Oct. 10--The stock market ended one of its worst weeks in history Friday, with a stomach-wrenching roller coaster of a day that offered moments of exhilaration but left deepening concerns about a global economic emergency.

Tech stocks fared better than some other sectors. The tech-heavy Nasdaq Composite Index ended the day up 4.39 points, or slightly more than a quarter of a percent. Apple rose 9 percent, and eBay jumped almost 5 percent, while Hewlett-Packard, Microsoft and Intel fell.

But the S&P 500 ended the day down 1.2 percent, after falling 18 percent for the week, its worst one-week decline since 1933. And all eyes were on the Dow Jones industrial average -- which also fell 18 percent over the previous five days, for its worst week in history.

The Dow plunged almost 700 points Friday morning, then rose and fell several times before climbing almost 300 points into positive territory in late afternoon, as leaders from seven economic powers gathered in Washington to address the financial crisis. It dropped again at the end of the day and closed at 8,451.49 -- down 128 points or 1.5 percent for the day.

"With this kind of volatility, there's only one explanation: There's an unprecedented amount of fear in the marketplace," said Sung Won Sohn, former Wells Fargo chief economist and now professor at California State University-Channel Islands. "Logic does not prevail anymore."

The Dow's decline for the week was worse than

its previous record 17 percent drop in one week in 1933. The previous five days also saw the Nasdaq drop 15 percent. Sohn called it "the darkest economic moment" of his 30-year career.

President Bush sought to reassure Americans earlier in the day, after stock markets fell in Europe and Asia, as the global credit crunch sparked calls for a coordinated response.

"We can solve this crisis and we will," Bush said in brief remarks at the White House.

But experts warned that investors are increasingly skeptical about the ability of governments to counter the deepening crisis, as attempts to bail out individual companies, and even last week's passage of a $700 billion package for the U.S. financial industry, have failed to stem the tide.

Each day's news of financial problems around the world has "created a snowballing effect" that drives more investors to take money out of the stock market, Sohn said.

Analysts offered conflicting explanations for Friday's late-day surge: Some said investors may have decided the market was reaching bottom; others said a wave of purchases was triggered by automated "buy" orders that kicked in when prices fell below pre-set levels.

Along with the spreading credit freeze, investors saw increasing signs this week that the U.S. downturn had become a worldwide phenomenon.

Earlier this week, Citigroup analyst Richard Gardner lowered his earnings estimates for major hardware companies including Hewlett-Packard, IBM, Dell and Sun Microsystems, while projecting that growth in global PC sales would slow to 13 percent this year and drop to 5 percent in 2009.

Citigroup also lowered its estimates for Oracle and other business software companies, saying it appears that corporations will cut back on purchasing new licenses over the next year.

But Oracle Chief Executive Larry Ellison promised investors Friday that the Redwood City company will remain profitable "even if times are tough." Oracle's stock rose nearly 3 percent Friday, closing at $16.68, though it's down from a 52-week high of $23.62 in early August.

Stanford economist Michael Boskin, who sits on Oracle's board, did not dispute Ellison's remarks at the company's annual shareholders meeting. Still, he said, the nation is in a recession and "in the midst of financial panic." Even with government intervention, he added, "I think the next two or three quarters are going to be very rough."

Contact Brandon Bailey at bbailey@mercurynews.com or (408) 920-5022.

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