US stocks were lower in early afternoon trading on Thursday as a steep fall in crude oil prices weighed on energy shares and with healthcare stocks in focus ahead of a cliffhanger vote on repealing Obamacare.
Lawmakers will vote later in the afternoon on a Republican healthcare bill to repeal and replace major portions of former President Barack Obama's signature healthcare act.
If the bill passes it will hand a major legislative victory to President Donald Trump, but will face steep hurdles in the Senate.
The S&P healthcare index was up 0.5 per cent, the second-biggest increase among the 11 major S&P 500 sectors.
The losers were led by the energy sector, which fell 2.24 per cent to its lowest level since August as crude oil prices slumped more than 4 per cent on fears of an oversupply.
Exxon and Chevron were among the biggest drags on the three major indexes.
Facebook also weighed on both the S&P 500 and Nasdaq as its shares fell 1 per cent after the company's outlook on advertising growth and expenses spooked investors.
Apple was down 0.5 per cent, and was the biggest drag on the Nasdaq.
At 12:52 pm ET (16:52 GMT) the Dow Jones Industrial Average was down 49.08 points, or 0.23 per cent, at 20,908.82.
The S&P 500 was down 2.16 points, or 0.09 per cent, at 2,385.97 and the Nasdaq Composite was down 5.10 points, or 0.08 per cent, at 6,067.45.
The US stock market had opened higher after the Federal Reserve indicated it could raise interest rates in June and downplayed recent weak economic data.
"I think the Fed's diagnosis of what happened in the first quarter was basically correct," said David Donabedian, chief investment officer of CIBC Atlantic Trust Private Wealth Management in Washington.
"The economic data waxes and wanes and there's clearly a seasonal adjustment in the first quarter from which we see a bounce back."
Futures traders are now pricing in a 72 per cent chance of June rate hike, up from 63 per cent before the Fed's statement on Wednesday, according to the CME Group's FedWatch Tool.
Earnings of S&P 500 companies have generally come in above expectations, pushing the benchmark index to within 1 percent of its all-time high. The estimated profit growth of 14.2 per cent is the strongest growth since 2011, according to Thomson Reuters I/B/E/S.
Tesla was down 4.7 per cent to $296.46 after the electric-car maker posted a bigger-than-expected loss.
Viacom fell 5.4 per cent to $37.12 on a softening advertisement market and news that Charter Communications has re-tiered five of Viacom's flagship networks.
Regeneron rose 5.7 per cent to $430.44 after the biotech company's revenue edged past analysts' estimates.
Declining issues outnumbered advancers on the NYSE by 2,062 to 825. On the Nasdaq, 1,692 issues fell and 1,068 advanced.
The S&P 500 index showed 38 new 52-week highs and 12 new lows, while the Nasdaq recorded 87 new highs and 60 new lows.