Stocks ended the session higher Monday after falling oil prices and a strong performance by semiconductor shares extended a market rally that began last week.

The Dow Jones industrial average ended higher 23.89 points, or 0.23 percent, to close at 10,216.54. The technology-laced Nasdaq Composite Index rose 10.20 points, or 0.53 percent, to end at 1,952.40, while the Standard & Poor's 500 index was higher 3.67 points, or 0.32 percent, to close at 1,135.17.

Oil prices eased on Monday after rebels in Nigeria withdrew a threat to target oil operations, but lingering concerns over stretched supplies ahead of winter kept prices close to $50 a barrel.

Semiconductor shares also helped stocks up Monday. National Semiconductor Corp. (NSM), a maker of chips that manage power consumption in electronics, gained 2.6 percent to $16.75 after it said on Friday it would begin paying a quarterly dividend.

Intel Corp. (INTC), another chip stock, rose 1.3 percent to $21.13, helping to lift the Dow and the Nasdaq.

Siebel Systems Inc. (SEBL) rose 14 percent after the business software company said it expects third-quarter revenue above Wall Street expectations. Siebel jumped $1.15 to $9.34, lifting the Standard & Poor's 500 and the Nasdaq.

"Today we are seeing follow-through from Friday's lift and the news from Siebel has helped to continue buying interest in technology stocks," Paul Cherney, chief market analyst at Standard & Poor's. On Friday, the Nasdaq hit a three-month high, while the Dow closed up 112 points.

"Also, the price of crude has been weaker," Cherney said.

Stocks received a boost before the session opened when Philadelphia Federal Reserve President Anthony Santomero said in a speech he expected the economy to grow by 3.5 percent to 4 percent through 2005. Combined with the buying that customarily opens a new quarter, stocks were poised for another day of gains, although recent economic data and the forecast for third-quarter earnings may not support the bullishness.

American Express Co. (AXP) rose after the Supreme Court let stand a ruling that Visa and MasterCard credit card associations violated U.S. antitrust law by barring member banks from issuing credit and charge cards on rival networks owned by American Express and Morgan Stanley (MWD).

American Express shares climbed 2 percent to $52.63, helping the blue-chip Dow.

In corporate news, Wal-Mart Stores Inc. (WMT), a closely watched bellwether for the retail sector, pleased investors as it announced that sales at its stores open at least a year rose 2.3 percent in September, somewhat making up for a disappointing August. While sales fell compared to a year ago, investors saw the increase as a plus, especially considering the recent lack of consumer spending. The company also approved an additional $3 billion stock buyback program, adding to a $7 billion program previously announced. Wal-Mart rose 18 cents to $53.31 on the NYSE.

Dow component American International Group Inc. (AIG), one of the world's largest insurance firms, slipped 23 cents to $68.49 after it announced the Securities and Exchange Commission (search) may sue the company for alleged violations of federal securities laws, based on allegedly misleading statements AIG made in recent press releases.

Office Depot Inc. (ODP) rose after it announced that chairman and chief executive Bruce Nelson resigned his post after reaching an agreement with the company's board of directors. Director Neil Austrian will serve as interim chairman and CEO until a permanent replacement is found. Shares were up 6 cents to $15.14 on the NYSE.

PeopleSoft Inc. (PSFT) said it expected increases in both revenue and net income for the third quarter. The company, which fired president and chief executive Craig Conway on Friday, is now considered to be on track to be acquired by Oracle Corp. (ORCL), which fought a bitter battle with the Conway-led software maker. PeopleSoft dropped 63 cents to $22.20 after gaining 15 percent on Friday, and Oracle slipped 2 cents to $11.987.

Charles Schwab & Co. Inc. (SCH) was down 15 cents at $9.07 after its brokerage subsidiary said it would reduce commissions for its online trading customers. The base online equity commission was to be slashed by a third, and the company said it would expand its $9.95 commission program for active online traders.

On the economic front, U.S. August factory orders fell for the first time in four months, the Commerce Department said Monday, with demand dropping sharply for commercial airplanes and parts. Overall, factory orders declined by 0.1 percent in August, following an increase of 1.7 percent in July. August's drop was the first since April, when orders declined by 1.1 percent.

Advancing issues outnumbered decliners by nearly 8 to 5 on the New York Stock Exchange, where volume came to 1.53 billion shares, compared with 1.58 billion on Friday.

The Russell 2000 index of smaller companies was up 4.06, or 0.7 percent, at 589.09.

Overseas, Japan's Nikkei stock average soared 2.7 percent. In Europe, Britain's FTSE 100 closed up 0.5 percent, while Germany's DAX index and France's CAC-40 both gained 1 percent.

Reuters and The Associated Press contributed to this report.