Wall Street index futures dropped on Wednesday and chip darling Nvidia slumped after the company flagged steep charges from new U.S. curbs on chip exports to China, fuelling worries about the fallout of an escalating trade war.

Dow, S&P and Nasdaq futures were all in the black, though slightly, even though China announced it was raising its tariffs on U.S. goods again, escalating their trade war.

Analysts are debating whether Nvidia can still manage sequential growth this year as political developments pressure revenue.