Which of the following are secured by a corporation's assets EXCEPT?

Convertible bonds are a type of debt security that grants the bondholder the option to convert their bond into a predetermined number of the issuing company’s equity shares. While they are typically treated like other bonds in that they pay interest and have a maturity date, they are not directly secured by the company's assets. Instead, their value is derived from both the bond and the equity characteristics, as bondholders have the potential to benefit from the appreciation of the company's stock.

In contrast, mortgage bonds, equipment trust certificates, and collateral trust certificates are all secured by specific assets of the corporation. Mortgage bonds are backed by real property, equipment trust certificates are secured by specific pieces of equipment, and collateral trust certificates are secured by financial assets such as stocks or bonds. The nature of these securities places a direct claim on tangible assets, providing additional safety to bondholders in the event of default.

Therefore, distinguishing convertible bonds from these other types of secured bonds is crucial for understanding the implications of various types of corporate financing and the risks involved for investors.