An Initial Public Offering (IPO) is the process through which a privately held company offers its shares to the public for the first time and becomes listed on a stock exchange. An IPO allows a company to raise capital from a broader pool of investors while giving the public an opportunity to participate in its growth.Before going public, ownership is generally concentrated among founders, employees, venture capital funds and other private investors. An IPO changes this by creating a public market where institutional and retail investors can buy and sell shares.Companies go public to raise capital for expansion, research, acquisitions or debt reduction. An IPO can also provide liquidity to existing shareholders, increase the company's visibility and make it easier to use publicly traded shares for acquisitions or employee compensation.How does an IPO work?The IPO process usually begins with the company appointing investment banks, known as underwriters, to manage the offering. These banks help determine the company's valuation, structure the transaction, prepare the regulatory documentation and market the shares to potential investors.In the US, companies generally file a registration statement called Form S-1 with the Securities and Exchange Commission (SEC). This document provides detailed information about the company's business model, financial performance, risks, management and intended use of the proceeds. It is one of the most important documents investors examine before participating in an IPO.The company and its underwriters then establish an indicative price range based on financial performance, growth prospects, comparable listed companies and expected investor demand. During the roadshow, management presents the business to institutional investors to gauge interest and determine how much they are willing to pay.Once demand has been assessed, the final IPO price is established and shares are allocated to investors. The stock then begins trading on the selected exchange, where its price is determined by supply and demand.Primary vs. secondary sharesAn important distinction is whether the shares offered during an IPO are newly issued or sold by existing shareholders. The primary shares are newly issued by the company, meaning the proceeds go directly to the business and provide fresh capital for investments and operations. The secondary shares are existing shares sold by current shareholders, such as founders, employees or venture capital funds. In this case, the proceeds go to the selling shareholders rather than the company.IPO stocks usually experience significant price swings during their first trading sessions because the market is still establishing a fair value. An important factor is the lock-up period. Existing shareholders are often restricted from selling their shares for a predetermined period following the IPO. When these restrictions expire, earlier investors can sell their shares, often increasing selling pressure. This is one of the main reasons behind the usual underperformance of IPO stocks over the short-term.Broader market conditions generally matter more than idiosyncratic fundamentals. Strong risk appetite and favourable financial conditions generally support demand for new listings, while periods of uncertainty and tighter monetary policy can make investors more cautious. This article was written by Giuseppe Dellamotta at investinglive.com.