Initial Public Offerings generally involve one or more investment banks as «underwriters». The issuer enters a contract with the underwriters to sell its shares to the public. The underwriters then approach investors with offers to sell these shares.

A large IPO is usually underwritten by a «syndicate» of investment banks led by one or two major investment banks (lead manager). The underwriters keep a commission based on a percentage of the value of the shares they sell. Multinational IPOs may have as many as three syndicates to deal with differing legal requirements in the home country, the U.S. and other countries. Because of the wide array of legal requirements, IPOs typically involve one or more law firms.