An issuer (of a debt instrument or a similar types of instruments) is an entity (or a market player such as a bank, a financial institution, a government, etc.) that creates marketable financial instruments either based on a type of debt or by pooling financial assets (loans, securities, etc.) and creating new securities, in the form of, or corresponding to different tranches, etc. The issued securities (known as debt instruments or securitized products) will be sold to investors as an opportunity or means for earning a profit.

An issuer is generally any entity that issues securities to the market, including stocks, bonds, notes, MBSs, etc.