As jitters about the election subsided, traders confronted an ugly reality: The so-called fiscal cliff, which will impose automatic tax increases and deep cuts to government spending at the end of the year unless the president and Congress reach a deal.
That's no easy task for a deadlocked government whose overall composition has barely changed — a Democratic president and Senate and a Republican House.
If Congress and the White House don't reach a deal, the spending cuts and tax increases could total $800 billion next year. Some economists say that could push the economy back into recession.
"Obama's re-election does not change the bigger economic or fiscal picture," Paul Ashworth of Capital Economics, an economic research company, said in a note to clients.
Fitch Ratings offered a warning Wednesday about the perils facing the U.S. If Obama does not quickly forge agreement with Congress to avert the fiscal cliff, the credit rating agency said, it may strip the U.S. of its sterling AAA credit rating.
The government's failure to come up with a plan to reduce the deficit led Standard & Poor's to cut its rating of long-term U.S. Treasury securities last year from a sterling AAA to AA+. It was the first-ever downgrade of U.S. government debt.
Tobias Levkovich, a financial analyst at Citi Research, told clients Wednesday that a compromise on taxes and spending was likely in mid- to late January, but that stocks will probably fall in the meantime.
A deal early next year is much more likely "once the political class begins to negotiate realistically and as the consequences ... are too costly for either party to ignore," he wrote.
European markets closed sharply lower, with benchmark indexes in France and Germany losing 2 percent. Italy lost 2.5 percent; Spain lost 2.3 percent.
As traders streamed into lower-risk investments, the yield on the 10-year Treasury note plunged to 1.64 percent from 1.75 percent late Tuesday. A bond's yield declines as demand for it increases.
Most industries reacted to the election much as analysts had expected.
Big, publicly traded hospital companies soared because of expectations that they will gain business under the health care law, known as ObamaCare. HCA Holdings leapt 9.4 percent, Tenet Healthcare 9.6 percent, Community Health Systems 6 percent and Universal Health Services 4.3 percent.
Not all hospital companies are expected to benefit. Many serve patients who will be covered by Medicaid plans that generally do not cover the full cost of care provided by hospitals.
Health insurance stocks sank, defying many analysts' expectations. ObamaCare will expand coverage of the uninsured in 2014, giving insurers millions of new customers. But the overhaul also imposes fees and restrictions on the companies, potentially threatening their profitability. Humana slid 7.9 percent, UnitedHealth Group 3.8 percent, Aetna 4.2 percent and Wellpoint 5.5 percent.
With Obama seeking to restrain the growth of military spending, defense companies could struggle to win government contracts. Their stocks fell sharply: Lockheed Martin lost 3.9 percent, Northrop Grumman 4.6 percent and General Dynamics 3.9 percent.
Among the 10 industry groups in the S&P 500 index, financial stocks and energy companies fell the most.
Banks figure to face tougher regulation in a second Obama term than they would have under Romney. JPMorgan Chase fell 5.6 percent, Citigroup 6.3 percent, Bank of America 7.1 percent, Goldman Sachs 6.6 percent and Morgan Stanley 8.6 percent.
The biggest losers were coal companies, which had hoped that a Romney administration would loosen mine safety and pollution rules that make it more costly for them to operate. Peabody Energy dived 9.6 percent, Consol Energy 6.1 percent, Alpha Natural Resources 12.2 percent and Arch Coal 12.5 percent.
Oil companies fell less steeply.
Trading also reflected the outcome of ballot measures decided in Tuesday's election. After two states approved the recreational use of marijuana for the first time, Medical Marijuana Inc., a company too small to be listed on major exchanges, surged 22 percent.
Other notable moves included Apple, the world's most valuable company. It fell 3.8 percent to $558.00 and has dropped 20 percent from its all-time high of $705.07, reached Sept. 21.
AP Business Writers Christina Rexrode and Steve Rothwell in New York, Tom Murphy in Indianapolis, Linda Johnson in Trenton, N.J. and Marcy Gordon in Washington contributed to this report.
Daniel Wagner can be reached at www.twitter.com/wagnerreports.