Definition - What does Investment Banker mean?
Investment Banker is a financial institution that is in the business of raising capital for companies and municipalities by underwriting securities.
Testopedia explains Investment Banker
When a company decides it needs to raise money it may consider selling it's ownership to the public i.e.: going public. If the company decides to issue securities to the public it will likely hire an investment banker, who is a broker dealer specializing in public offerings. The investment banker's job is to advise the company on how to raise money, file the paperwork with the regulators and states and sell the securities to the public.