HLG jumped 2020101.92% instantly after market open on 11/08/2017. all those short sellers margin call had been triggered, what would happen to them? will the broker closed their position at such incredible price?
that is not the answer for the question. anytime there are short sellers and buyers for various reasons.
Hailiang Education Group Inc. (HLG) ? Stocks can't instantly jump that much due to the circuit breaker mechanisms. Look up LULD. If you see such on your charts, it's almost certainly a data error. Plus if any clearly erroneous trades do happen, they probably get busted (undone).