Explain the process by which securities are bought and sold.

Investors generally use such financial information services as newspaper and online stock, bond, and OTC quotations to learn about possible investments. Market Indexes such as the S&P/TSX index, the Dow Jones Industrial Average, Standard & Poor's Composition Index, and the NASDAQ Composite Index provide summaries of trends, both in specific industries and in the market as a whole. Investors can then place different types of orders. Market orders are orders to buy or sell at current market prices. Because investors do not know exactly what prices will be when market orders are executed, they may issue limit or stop orders that are to be executed only if prices rise to or fall below specified levels. Rounds lots are purchased in multiples of 100 shares. Odd lots are purchases in fractions of round lots. Securities can be bought on margin or as part of short sales (sales in which investors sell securities that are borrowed from brokers and returned at a later date).