Global stock markets tumbled on Friday as fears mounted of a collapse of the Big Three US automakers after the US Senate refused to throw them a financial lifeline, traders said. Share prices plunged in Asia and in morning European trade after hours of late-night negotiations among US senators on a bailout of the troubled industry collapsed. The dollar in turn fell sharply, hitting a 13-year low against the yen. "It's a very bad sign. US stocks will likely nosedive," said Yasutoshi Nagai, chief economist at Daiwa Securities SMBC. Wall Street will reopen at 1430 GMT after losing 2.24 percent on Thursday.