IPO, is the first sale of stock by a company to the public. A company can raise money by issuing either debt or equity. If the company has never issued equity to the public, it's known as an IPO. Why do the company go public? The existing private shareholder might want to make an "exit" and sell their shareholders to public. The company might want to make an expansion or an acquisition or to have some more money in the bank Both the combination of the above point.