The term close refers to the end of a trading session as determined by the financial market or exchange. Traders may have the option of placing orders after the close, which is known as after-hours trading or extended hours.
As is the case with many businesses, a stock market or exchange will publish days and hours during which trading can occur. Close refers to the time after which trades are no longer executed. Notable markets, such as the New York Stock Exchange, rings a bell to signal the end of trading for the day.
The exact hours during which an exchange is open will vary by geographic region. For example, the New York Stock Exchange as well as the NASDAQ are open from 9:30 a.m. Eastern Time and close at 4:00 p.m. Eastern Time. These same markets may be open during what are referred to as pre-market and after-hours too.
Markets in the United States are also closed for trading on holidays including New Years, Martin Luther King Jr.'s Day, President's Day, Good Friday, Memorial Day, Independence Day, Labor Day, Thanksgiving Day and Christmas.