NEW YORK (REUTERS) - Wall Street opened lower on Thursday (Nov 9) and the Dow lost 100 points as tech stocks pulled back and skepticism over a Republican tax overhaul plan weighed.

A US Senate tax-cut bill, differing from one already in the House of Representatives, was expected to be unveiled on Thursday, complicating a tax overhaul push.

The S&P 500 has risen about 21 per cent since the election of President Donald Trump a year ago, partly on the back of his promises to cut taxes and other business-friendly measures.

However, Republicans are yet to score a major legislative win since Trump took office in January, even though the party controls both chambers of Congress as well as the White House.

Investors were also concerned about the potential fallout from Democrat wins in regional US elections this week - a signal for next year's mid-term Congressional elections for Trump.

"With concerns rising over possible delays in the US tax reforms, equity bears could make an unwelcome appearance, consequently exposing global stocks to downside risks," said Lukman Otunuga, research analyst at FXTM.

"Investors should also keep in mind that geopolitical tensions and political risk in the background, have the ability spark risk aversion."

In early trading, the Dow Jones Industrial Average was down 114.97 points, or 0.49 per cent, at 23,448.39, the S&P 500 was down 13.57 points, or 0.52 per cent, at 2,580.81. The Nasdaq Composite was down 60.38 points, or 0.89 per cent, at 6,728.74.

Ten of the 11 major S&P sectors were lower, with the technology and Materials indexes leading the decliners.

Technology has been the best performing S&P sector so far this year with a 37 per cent rise, despite concerns of stretched valuations.

Ebay's 4.1 per cent fall weighed the most on the Nasdaq. With third-quarter earning season winding down, earnings for the quarter are expected to have climbed 8 per cent, compared with expectations of a 5.9 per cent rise at the start of October, according to Thomson Reuters I/B/E/S.

Shares of Roku soared 37.3 per cent after the television streaming device maker's quarterly results and guidance beat expectations.

Kohl's was down 3.8 per cent after the department store operator's quarterly profit missed estimates.

Coty rose 17.8 per cent after the beauty products maker's quarterly profit beat Wall Street estimates.

Declining issues outnumbered advancers on the NYSE by 1,887 to 729.

On the Nasdaq, 1,850 issues fell and 589 advanced.