Sun Microsystems Inc. jumped, helping lift computer-related stocks, after Merrill Lynch & Co. advised investors to buy technology shares.

The Nasdaq Composite Index rose 48.04, or 2.6 percent, to 1929.67. The Standard & Poor's 500 Index climbed 6.77, or 0.6 percent, to 1164.31. The Dow Jones Industrial Average gained 47.12, or 0.5 percent, to 10,572.49, completing its first four-week winning streak since May.

For the week, the Dow gained 2 percent, extending its year-to- date advance to 5.5 percent. The S&P 500 rallied 2.9 percent this week, erasing the benchmark's loss for the year.

The Nasdaq rose 7 percent, paring its year-to-date decline to 1.1 percent. It was down 12 percent as recently as two weeks ago.

"It's tough to argue against" an economic rebound, said Joe Balestrino, whose $290 million Federated Stock and Bond Fund this week shifted money to stocks from bonds for the first time in two years. "We are bottoming right now from a corporate earnings perspective and have already bottomed from an economic perspective."

About 1.4 billion shares traded on the New York Stock Exchange, 3.2 percent more than the three-month daily average. Advancing and declining stocks were about even on the Big Board, while almost two rose for every one that fell on the Nasdaq Stock Market.

Sun Microsystems, whose server computers run corporate networks and Web sites, gained $1.17 to $10. The company reiterated forecasts that fiscal third-quarter revenue will rise "slightly" from last quarter's $3.11 billion.

Cisco Systems Inc., the largest maker of equipment to direct Internet traffic, gained 80 cents to $17.80. Intel, the biggest chipmaker, rose $1.19 to $34.17.

Microsoft led software companies higher. The biggest software maker rose $1.23 to $63.95, Oracle Corp. advanced 20 cents to $14.20 and Veritas Software Corp. rose $1.26 to $44.41.

Merrill strategist Steven Milunovich reversed a call he made two months ago that technology stocks were too expensive and should be avoided. Today, he said "increasing signs of a bottom" in technology businesses and reports showing improvement in the overall economy have changed investor sentiment.

The Russell 2000 index advanced 4.93 to 499.85.