- The price of a stock changes from moment to moment. For stocks that are heavily traded, prices can change in less than a second. For stocks that are more thinly traded, price changes can come much less frequently. Even when the major exchanges are closed, there are various after-hours markets that continue to operate.
- Many people have the impression that a stock's price is "set" somewhere. The company that issues the stock has no say in the price of its stock, nor do the exchanges in which the stock trades.
- Because a stock's price is always changing, especially when the major markets are open, any specific stock price is only useful when compared to the time that price was set. The most commonly quoted stock price is the closing price.
- A stock's price is nothing more than a report of the price at which a trade was made. For each stock, there is a bid (the amount a buyer is ready to pay) and an ask (the amount a seller is willing to take). Whenever an investor accepts either price, a trade occurs. The price at which the trade occurs becomes the stock's new price.
- A stock's price is sometimes influenced by a trade before the trade is completely finished. An order for several thousand shares of stock will likely result in the price moving up before all the shares have actually been bought. This is sometimes called moving the market.
