SRL for [scans]: At 10:33 , when the S & P 500 December futures contract crunched to a 12 - point loss under the force of sell programs , S & P futures trading was halted and program trades on the Big Board were routed into a special computer that [scans] for order imbalances .
ARG-0: a special computer | R-ARG-0: that | ARG-2: for order imbalances