Shares of Chevron Corp. /zigman2/quotes/205871374/composite CVX -0.14% and Exxon Mobil Corp. /zigman2/quotes/204455864/composite XOM -0.81% fell in premarket trading Friday, enough to pace the Dow Jones Industrial Average's /zigman2/quotes/210598065/realtime DJIA +0.07% early decliners, as a selloff on crude oil futures /zigman2/quotes/209723049/delayed CL00 +0.50% 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 +0.20% 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 -0.83% slid TK% ahead of the open. Among other more-active energy stocks, Occidental Petroleum Corp. /zigman2/quotes/207018272/composite OXY -2.40% slipped 0.4%, Marathon Oil Corp. /zigman2/quotes/205031829/composite MRO -5.18% gave up 0.8%, Apache Corp. /zigman2/quotes/200648444/composite APA -4.53% fell 1.1% and Halliburton Co. /zigman2/quotes/210488727/composite HAL -1.96% lost 1.3%.