Stocks get halted all the time. Sometimes for news, sometimes due to a fat finger, sometimes due to market volatility. What normally happens in the case of ne

Stocks get halted all the time. Sometimes for news, sometimes due to a fat finger, sometimes due to market volatility. What normally happens in the case of news is that the stock will be halted before the news comes out and then the stock will reopen sometime after the news so that everyone has a chance to digest the news. In the case of a fat finger or market crash things are a little different. In that case trads can be undone, meaning that if you bought as the stock crashed you could get your trade busted. After the trades have been undone, the exchanges make sure there is adequate liquidity on either side of the book and trading resumes. This second case is a bitch for automated trading systems as we(the designers) don't often take this into account and even less frequently get a chance to test this case in the wild.