Role and boundaries
An exchange organizes trading in instruments under established rules. It provides a mechanism for matching orders, discloses trading information and sets admission requirements within its role. Specific functions, however, are distributed among the venue, clearing organization, depository and market participants; they are not one universal organization.
Orders and execution
If an investor submits an order through a broker, the exchange may match it with an opposing order under the trading rules. The absence of a suitable offer means that a trade need not occur immediately. The fact that a security is listed for trading also does not guarantee sufficient demand for every volume.
Admission is not a guarantee
An exchange is not required to reimburse market losses merely because an instrument is admitted to trading. Admission is also not a recommendation to buy or confirmation that credit risk is absent. It is useful to check the trading regime, information availability, restrictions and settlement terms. The last exchange price does not always represent the possible execution price of a large trade.