According to Reuters, U.S. stocks slumped on Thursday, after Apple Inc’s rare sales warning exacerbated fears that the Sino-U.S. trade war and a slowing China economy would eat into corporate profits, with weaker-than-expected U.S. factory data adding to nerves. Apple (AAPL.O) sank 8.5 percent, the biggest drag on the three major Wall Street indexes, after the company slashed its holiday-quarter revenue forecast on slowing iPhone sales in China, the first major warning with the U.S.