What Time Does the New York Stock Market Open?

The New York stock market is often confused with the New York Stock Exchange (NYSE), which facilitates the trading of securities. The "stock market" in the United States also includes other exchanges such as the NASDAQ and the Chicago Stock Exchange. The hours of operation of the NYSE impacts the stock market as a whole because of the volume of trades it executes and the fact that some securities are traded on multiple exchanges.

In 1871, the NYSE opened at 10:00 am. Closing times varied from 2 to 4 pm Monday through Saturday. The hours varied over time. In 1985, the NYSE set its hours of operation as 9:30 am to 4:00 pm Eastern time and ended Saturday trading. In 1991, two trading sessions were added: 4:15 pm to 5:00 pm and 4:00 pm to 5:15 pm. In 2007, the NYSE amended its rule against after-hours trading to allow specialists to trade from their dealer books between 6:30 pm and 15 minutes before the security reopened on the exchange. Most transactions still occur during the regular 9:30 am to 4:00 pm session.

The time the New York stock market opens is important because the timing of transactions impacts prices of securities traded on the stock exchange. Traders are able to make investment decisions based on prices of investments before, during and after the market opens. For example, before the market opens, analysts and traders can research investments and be prepared for an anticipated price. While the market is open, traders know that the prices are continuously fluctuating. After the market closes, traders and analysts use the ending price for the day to make projections about securities. Some investors abused their power by placing trades when other investors were not able to. For example, if a trader at a brokerage firm was able to input a trade to buy a stock after learning the ending price for the day, he would gain at the expense of other investors.

When the NYSE is open, electronic feeds of recent trading information is available to the public. The information is accompanied by a disclosure identifying any time delay between when the event occurred and when it was presented. For example, the online ticker may indicate a 2-minute delay.

Most of the trades executed on the NYSE are completed automatically electronically. Without the need for human intervention, a large volume of trades can be processed in a shorter period of time. Still, as the demand for trading increases, alternative trading venues arise.