IPO advisory (for an 'Initial Public Offering') is a financial service offered by an investment banks to assist a company in the process of listing on a public exchange. This specialist IB service provides underwriting services, coordinates the efforts of the underwriting syndicate, assisting the company in preparing the registration statement, conducting the due diligence effort, providing the initial draft of the underwriting agreement and lock-up agreements as well as leading the selling efforts. With typically the “underwriter” is the investment bank who buys the shares from the company and resells them to the public. Typically the “bookrunners” are also called lead underwriters. For big IPOs they also can also have co-managers, who may assist with retail distribution.