Even though the New York Stock Exchange used to maintain a limited set of business hours on Saturdays, stock market hours changed in 1952 to align with the traditional workweek as we know it today. But with technology like the internet and mobile devices, traders can buy and sell stocks at any time, day or night. However, these trades will remain unofficial until day trading resumes.

Many stock traders research investments during the weekend.

Is the Stock Market Open on Weekends?

The Nasdaq and the New York Stock Exchange, the two largest stock exchanges in the United States, operate with hours similar to those of a standard bank. These stock market hours run from 9:30 a.m. to 4 p.m. Eastern time during the workweek, Monday through Friday. The Nasdaq and the New York Stock Exchange also offer extended times for after-hours trading on weekdays, which lasts from the close of standard stock market hours until 8 p.m.

What Is the Stock Market Friday Effect?

The stock market Friday effect, also called the weekend effect, is a well-studied pattern in stock trading. According to research, the average return, such as an amount of profit or dividends, tends to be higher on Fridays than it is on Mondays. The Friday effect also shows stock prices fall on Mondays if they had risen the previous Friday.

Some analysts attribute this phenomenon to company behavior. Large companies tend to announce bad news on Fridays, giving the stock market little time to react before the end of the trading day. Other analysts say that the phenomenon could be linked to a difference in optimism between the two weekdays. In other words, the stock market gets a case of the Mondays just like everyone else.

Can I Buy and Sell Stocks on the Weekend?

Though the Nasdaq and the New York Stock Exchange trading floors close at 4 p.m. on Friday and remain closed until 9:30 a.m. on Monday, many investors engage in after-hours trading. This is made possible through online portals and apps that allow traders to schedule the buying and selling of shares.

Even though it may appear that these investors are trading while the stock market is closed, their trades won't go through until the workweek begins, unless they're trading through a foreign market that's open at that time. Because of this lag time, after-hours trading can be risky. Prices in after-hours sessions aren’t official, so after-hours trading is generally left to traders only buying and selling small quantities of stock.