The principal purpose of an investment bank (and of investment banking in general) is the underwriting of new securities issued by an investment bank's clients. An investment bank may also provide other services, such as professional advice, working with mergers & acquisitions, and private wealth management.
Traditional "investment banking" refers to financial advisory work. For example, a big corporation might ask for the bank's help if it wants to borrow money in the bond markets, or float itself on the stock market, or buy up another company. In this capacity, the investment bank acts as an impartial adviser - like a solicitor or an accountant - using its expertise to help its client in return for a fee. But investment banks also do something else quite different - they deal directly in financial markets for their own account. An investment bank's "markets" division makes money by buying financial assets from one client, and then selling them to another - often with a hefty mark-up.
1. Bank of America Merrill Lynch investment banking division of Bank of America. It provides services in mergers and acquisitions, equity and debt capital markets, lending, trading, risk management, research, and liquidity and payments management. It was formed through the combination of the corporate and investment banking activities of Bank of America and Merrill Lynch following the acquisition of the latter by the former in January 2009.
In 2011 Bank of America Merrill Lynch achieved the second-highest revenues of any investment bank worldwide (after J.P. Morgan & Co.), with a global market share of 7.4 per cent.
2. Barclays Investment Bank is a British multinational investment bank headquartered in London, It provides financing and risk management services to large companies, institutions and government clients. It is a primary dealer in U.S. Treasury securities and various European Government bonds.