NEW YORK (CNN/Money) - Blue-chips ended with solid gains Thursday as investors turned bullish on positive economic data and a flurry of good corporate news.

Meanwhile, techs clung to gains thanks to upbeat chip-sector forecasts, and Dell reported results that disappointed Wall Street after the closing bell.

The Dow Jones industrial average (up 85.50 to 10,749.61, Charts) ended the session up 0.8 percent and the broader Standard & Poor's 500 (up 5.02 to 1,197.01, Charts) gained 0.4 percent.

The Nasdaq composite (up 0.55 to 2,053.10, Charts) was little changed at the end of the day, while the Philadelphia Semiconductor Index rose 0.6 percent on a chip-stock rally fueled by several brokerage upgrades for the sector.

American International Group (Research), up 4.7 percent, and Office Depot (Research), up 4.2 percent, paved the way for blue-chip gains thanks to healthy earnings reports. The insurer posted a 12 percent jump in net profit, while the retailer said it earned 30 cents a share, about 9 cents better than Wall Street forecasts.

"The rally will extend and challenge December highs," said Jeffrey Saut, chief market strategist at Raymond James. "But it's not a bull market. We're just bouncing back from January lows back to the top end of the trading range."

Seventeen of the Dow 30 ended the day in positive territory.

AIG, along with insurers St. Paul Travelers (Research), Allstate (Research) and Chubb (Research) rose after the Senate passed a class-action reform bill that would move many such suits from state to federal courts.

Upbeat economic releases also gave stocks a lift, with the Commerce Department saying the U.S. trade deficit in December fell to $56.4 billion from a monthly record in November, though the full-year the gap soared 24 percent to a record $618 billion.

Separately, the Labor Department said the number of workers filing initial jobless claims fell to 303,000, the lowest in over four years. Economists had forecast a rise in claims to 325,000.

"The narrowing of the trade gap and claims coming in at four-year lows has a lot to do with today's market action," Saut said.

Hewlett-Packard (down $0.05 to $21.48, Research) ended the day down 0.4 percent and continued to slide after the bell as investors took profits following the company's 7 percent jump Wednesday on news that CEO Carly Fiorina had been ousted by the computer maker's board.

Prudential Equity downgraded HP to "underweight" Thursday, citing increased uncertainty in the wake of Fiorina's departure.

Market breadth was mixed. On the New York Stock Exchange, winners topped losers 6-to-5 as 1.5 billion shares changed hands. On the Nasdaq, decliners beat out advancers 8-to-7 on volume of 2.1 billion shares.

Dell Inc. (Research), the world's largest personal computer maker, reported better-than-expected earnings for the fourth quarter, with profits excluding a charge coming in at 37 cents a share, a penny higher than consensus estimates.

But sales jumped came in a shade below forecasts of $13.54 billion, and the company issued mixed first-quarter guidance, sending shares down more than 3 percent after the bell.

Tech shares struggled Thursday, managing to regain ground lost earlier in the session after a semiconductor rally helped offset a broader tech slide.

Banc of America raised its view on the programmable logic device and analog semiconductor sector to "neutral" from "underweight," saying inventories have come down.

The firm also upgraded eight chip or chip equipment makers, including Altera (up $0.35 to $19.87, Research), which jumped 1.8 percent, and National Semiconductor (Research), which also ended the session up 1.8 percent.

Meanwhile, Think Equity Partners upgraded 10 chip stocks including Intel (Research), which advanced 0.9 percent, and Texas Instruments (Research), which added more than 1 percent, citing lower inventories in Asia and a reduced risk outlook in 2005.

Grocery chain Winn-Dixie (Research) skidded nearly 36 percent -- placing it among the NYSE's leading decliners -- after posting a wider second-quarter loss.

Swedish cell phone maker Ericsson (down $2.56 to $28.83, Research) also fell, tumbling more than 8 percent on disappointing profit margins. Competitors Nokia (up $0.14 to $15.81, Research) and Motorola (up $0.18 to $15.88, Research) both advanced around 1 percent.

A Wall Street Journal article saying that Verizon made an informal offer to acquire MCI garnered investor attention. The paper said the offer is near the $6.3 billion offer made by rival Qwest (Research), which slid 2.8 percent.

Verizon (Research) edged lower at the end of the session and MCI (Research) fell nearly 2 percent.

Sprint Corp. (Research) fell 1.8 percent after the company said it continues to project net operating revenue growth for 2005 in a "low single-digit" range.

Foodmaker Sara Lee (Research) saw shares jump 4.1 percent on news it would sell or spin-off its non-core units and that President Brenda Barnes has been promoted to chief executive.

Meanwhile, some major energy stocks also got a boost from a jump in oil prices on back of a report showing a decline in U.S. inventories, including ExxonMobil Corp. (Research), which gained 1.4 percent and moved higher after the bell, and ChevronTexaco Corp. (Research), which gained 2 percent.

The March light crude contract gained $1.64 to $47.10 a barrel on the New York Mercantile Exchange, after trading above $47 earlier in the session.

The dollar ended the day higher the yen and down against the euro.

Treasuries fell sharply after their recent rally, with the yield on the 10-year closing at 4.07 percent, up from 3.98 percent late Wednesday. Bond prices and yields move in opposite directions.

Tokyo's Nikkei closed at a seven-week high Thursday. Other major markets in Asia were closed for the lunar new year holiday.

Major European bourses ended flat after sluggish earnings from DaimlerChrysler (up $0.02 to $46.10, Research) and Ericsson (down $2.56 to $28.83, Research). (Click here for a closer look at world markets).