A merchant bank is historically a bank dealing in commercial loans and investment. In modern British usage it is the same as an investment bank. Merchant banks were the first modern banks and evolved from medieval merchants who traded in commodities, particularly cloth merchants. Historically, merchant banks' purpose was to facilitate and/or finance production and trade of commodities, hence the name "merchant". Few banks today restrict their activities to such a narrow scope.

In modern usage in the United States, the term additionally has taken on a more narrow meaning, and refers to a financial institution providing capital to companies in the form of share ownership instead of loans. A merchant bank also provides advice on corporate matters to the firms in which they invest.