NEW YORK (CNN/Money) - U.S. stocks closed out a volatile day in positive territory Thursday, with a late-session rally in techs helping markets extend the previous session's SEC certification deadline rally despite mixed economic news.

The Dow Jones industrial average gained 74.83, or 0.86 percent, to 8,818.14. The Nasdaq composite added 10.71, or 0.80 percent, to 1,345.01. The Standard & Poor's 500 index rose 10.63, or 1.16 percent, to stand at 930.25.

"There was tremendous buying momentum at the close, especially in the last 20 minutes. The shorts jumped in, the institutions ... It was a technical buyback," John Pickett, a specialist at LaBranche & Co. told CNNfn's Street Sweep. "But it still was a very encouraging day as far as I am concerned. People are feeling more confident about this market now."

After the close of trade, Dell Computer (DELL: down $0.01 to $27.14, Research, Estimates) reported earnings per share of 19 cents in the second quarter, in line with estimates and up from the 16 cents earned in the year-earlier period. The company also said that it expects higher revenue in its third quarter. The report is likely to influence trade Friday.

Friday also brings economic reports on consumer prices, the government's main inflation gauge, housing starts and the preliminary reading on consumer sentiment from the University of Michigan.

Stocks had dipped at midday Thursday following a weak regional manufacturing report, but a second attempt at a tech rally pushed stocks higher in late-afternoon trade.

Among the stocks giving the market its fuel: data storage maker Brocade Communications (BRCD: up $0.91 to $15.96, Research, Estimates), which reaffirmed its forecast for improved profits in its current quarter and reported a fiscal third-quarter profit of 8 cents per share, in line with estimates and better than the 5 cents earned a year earlier.

Dow component and computer maker Hewlett-Packard (HPQ: up $0.37 to $15.00, Research, Estimates) rose after Lehman Bros. upgraded the company's shares to "equal-weight" from "under-weight," based on valuation and on the belief that U.S. enterprise demand is stabilizing. The firm trimmed its 2002 and 2003 profit estimates for the company, but raised its stock price target.

Business software maker BEA Systems (BEAS: up $0.36 to $6.12, Research, Estimates) rallied after the company said late Wednesday that it earned 6 cents per share in its second quarter, in line with estimates but down from the 10 cents per share earned a year earlier. BEA also said that, in the current quarter, it expects revenue and profit excluding items to be about the same or slightly higher than the second quarter.

Amid a broadly positive Dow, No. 1 retailer Wal-Mart Stores (WMT: up $2.09 to $54.71, Research, Estimates) was a standout. The company rallied after it said Wednesday that it would expense stock options and institute a new $5 billion share buyback program that would replace an existing one. News of a buyback by a company often will boost the stock as it's seen as a sign of corporate confidence.

"The overall bias of the market is still upward. It's not going to be a rocketship to the sky, but the worst is over in terms of the panic-driven selling of June and July," said Douglas Altabef, managing director at Matrix Asset Advisors.

Wednesday was the deadline for 697 CEOs to certify the accuracy of their financial statements with the Securities and Exchange Commission, and most did so. Dynegy (DYN: down $0.19 to $1.30, Research, Estimates) and a few other companies were unable to sign off on their books, but the vast majority did, reassuring investors who have been plagued by the corporate governance scandals that have hurt markets for months.

"Everyone was poo-pooing the relevance of the certification deadline yesterday [Wednesday], but it had a good effect. Almost everyone who needed to certify did it," said Michelle Clayman, chief investment officer at New Amsterdam Partners.

Shares of media conglomerate AOL Time Warner (AOL: up $0.81 to $11.86, Research, Estimates), the parent of CNN/Money, rallied after the company signed off on its financials even though it also said it may have exaggerated revenue at its AOL unit.

"The certification helps sentiment, and you're also just seeing companies step forward more and announcing to investors if they're being investigated or are having problems, rather than being outed," said Matrix's Altabef.

To see a list of which companies have signed off, click here.

"We're also still getting support from the low interest rates. While Treasury yields are not as low today as they've been, they are still historically at a substantial low, and that lends support to equities," New Amsterdam's Clayman said.

Treasury prices backed off from big gains in the prior two sessions, sending the 10-year note yield up to 4.18 percent from 4.11 percent late Wednesday.

But the news was not all rosy.

Goldman Sachs lowered 2003 and three-year estimates for the computer hardware group, saying it's not realistic to wait out the information technology spending slowdown. The firm also downgraded No. 1 Unix server maker Sun Microsystems (SUNW: down $0.33 to $4.11, Research, Estimates) to "market performer" from the firm's "recommended list."

Financial services provider J.P. Morgan Chase (JPM: down $0.35 to $24.79, Research, Estimates) is at risk to have its credit rating downgraded by ratings firm Standard & Poor's, due to the weak economy. Merrill Lynch (MER: up $1.05 to $36.32, Research, Estimates), Goldman Sachs (GS: up $1.05 to $79.55, Research, Estimates) and Morgan Stanley (MWD: up $0.21 to $44.22, Research, Estimates) face the same risk.

Midday brought the release of a surprisingly weak Philadelphia Fed index, a key measure of regional manufacturing activity. The August index fell to minus 3.1 after being plus 6.6 in July, creating fears that the manufacturing slowdown in July was not an aberration but a new trend.

In the day's other economic news, the number of Americans filing for first-time jobless claims rose by 6,000 to 388,000 last week, the government said. A separate report showed that industrial production rose 0.2 percent in July, the seventh straight month of gains, following a revised 0.7 percent gain in June. Capacity utilization was 76.1 percent, unchanged from June.

Light crude oil futures gained 87 cents to $28.38 a barrel, while gold rose. The dollar was a little higher versus the euro and mostly flat versus the yen.

Market breadth was positive. On the New York Stock Exchange, winners topped losers nearly 5-to-3 as 1.49 billion shares changed hands. On the Nasdaq, advancers edged decliners as 1.72 billion shares traded.