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* U.S. tariffs on $200 bln of Chinese goods expected in Sept
* U.S., Canada upbeat on trade talks with deadline on Friday
* Material sector drops as metal prices hit by trade woes
* Dollar Tree, Dollar General down on bleak forecasts
* Indexes down: Dow 0.22 pct, S&P 0.15 pct, Nasdaq 0.15 pct (Updates to open)
By Shreyashi Sanyal
Aug 30 (Reuters) - U.S. stocks fell on Thursday, after four days of gains, weighed down by weak results from retailers and on rising concerns over the U.S.-China trade war that has weighed on markets for most of the year.
Washington has proposed slapping tariffs on a further $200 billion worth of Chinese goods, which will come into effect next month after a public comment period ends on Wednesday, Sept. 5.
Metal prices fell as the Sino-U.S. trade tensions upstaged optimism that the United States and Canada could clinch a new North American Free Trade Agreement (NAFTA).
The S&P materials sector sank 0.94 percent, the most among the 11 major S&P sectors. The trade-sensitive industrials index fell 0.25 percent, led by Caterpillar's 1.1 percent decline.
The consumer discretionary index slid 0.35 percent on weak earnings from retailer Dollar Tree and a drop in Calvin Klein owner PVH Corp.
"I think this is an environment in which, if not for trade news, then we would be trading higher and we have seen that with the bumps in the Mexico trade talks," said Art Hogan, chief market strategist at B. Riley FBR in New York.
"We've had a pretty significant run and I think that we don't have any more good news to keep that momentum going which is why we're giving up gains, but very modestly."
At 10:06 a.m. ET the Dow Jones Industrial Average was down 58.65 points, or 0.22 percent, at 26,065.92, the S&P 500 was down 4.24 points, or 0.15 percent, at 2,909.80 and the Nasdaq Composite was down 12.40 points, or 0.15 percent, at 8,097.29.
Of the 11 S&P sectors, the biggest gainer was defensive utilities, which was up 0.45 percent.
Dollar Tree slid 11.5 percent, the most on the S&P, and Dollar General was down 1.0 percent after they gave disappointing full-year profit forecasts.
PVH fell 5.6 percent after the apparel maker said it might be hit by tariffs and reported a higher quarterly profit and raised its full-year earnings forecast.
Dialysis services provider DaVita fell 8 percent after California passed a bill that aims to curb access to insurance coverage for kidney patients.
Signet Jewelers soared 25.7 percent after the company topped sales and profit estimates and raised its full-year sales forecast.
Commerce Department data showed consumer spending increased strongly in July and a Labor Department report showed the labor market remained robust, despite a rise in jobless claims last week.
Declining issues outnumbered advancers for a 1.87-to-1 ratio on the NYSE and a 1.39-to-1 ratio on the Nasdaq.
The S&P index recorded 19 new 52-week highs and one new low, while the Nasdaq recorded 45 new highs and 18 new lows. (Reporting by Shreyashi Sanyal in Bengaluru; Editing by Shounak Dasgupta)