US trading halted for 15 minutes as circuit breaker triggered By ActionForex.com - Mar 09 20, 13:42 GMT FacebookTwitterPinterestWhatsAppLinkedinEmailPrint US stocks gap lower at open, with DOW down more than -1800 pts. S&P 500 also loses -7%. The massive sell-off triggered a key market circuit breaker in morning trading. Trading is halted for minutes at 13:35GMT.