Wal-Mart Stores Inc.'s quarterly profit growth missed Wall Street's expectations on Tuesday, as the economy continues to weigh on customers at Walmart U.S., by far the company's largest division.

Still, key sales at those U.S. discount stores rose more than expected, reversing a string of nine quarterly declines.

Shares of Wal-Mart, the world's largest retailer, were down 1.8 percent at $57.93 in premarket trading.

Wal-Mart earned $3.34 billion, or 97 cents per share, from continuing operations in the third quarter ended on October 31, compared with $3.44 billion, or 95 cents per share, a year earlier. There were fewer shares outstanding during the most recent quarter.

The company had forecast a profit of 95 cents to $1.00 per share. Analysts on average expected 98 cents, according to Thomson Reuters I/B/E/S.

Every business segment is stronger today than it was a year ago, Chief Executive Officer Mike Duke said in a statement.

Sales momentum at Walmart U.S. and the Sam's Club warehouse chain position the company exceedingly well for the holidays, Duke added.

Net sales rose 8.2 percent to $109.5 billion.

Sales at U.S. discount stores open at least a year rose 1.3 percent. That topped the company's forecast, which called for Walmart U.S. same-store sales, excluding fuel, to be down 1 percent to up 1 percent. It also exceeded the analysts' average forecast for a rise of 0.3 percent, according to Thomson Reuters data.

Wal-Mart forecast fourth-quarter earnings of $1.42 to $1.48 per share from continuing operations, up from $1.41 a year earlier. That would lead to full-year earnings per share from continuing operations of $4.45 to $4.51, up from $4.18 last year.

(Reporting by Jessica Wohl in Chicago; Editing by Lisa Von Ahn)