Wal-Mart Stores Inc., the world's largest retailer, will buy back as much as $15 billion in shares and reduce the number of new stores as its chief executive, H. Lee Scott, responds to investor demands to boost returns.

The plan to buy back as much as 7.6 percent of Wal-Mart stock sent shares to their biggest gain in four years. Wal-Mart also said it will open no more than 200 supercenters this year, a reduction from the 270 it previously planned to create.

"Wal-Mart has taken a major step in attempting to improve returns on investment," Neil Currie, an analyst with UBS Securities LLC, wrote in a research note. He rates the shares "neutral 2."

Sales at its older U.S. stores in 2006 rose at their slowest pace in at least 27 years as Wal-Mart lost sales to Target Corp. Scott abandoned efforts to expand in Germany and South Korea and has disputed criticism of the company's wages and benefits from U.S. senators Hillary Clinton and John Edwards.

Scott, who has presided over a 27 percent decline in the stock during his seven-year tenure, continues to have the board's support, chairman Rob Walton said.

"The board and the Walton family have absolute confidence in your leadership, Lee," Walton said yesterday at the annual shareholders' meeting in Fayetteville, Ark.

Shares of Wal-Mart, based in Bentonville, climbed $1.87 or 4 percent, to close at $49.47 in composite trading on the New York Stock Exchange, the biggest gain since March 2003.

Capital spending will decline to $15.5 billion this year from a previous projection of $17 billion, the chief financial officer said.

Some of the supercenters that will open through the rest of this year will be relocated from existing sites while others will be expansions of discount stores, Wal-Mart said. About 80 of the supercenters scheduled to open in January 2008 will open later that year.

Square-footage growth in the U.S. will be as much as 5 percent this year and next, and 6 percent globally, the company said. In October, Wal-Mart had said U.S. square footage growth would be about 7 percent and that it would open between 265 and 270 stores.