Tumble in U.S. Stock Futures Sets Off Limit Down Trade Curb
Contract prices hit a ‘hard downside limit’ when they fall 5%
Stocks plunging worldwide on results of British Brexit vote
Waves of selling in stock futures sent S&P 500 indexes on the Chicago Mercantile Exchange into a limit-down trading curb.
The rules are triggered when S&P 500 contracts decline 5 percent from a reference price that is calculated in the last 30 seconds of trading on the previous day. E-mini futures plunged 5.07 percent to 1,999 and can’t go any lower in the overnight session.