The trading of company stock to the public has been going on for many, many years. Over the years the supply chain for buying and selling equity stock has changed with innovations in technology. Today, the old brick and mortar environment of equity trading is being replaced by virtual trading through websites like Ameritrade, E-Trade, and Trade Station.
When a privately held company needs money to expand their business, quite often they choose to sell part of the company through a public stock offering. To facilitate this process an investment banker is most often involved helping value the company and determine the price of each share of stock. Once the value of each share of stock is determined and the amount of funds needed by the company are complete, the investment banker forms a syndicate of broker/dealers who take on the responsibility of either purchasing all the shares of stock the company has to offer or to help sell in an initial public offering.