A company goes public by making an initial public offering, which means that it offers shares of its stock to the public for the first time. A bank usually will underwrite the sale and help determine how much the shares should cost and how much of the company should be sold. It will buy those shares and sell them to investors. The company and the bank can meet with investors after the necessary paperwork is filed to announce the terms of the IPO and take orders for shares. Once the initial shares are allocated, the company can start trading on a securities exchange.