The S&P 500 and the Dow were set for their worst day since October as the lack of details on economic policy in Donald Trump's speech took the wind out of a record-setting post-election rally.
The losses were broad-based. All of the 11 major S&P 500 sectors were lower, with the technology, financial and industrial sectors all down 1 percent or more.
In his first news conference since election, Trump on Wednesday gave no details on tax cuts or infrastructure spending. He instead lashed out at U.S. spy agencies and media houses over what he called a 'phony' Russia dossier.
Trump also blasted pharmaceutical companies over high drug prices, causing health stocks to snap a six-day winning streak and a wobble on Wall Street.
"Some wind has been taken out of the reflation trade, at least for the short term," said Jeff Zipper, managing director at the Private Client Reserve, U.S. Bank in Florida.
"There is a high probability of more volatility if his agenda does not go through or may take longer than he expects."
At 11:06 a.m. ET the Dow Jones Industrial Average was down 177.03 points, or 0.89 percent, at 19,777.25 and the S&P 500 was down 20.34 points, or 0.89 percent, at 2,254.98.
The Nasdaq Composite was down 65.74 points, or 1.18 percent, at 5,497.91, set for its biggest one-day drop since Dec. 1.
The CBOE Volatility Index or Wall Street's "fear gauge," ticked up 11.6 percent, the most since the U.S. election.
The dollar was at a one-month low, while gold rose to its highest since late November.
The financial index tumbled 1.5 percent, set for its worst day since Sept. 29. The decline comes one day before a trio of big banks report results, kicking off the fourth-quarter earnings season.
Merck, one of the few health stocks that avoided Wednesday's carnage, gained 2.1 percent after multiple broker upgrades.
The drugmaker's fellow Dow component Disney Co was off 1.7 percent at $107.62 after Pivotal cut its rating on the stock to 'sell'.
Microsoft fell 1.8 percent and Apple dropped 1.2, making them the biggest drags on the S&P and the Nasdaq.
Declining issues outnumbered advancers on the NYSE by 2,080 to 728. On the Nasdaq, 2,157 issues fell and 527 advanced.
The S&P 500 index showed six new 52-week highs and three new lows, while the Nasdaq recorded 28 new highs and 16 new lows. (Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Savio D'Souza)