Shares of Chevron Corp. /zigman2/quotes/205871374/composite CVX -3.77% and Exxon Mobil Corp. /zigman2/quotes/204455864/composite XOM -2.56% fell in premarket trading Friday, enough to pace the Dow Jones Industrial Average's /zigman2/quotes/210598065/realtime DJIA -1.58% early decliners, as a selloff on crude oil futures /zigman2/quotes/209723049/delayed CL00 +0.82% weighed on the energy sector. Chevron shares shed 0.8% and Exxon Mobil's stock fell 0.6%, while Dow futures /zigman2/quotes/210407078/delayed YM00 -1.59% rose 19 points, or 0.1%. Crude futures dropped 3.7%, amid concerns over economic growth in China and growing worries of increasing trade friction between the U.S. and China. The SPDR Energy Select Sector ETF /zigman2/quotes/206420077/composite XLE -2.96% slid TK% ahead of the open. Among other more-active energy stocks, Occidental Petroleum Corp. /zigman2/quotes/207018272/composite OXY -0.82% slipped 0.4%, Marathon Oil Corp. /zigman2/quotes/205031829/composite MRO -2.48% gave up 0.8%, Apache Corp. /zigman2/quotes/200648444/composite APA -2.27% fell 1.1% and Halliburton Co. /zigman2/quotes/210488727/composite HAL -3.21% lost 1.3%.