In business, the trading day is the time span that a particular stock exchange is open. For example, the New York Stock Exchange is, as of 2015, open from 9:30 AM Eastern Time to 4:00 PM Eastern Time. Trading days are usually Monday to Friday. When a trading day ends, all share trading ends and is frozen in time until the next trading day begins. There are several other special circumstances which would lead to a shortened trading day, or no trading day at all, such as on holidays.