Knowing how many shares of a stock were traded on a particular day, often called volume, can be useful to investors. Luckily, this information is widely available from brokerages, news and stock information sites and stock exchanges. If you're comparing two days, it's worth checking how many shares were outstanding each day as well as how many were traded.
TL;DR (Too Long; Didn't Read)
You can consult the stock exchanges, financial news websites and brokerages to find out how many shares were traded on a specific day.
Why Volume Matters
The amount of stock traded in a particular day is usually known as volume. It can be useful to investors to track in order to see how much interest there is in the market in buying or selling that stock.
If there's a change in a stock price and a high volume of trading, many investors will interpret that change as more significant, since a bigger portion of the market is involved in transactions shifting the price. If volume itself suddenly rises, that can be a sign that something important is happening with the company that issued the stock, and it could be worthwhile to look into this. You can even look up the highest volume stocks on a particular day to look for companies that are having interesting things happen.
Look Up the Volume
Many finance research sites and brokerage stock search sites display volume information, usually in terms of shares traded per day. You can usually see this data in a chart or graph format or often download it in a format that you can load into a database or spreadsheet program of your choice.
Some stock exchange websites also provide historical volume information about the stocks traded on their exchanges that can be useful for tracking trends over time. Again, this information is often available either for viewing online or for downloading into a program, such as a spreadsheet or database, for more in-depth analysis.
Making Trading Volume Comparisons
It's sometimes useful to compare trading volume for a particular stock at different points in time in order to see when it's been unusually high or low. However, remember that the amount of ownership in a particular company can change over time due to corporate events like stock splits, where each share is replaced by a larger number of shares.
Volume data is often adjusted to compensate for a split in order to make comparisons fair. For instance, after a three-for-one split where each share is replaced by three shares, historical volumes would be multiplied by three in order to compare with present-day volumes.
Looking at Dollar Volume
Some traders and investors will also look at a measurement called dollar volume. That represents the actual dollar value (not the number) of the shares in a stock traded on a particular day. That can be useful for comparing multiple stocks or for determining a stock's liquidity, or essentially how easy it is to buy and sell the stock on the market.
Steven Melendez is an independent journalist with a background in technology and business. He has written for a variety of business publications including Fast Company, the Wall Street Journal, Innovation Leader and Ad Age. He was awarded the Knight Foundation scholarship to Northwestern University's Medill School of Journalism.