Which type of bond is characterized as irredeemable or perpetual?

Irredeemable bonds, also known as perpetual bonds, are characterized by their lack of a maturity date. This means they do not have a specified end date to repay the principal amount, allowing them to pay interest indefinitely, typically at a fixed rate. Investors in irredeemable bonds will continue to receive interest payments as long as the bond remains in force, and they have no claim to repayment of the principal unless the bond is called back by the issuer, which is not a feature of this type of bond.

In contrast, callable bonds allow issuers to redeem the bond before its maturity at their discretion, which distinguishes them significantly from irredeemable bonds. Vanilla bonds are standard bonds with fixed term lengths and simple features, while sustainability bonds are typically issued to fund projects with positive environmental impacts and have a defined maturity. Neither of these options shares the key characteristic of lack of maturity found in irredeemable bonds, reinforcing why irredeemable bonds is the most accurate choice.