Something I learned today. Canadian Pacific Railway began issuing perpetual bonds in 1893. Issued at a time when large railroad companies, unrivaled by any other but national governments, were issuing a large number of debt instruments, CPI's bonds have no maturity date, cannot be called in by the company, and continue to pay interest to bondholders. The only way one of these century-old CPI bonds can be cancelled is if the bondholder voluntarily surrenders it to CPI. As of 2020, there is $45 million CAD outstanding in CPI perpetual bonds, which enjoy a Aa1 credit rating from Moody's, and on which CPI pays 4% annually. However, the interest payments are the least of the company's worries: Over the years, these irredeemable liabilities on CPI's balance sheet have complicated business acquisitions and blocked stock conversion plans.