Loan stock refers to shares of common or preferred stock that are used as collateral to secure a loan from another party. The loan earns a fixed interest rate, much like a standard loan, and can be secured or unsecured.

A secured loan stock may also be called a convertible loan stock if the loan stock can be directly converted to common shares under specified conditions and with a predetermined conversion rate, as with an irredeemable convertible unsecured loan stock (ICULS).