7. How to Invest
b. Comparing stocks and understanding a stock table
Millions of shares are traded every day on the NASDAQ (National Association of Securities Dealers Automated Quotation), New York Stock Exchange (NYSE) and other stock exchanges throughout the world. Market prices often rise or fall on a minute-by-minute basis for various reasons, including business conditions, investor actions and government actions. But by the closing bell at 4 p.m. EST, every stock has had its last trade of the day. It’s the price of this last trade, called the closing price, which is quoted in the papers the next day. (Some stocks trade after hours, but the official closing price of the day does not change)
Take a look at this quick video, which illustrates the basics of stock markets, how they are measured and what makes prices change over time.