Wall Street ends lower on Trump uncertainty

U.S. stock indices closed lower after a volatile session, with S&P 500 closing modestly down after paring most of its losses, while Dow Jones marked its eighth daily decline in a row as markets fret over Trump's failure to pass his healthcare bill through Congress. 

The U.S. administration pulled the bill before vote even began due to weak support, which raised doubts in the markets about Trump's ability to deliver on his other promises to cut corporate taxes and expand spending. 

On the other hand, crude prices fell today amid concerns about market oversupply despite the earlier meeting between OPEC's members and other producers in the weekend, which resulted in promises to extend output cuts to the second half of the year. 

As for the dollar, it kept trading near a five-month low, but that failed to buoy shares of American exporters due to wavering and dampening risk appetite. 

Standard and Poor's 500 shed 0.22%, or 45.75 points to 20,550.98, while Dow Jones dipped 0.10%, or 2.39 points to 2,34.59. 

Tech-heavy NASDAQ was the sole winner, advancing 0.20%, or 11.64 points to 5,840.38.