Investment banks play a critically important role in channeling capital from investors to corporations. Not only do they float and distribute new corporate securities, they also assist companies in the private placement of securities, arrange mergers and acquisitions, devise specialized financing, and provide other corporate financial services. After sketching the history and evolution of investment banking, the authors describe the structure of the industry, focusing on the competitive forces at work within it today. They explore patterns of concentration and analyze the strategic and economic factors that underlie those patterns. The authors directly examine the pairing up of investment banks with their corporate clients. They show that the market is sharply segmented, with banks and corporate clients being matched in roughly rank order, the most prestigious banks with the largest, most powerful clients, and so on. Vigorous competition occurs within each segment, but much less between them. With the industry now confronting a changing regulatory environment, a growing tendency of clients to arrange their own financing, and increasing competition both from within and from commercial banks and foreign institutions, is essential reading for anyone interested in the future of investment banking.