It is typical to briefly halt trading in a stock, if a company makes an announcement (or undergoes an unexpected external event) likely to have a non-trivial ef

It is typical to briefly halt trading in a stock, if a company makes an announcement (or undergoes an unexpected external event) likely to have a non-trivial effect on its stock price. This is to allow time for significant news to disseminate into the marketplace. For this reason, you will frequently see companies make major announcements outside of trading hours.