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* Tariff increase on $200 bln of Chinese goods takes effect

* Symantec plunges on profit warning, CEO departure

* Uber opens 6.7% below IPO price

* Indexes down: Dow 0.55%, S&P 0.61%, Nasdaq 0.93% (Updates prices to open)

By Amy Caren Daniel

May 10 (Reuters) – U.S. stocks were off session lows on Friday, but the benchmark S&P 500 remained on track for its worst weekly loss since December, as investors fretted over a potential long-drawn U.S.-China trade war.

Treasury Secretary Steven Mnuchin called the two-day talks that ended in Washington “constructive”, lifting sentiment that was earlier weighed down by President Donald Trump saying he was in