US stock markets tumbled Wednesday after President Barack Obama's re-election victory set up a tough battle with Republicans over the looming "fiscal cliff".
In the first half hour of trade, the Dow Jones Industrial Average dropped 197.98 points (1.49 percent) to 13,047.70.
The broad-based S&P 500 fell 20.51 (1.44 percent) to 1,407.88, while the Nasdaq Composite shed 39.37 (1.31 percent) at 2,972.56.
Obama won a resounding victory over Republican challenger Mitt Romney in a closely fought race late Tuesday.
But voters left Congress divided, with Democrats maintaining the Senate and Republicans holding the House of Representatives.
"Focus now shifts to the upcoming fiscal cliff of tax increases and spending cuts that go into effect in 2013 unless a budget compromise is met by Congress," said Wells Fargo Advisors analysts.
"By returning a divided government to Washington, the electorate has given neither party a clear mandate to address the lackluster recovery, the fiscal cliff, and the looming debt crisis," said Brian Kessler at Moody's Analytics.
The broad market sell-off was led by telecommunications and financial stocks. On the blue-chip Dow, Bank of America dived 3.8 percent, JPMorgan Chase shed 3.2 percent and AT&T lost 2.9 percent.
Alcoa dropped 2.1 percent, Caterpillar fell 1.5 percent and United Technologies was down 1.9 percent.
On the Nasdaq, heavyweight Apple dropped 1.7 percent.
Market sentiment was also pressured by flared-up concerns about the eurozone economic crisis, after European Central Bank chief Mario Draghi warned that the bloc's woes were beginning to hurt Germany, Charles Schwab & Co. analysts said.
Bond prices jumped as investors fled equities. The 10-year US Treasury yield fell to 1.63 percent from 1.74 percent late Tuesday, and the 30-year tumbled to 2.82 percent from 2.92 percent. Prices and yields move inversely.