They're not trading in securities, although they would deal in securities as a part of the underwriting process.

他们不买卖证券，虽然在经营证券,是他们承销的一个环节。

耶鲁公开课 - 金融市场课程节选

Instead it deals with financial institutions and it gets involved in underwriting securities for financial institutions.

投资银行的业务对象是金融机构,业务涉及,金融机构的证券包销

耶鲁公开课 - 金融市场课程节选

Investment banking means the underwriting of securities.

银行投资业务意味着证券承销。

耶鲁公开课 - 金融市场课程节选

investment banking does underwriting of securities.

投行做的是证券承销。

耶鲁公开课 - 金融市场课程节选