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* China to halve extra tariffs on some U.S. imports
* U.S. weekly jobless claims hit nine-month low
* Becton Dickinson tumbles after forecast cut
* Twitter advances as quarterly revenue tops $1 bln
* Indexes up: Dow 0.3%, S&P 0.33%, Nasdaq 0.67% (Updates to close of U.S. market)
By Lewis Krauskopf
Feb 6 (Reuters) - U.S. stocks gained for a fourth straight session on Thursday and Wall Street's main indexes hit record highs as concerns eased over the economic fallout from the coronavirus outbreak in China.
China said it would halve additional tariffs levied against some U.S. goods, seen by analysts as a move to boost confidence after the fast-spreading coronavirus disrupted businesses and sparked broad market volatility.
“The one primary thing that everyone has been listening to and watching and seeing how it moves the market has been the coronavirus," said Jonathan Corpina, senior managing partner for Meridian Equity Partners in New York. "The headlines have been somewhat neutral lately, and that has been acceptable for the markets.”
Adding to the optimism for stocks were data showing that the number of Americans filing for unemployment benefits dropped to a nine-month low last week, with investors casting an eye toward Friday's monthly U.S. employment report.
The Dow Jones Industrial Average rose 88.92 points, or 0.3%, to 29,379.77, the S&P 500 gained 11.09 points, or 0.33%, to 3,345.78 and the Nasdaq Composite added 63.47 points, or 0.67%, to 9,572.15.
Among S&P 500 sectors, communication services and technology led the way, while energy fell the most.
Even with optimism about containing the broad economic damage from the coronavirus, the impact of the health emergency in China continued to show up in corporate reports. Chipmaker Qualcomm Inc flagged a potential threat to the mobile phone industry from the outbreak. Its shares fell 0.3%.
Investors were also digesting the acquittal on Wednesday of U.S. President Donald Trump on impeachment charges.
"The outcome was fairly well telegraphed and I think widely believed, but it ends the chapter for now and I think that is a modest positive for investor sentiment,” said James Ragan, director of wealth management research at D.A. Davidson in Seattle.
With the fourth-quarter corporate reporting season more than halfway completed, S&P 500 companies are expected to have increased earnings by 2.1% for the period, according to IBES data from Refinitiv.
In earnings news, Becton Dickinson and Co shares slid 11.8%, contributing the biggest drag on the S&P 500, after the medical technology company cut its 2020 forecast.
Kellogg shares slumped 8.5% after the breakfast cereal maker forecast full-year earnings that widely missed market expectations.
Twitter shares soared 15.0% after the social media company reported $1 billion in quarterly revenue for the first time.
Philip Morris International shares rose 2.7% after the tobacco company released results.
Advancing issues outnumbered declining ones on the NYSE by a 1.07-to-1 ratio; on Nasdaq, a 1.11-to-1 ratio favored decliners.
The S&P 500 posted 62 new 52-week highs and no new lows; the Nasdaq Composite recorded 122 new highs and 41 new lows.
About 7.3 billion shares changed hands in U.S. exchanges, below the 7.7 billion daily average over the last 20 sessions. (Reporting by Lewis Krauskopf Additional reporting by Medha Singh in Bengaluru Editing by Leslie Adler and Alistair Bell)