U.S. stock futures are lower as investors waited for artificial intelligence chip darling Nvidia's earnings after the bell.

U.S. stock index futures slipped on Wednesday after a sharp rally in the previous session, when easing tariff tensions boosted sentiment, as investors focused on AI bellwether Nvidia's upcoming earnings and developments on the trade front.

Nvidia is forecast to post earnings per share of $0.893 on revenue of $43.12 billion for the three months to April 31, both up substantially from last year, Investing.com data showed.