wide chief executive Doug McMillon. They also cited the U.S. division’s recent financial woes as a likely factor in Simon’s departure.

“If you look at the Wal-Mart business, it’s not in great shape, and they’ve been pretty aggressive about replacing management and trying to replace the strategy,” said Scott Mushkin, a managing director at Wolfe Research. “If Wal-Mart’s U.S. business was doing well, this wouldn’t have happened.”

When he took over the U.S. division in mid-2010, Simon sought to right the retailer’s course amid the Wal-Mart’s worst-ever domestic slump. His renewed emphasis on consistently low prices and restoration of popular products helped the retailer show encouraging signs of growth in the second half of 2011 and into 2012. But Simon was unable to maintain those gains as the company’s U.S. division sunk into another slump in 2013.

William ” Bill” Simon, president and chief executive officer of Wal-Mart U.S., speaks during a news conference at the SelectUSA 2013 Investment Summit in Washington, D.C., U.S., on Thursday, Oct. 31, 2013. The summit is designed to connect investors with U.S. states and regions to explore business investment opportunities. Photographer: Andrew Harrer/Bloomberg *** Local Caption *** Bill Simon

Part of the challenge facing WalMart is the mounting threat from rivals both online and in traditional storefronts. Wal-Mart has seen its traditional market share eroded by ascendant dollar-chain stores, such as Dollar General, and Amazon, threats that the company has responded to by emphasizing smaller stores and revamping its online strategy.

Also, the retailer’s most reliable customer base, low-income consumers, were disproportionately affected by the recession and are recovering more slowly.

“[Wal-Mart is] very exposed to the low-end consumer, and that consumer has really suffered a lot,” said Faye Landes, a managing director at Cowen and Company.

Wal-Mart spokeswoman Brooke Buchanan declined to comment on whether the decision to replace Simon was motivated by the retailer’s recent disappointing financial performance, but acknowledged that the company saw room for improvement in its U.S. business.

“There’s no question that there’s opportunity for growth here in the U.S., and we are looking forward to Greg taking on his new position with all of his experience and passion for retail to serve our customers in every way possible,” Buchanan said.

The company’s stock is down about 3 percent this year, closing at $76.35 a share Thursday.

Foran has led Wal-Mart’s China division and, most recently, its Asia division since joining the company in 2011. In these roles, Foran presided over a region that faced regulatory challenges and the closure of a couple dozen underperforming stores in China this past winter.