US STOCKS-Wall St down 1 pct as cheaper yuan hits commodities
* Commodities fall as cheaper yuan boosts dollar
* Eight of 10 S&P sectors down, energy stocks weigh
* Industrials and materials stock also hit
* China uncertainty weighs on Apple, GM, Caterpillar
* Indexes down: Dow 1.37 pct, S&P 1.2 pct, Nasdaq 1.42 pct (Updates prices)
By Sweta Singh
Aug 11 (Reuters) - All three major U.S. stock indexes were down more than 1 percent on Tuesday for the first time in over a month as China's surprise devaluation of the yuan stoked fears about the health of the economy and pressured commodity-related stocks.
The yuan fell to its lowest against the dollar in almost three years following what China's central bank described as a "one-off depreciation".
U.S. crude hit contract lows, trading about $1 above its bottom for 2015. Brent, the global benchmark, was heading for its largest decline in a week. The currency move by the world's top metals consumer pushed copper and aluminum to six-year lows. Continuación...