NEW YORK

A case of postelection nerves sent Wall Street plunging Wednesday as investors absorbed a stream of bad economic news abd wondered how a Barack Obama presidency will help the country weather a possibly severe recession. Volatility returned to the market, with the Dow Jones industrials falling nearly 500 points and all the major indexes tumbling more than 5 percent.

The market was expected to give back some gains after a six-day runup that lifted the Standard & Poor's 500 index more than 18 percent. But investors lost their recent confidence about the economy and began dumping stocks again; light volume helped exaggerate the price swings.

"The market has really gotten ahead of itself, and falsely priced in that this recession wasn't going to be as prolonged as thought," said Ryan Larson, head of equity trading at Voyageur Asset Management, a subsidiary of RBC Dain Rauscher.

"We're in a really bad recession, period," he said. "Wall Street can spin it anyway they want to, but this is likely going to be more prolonged than people anticipated. People are locking in profits and realizing we're not out of the woods."

Beyond broad economic concerns, worries about the financial sector intensified after Goldman Sachs Group Inc. began to notify about 3,200 employees globally that they have been lost their jobs as part of a broader plan to slash 10 percent of the investment bank's work force, a person familiar with the situation said. The cuts were first reported last month. Goldman fell 8 percent, while other financial names also fell; Citigroup Inc. dropped 14 percent.

Commodities stocks also fell after steelmaker ArcelorMittal said it would slash production because of weakening demand. Its stock plunged 21.5 percent.

Although the market expected Obama to win the election, as the session wore on investors were clearly worrying about the weakness of the economy and pondered what the Obama administration might do to help it. Analysts said the market is already anxious about who Obama selects as the next Treasury Secretary, as well as who he picks for other Cabinet positions.

"The celebration is over. Today we saw a bit of reality," said Al Goldman, chief market strategist at Wachovia Securities in St. Louis. "President-elect Obama is coming into a situation with limited experience, having to handle an economy in serious trouble, a couple of wars and terrorism. It's an extremely tough job."

Analysts said investors were also uneasy in advance of the Labor Department's October employment report, to be issued Friday. Economists, on average, expect a 200,000 drop in payrolls, according to Thomson/IFR.

Late-day selling by hedge funds helped deepen the market's losses during the last hour. More selling by the funds is expected to weigh on the market ahead of a Nov. 15 cutoff for shareholders to notify fund managers of their intent to cash out investments before year-end.

The Dow fell 486.01, or 5.05 percent, to 9,139.27.

The S&P 500 index fell 52.98, or 5.27 percent, to 952.77. Through the six sessions that ended Tuesday, the index, the one most closely watched by market professionals, rose 18.3 percent.

The Nasdaq composite index fell 98.48, or 5.53 percent, to 1,681.64, while the Russell 2000 index of smaller companies fell 31.33, or 5.74 percent, to 514.64.

Declining issues outnumbered advancers by about 4 to 1 on the New York Stock Exchange, where volume came to a light 1.31 billion shares.

Wednesday's trading, which followed a 300-point jump in the Dow on Tuesday, showed that the market is living up to expectations of continued volatility as it tries to recover from the devastating losses of the last two months.

Bill Stone, chief investment strategist at PNC Wealth Management, said the uncertainty over the direction the government's financial bailout plan will take under the next administration likely weighed on financial stocks Wednesday.

Analysts agree that Obama's most immediate priority will be dealing with the nation's financial crisis and deciding how to further implement the $700 billion rescue package passed by Congress last month.

Goldman said trading could remain turbulent as investors begin assessing the shape and direction of Obama's forthcoming economic policies.

"The market has to go through a period of figuring out if they are going to gain confidence in Obama and the Congress or lose it," he said, adding that investors will be paying close attention to who will be appointed to top economic posts.

Obama's victory means that industries such as oil and gas producers, utilities and pharmaceuticals may face greater regulation and even taxes, while labor unions and automakers are expected to benefit.

In addition, banks, insurance companies, hedge funds and the rest of the financial sector will almost certainly face attempts at a regulatory overhaul by the Democratic Congress next year.

Bank of America Corp. dropped $2.78, or 11.3 percent, to $21.75. Citigroup fell $2.05, or 14 percent, to $12.63. Morgan Stanley, meanwhile, tumbled $1.84, or 9.7 percent, to $17.06. Goldman Sachs fell $7.57, or 8 percent, to $87.43.

In addition to monitoring the direction the next administration will take, investors continue to heed the state of the credit markets. The paralysis in the credit markets that began after the bankruptcy of Lehman Brothers Holdings Inc. in mid-September has been alleviated somewhat by a series of government interventions, but they still show some signs of strain.

Banks continued to ratchet down the rates they charge one another for borrowing on Wednesday, but the key interbank lending rate - the London Interbank Offered Rate, or Libor - remains well above the Federal Reserve's target interest rate of 1 percent. Libor for three-month dollar loans fell to 2.51 percent from 2.71 percent Tuesday.

And the bid for Treasury bills remains high. The three-month bill, considered one of the safest assets around, fell to 0.40 percent from 0.48 percent late Tuesday. A low yield indicates high demand.

The yield on the benchmark 10-year Treasury note fell slightly to 3.71 percent from 3.73 percent late Tuesday.

The dollar was mixed against other major currencies, while gold prices fell.

Other sectors that are being closely watched in light of the election results are pharmaceuticals and alternative energy, analysts said.

Merck & Co. fell $2.41, or 7.7 percent, to $28.72. Pfizer Inc., meanwhile, dipped $1.09, or 6 percent, to $17. SunTech Power Holdings Co. was among the alternative energy stocks that declined, falling $6.82, or 21.5 percent, to $24.88.

Light, sweet crude dropped $5.23 to $65.30 a barrel on the New York Mercantile Exchange.

In Asian trading, Japan's Nikkei index rose 4.46 percent, and Hong Kong's Hang Seng Index rose 3.17 percent. Britain's FTSE 100 fell 2.34 percent, Germany's DAX index fell 2.11 percent, and France's CAC-40 fell 1.98 percent.