U.S. stock futures fall more than 1 percent as China shares plunge

U.S. stock futures extended falls in Asian trading on Wednesday, tumbling more than 1 percent as plunging Chinese shares rattled investors.

S&P 500 E-mini futures were last down 1 percent on the day at 2,053.75, after dropping as low as 2,052.25.

China's share markets extended a savage correction that has clipped 30 percent off Chinese shares since mid-June, despite market support steps from Beijing.