* Yellen to speak at award presentation at 2:30 p.m. ET
* Valeant surges on better-than-expected profit
* Priceline, TripAdvisor fall on weak forecasts
* Indexes down: Dow 0.06 pct, S&P 0.02 pct, Nasdaq 0.28 pct (Adds details, changes comment, updates prices)
Nov 7 (Reuters) - Wall Street lost steam in late afternoon on Tuesday after scaling to record levels with the S&P and the Dow trading flat and the Nasdaq slipping on weak forecast from travel services company, Priceline.
Shares of Priceline fell 11 percent and that of travel-review website operator TripAdvisor hit a five-year low after the companies gave soft fourth-quarter profit forecasts.
Investors are also waiting for more clarity on President Donald Trump's tax-cut plan as the earnings season winds down.
Republicans plan to bring their tax overhaul bill for a vote next week, U.S. House Ways and Means Committee Chairman Kevin Brady said on Tuesday, adding that he expects the plan to pass.
House Republicans last week unveiled a first draft that proposed a range of cuts aimed at helping businesses, including slashing the corporate rate to 20 percent from 35 percent.
"The market is waiting for the next catalyst, which is the tax bill," said Adam Sarhan, chief executive of 50 Park Investments.
"It looks like, unless some major unforeseen event occurs, tax cuts will get passed in some shape or form. Whether (corporate tax cuts) it's 20 percent or 25 percent, a big tax cut is coming."
The S&P has risen about 15 percent in 2017 on the back on strong earnings, an improving economy and Trump's promise to cut taxes.
With more than 400 of S&P 500 companies having reported, earnings for the third quarter are expected to have climbed 8 percent, compared with expectations of a 5.9 percent rise at the start of October, according to Thomson Reuters I/B/E/S.
At 10:59 a.m. ET (1459 GMT), the Dow Jones Industrial Average was down 15.3 points, or 0.06 percent, at 23,533.12, the S&P 500 was down 0.55 points, or 0.02 percent, at 2,590.58.
The Nasdaq Composite was down 18.77 points, or 0.28 percent, at 6,767.67.
Seven of the 11 major S&P sectors were lower, with the financial index's 0.42 percent loss leading the decliners.
Investors will also lend an ear to a speech from outgoing Federal Reserve Chair Janet Yellen at a presentation of the Paul H. Douglas Award for Ethics in Government in Washington at 2:30 p.m. ET.
Her speech will come less than a week after President Donald Trump chose Fed governor Jerome Powell to replace Yellen at the end of her term in 2018.
Weight Watchers jumped 16.3 percent after the weight management company raised its profit forecast.
Valeant Pharma surged 14.8 percent after the company's profit beat Wall Street estimates.
Emerson Electric fell 2.5 percent as the factory automation equipment maker's forecast disappointed investors.
Declining issues outnumbered advancers on the NYSE by 1,638 to 1,090. On the Nasdaq, 1,972 issues fell and 803 advanced. (Reporting by Tanya Agrawal; Editing by Arun Koyyur)