Four weeks after U.S. stocks buckled amid a global flight from risk assets, chipmakers touched off another bout of equities selling Tuesday after a pair of industry analysts rekindled worries that the mania surrounding artificial intelligence had gone too far.

Nvidia shares got zapped by 9.5%, wiping out $278.9 billion in the biggest loss of value ever for a U.S. stock. It is now down 14% in the three sessions since it reported earnings that failed to live up to lofty expectations. All 30 members of the Philadelphia semiconductor index sank at least 5.4%, with On Semiconductor, KLA Corp. and Monolithic Power Systems down more than 9%. The Nasdaq 100 sank almost 3.2%.

There were other reasons for the bleak start to what is historically a volatile month for stocks. Worries about China’s growth shook commodities markets from oil to copper. U.S. manufacturing data came in light and showed an uptick in prices paid, a potentially worrying sign for inflation hawks.