FAYETTEVILLE, Ark. – Walmart Stores Inc.’s CEO told shareholders Friday that the company is positioning itself for 20 years of worldwide growth and that it plans to hire 500,000 employees over the next five years.

The company also unveiled a $15 billion stock buyback. But it was short on specifics on how it will turn around weak business at its U.S. Walmart stores as the rest of the retail industry, including its key competitor Target Corp., has started to heat up.

But the recession is continuing to vex the world’s largest retailer as consumers keep a tight grip on their money.

“There is business opportunity in the world, but the world is changing fast in big, disruptive, complex ways,” CEO Mike Duke told shareholders packed into a University of Arkansas arena about 30 miles from its Bentonville headquarters.

A year ago, Walmart was in the sweet spot of the Great Recession. As shoppers traded down to cheaper stores, Walmart gained market share and saw big sales gains.

But now Walmart is struggling to hold onto customers. Its cash-strapped shoppers are looking elsewhere — such as dollar stores and local grocery chains — for even better deals than Wal-Mart offers. And some better-off customers, feeling more flush again, are heading back to the mall or Target.

Duke said Walmart must further tighten its expenses to keep its hallmark low prices lower than competitors. “We will win on price leadership,” he said.

Duke also noted that as retailing enters an era where shoppers can get deals anywhere and at anytime, it will push its low-price message more aggressively online and vowed it will focus more on mobile technology.

“Some of some of our competitors are ahead of us here. Building the best website will be just as important as getting our store formats right,” Duke said.

Following the formal presentations, Vice Chairman Eduardo Castro-Wright told reporters that stores in areas with high unemployment have the worst numbers while stores in low-unemployment areas are thriving.

Duke said Walmart’s global performance shows that there has been a worldwide recession for the last 18 months, and he didn’t predict improvement.

Duke said that company studies show Walmart shoppers are most worried about their income and keeping their jobs.

Accompanying the drop was an increase in how much customers spend. Shoppers still went to Wal-Mart to stock up, but midweek “fill-in” trips fell off, he said.