Types of Long-Term Debt instruments Debenture -A long-term, unsecured debt instrument Investors look to the earning power of the firm as their primary security Investors receive some protection by the restrictions imposed in the bond indenture particularly any negative-pledge clause A negative-pledge clause precludes the corporation from pledging any of its assets(not already pledged)to other creditors. 20-520-5 Types of Long-Term Debt Instruments Investors look to the earning power of the firm as their primary security. Investors receive some protection by the restrictions imposed in the bond indenture, particularly any negative-pledge clause. A negative-pledge clause precludes the corporation from pledging any of its assets (not already pledged) to other creditors. Debenture -- A long-term, unsecured debt instrument