But here is the thing: there are few obvious natural buyers for 100-year or perpetual bonds.

BBC: Should Osborne borrow for 100 years?

Typically, buyers of perpetual bonds receive a fixed rate of return but expect the issuer to redeem the bond after several years.

WSJ: Perpetual Bond Risk Rises With US Treasury Yields

But back to the 100-year or perpetual bonds.

BBC: Should Osborne borrow for 100 years?

Analysts said perpetual bonds without a step-up clause are particularly vulnerable to rising U.S. Treasury yields, and the issuer has almost no incentive to redeem the bond when it will find only higher borrowing costs elsewhere.

WSJ: Perpetual Bond Risk Rises With US Treasury Yields

"Given that Reliance has a strong credit profile and has been a regular issuer of senior dated bonds, they are in a position to issue perpetual bonds and capture low borrowing costs for the long term, " Mr. Thakur said.

WSJ: Perpetual Bond Risk Rises With US Treasury Yields

But its trading debut came as most perpetual and long-dated bonds in Asia are declining following an uptick in yields on 10-year U.S. Treasurys.

WSJ: Perpetual Bond Risk Rises With US Treasury Yields

They are called "perpetual" because the company is under no obligation to redeem them, as is the case with most bonds.

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