"The current financial crisis has clearly demonstrated that risk to the financial system can arise not only in the banking sector, but also from the activities of other financial firms, such as investment banks and insurance companies that traditionally have not been subject to the type of regulation and consolidated supervision applicable to bank holding companies,"

VOA: standard.2009.10.01

But in many cases firms do a mixture of different activities one of which is investment banking.

但是大部分情况下，公司做各种各样的业务,其中一个就是银行投资业务。

耶鲁公开课 - 金融市场课程节选