The New York stock exchange opens every weekday morning in New York at 9:30 AM and closes at 4:00 PM east coast time. Likewise if you live on the west coast, it opens at 6;30 AM and closes at 1:00 PM. It is closed on Saturday, Sunday, and any national holidays. Occasionally the market opens only half a day and will close at 1:00 PM east coast time.
The NASDAQ market keeps the exact same schedule and hours as the NY stock exchange.
If you want to buy stocks for the first time, your trade will not execute during time the market is closed. If you place your order while the market is closed, you will see that it stays pending until the market opens in the morning. Once the market is open, your trade will go through and you will get the price of your stock near or at the same price at which it opens.
If you want to make a stock trade and get immediate results, you need to make sure you place your online trade during the market hours when it is open. With online trades, your order will usually go through in less than a minute. This means that in less than a minute’s time, you will have either bought or sold shares of a stock which is quite incredible when you think about it. Before online stockbrokers and online trading, you had to pick up the phone, call your stock guy, have him place the order, have someone on the floor execute the order, and then have him call you back to give you the results.
Some people inquire about after hours trading and how to do it. This is not something that is advisable for most people because it is more complicated than the easy trading that can be done while the markets are open. After hours trading can only be done with certain brokers and your buy or sell order has to match someone else’s buy or sell order for it to be executed. After hours trading has to be set up specifically for you and this is more than most average investors will want to do.