U.S. index futures slumped on the final trading day of April, dragged lower alongside European and Asian markets, despite stellar economic data and blockbuster earnings as traders took a month-end breather amid a record high for the S&P 500 Index and some earnings disappointments. The dollar pared April losses, and the VIX jumped. Russell 2000 futures tumbled 1.1% and Nasdaq 100 futures dropped 0.8% after China’s antitrust crackdown weighed on Asian technology shares. Twitter plunged 13% in premarket trading after forecasting second-quarter revenue below some expectations, while Amazon's blockbuster earnings helped push the stock to all time highs, although gains were trimmed in the premarket.