very few years, the century bond returns — not exactly with a bang, but with a new, shiny calculation involved. 

As reported by the FT and Bloomberg last month, Google's parent company has been busy tapping the bond market for everything from 3-year to 50-year bonds in several major markets (US, Switzerland, UK). Now it's trying for the ultimate prize: a century bond.

Century bonds are exactly what they sound like: a bond, often issued by a government or a long-lived institution like a university, that runs for a hundred years, often at interest rates somewhat above prevailing market rates or reference rates. For the issuer, they make a ton of sense, generationally and actuarially: They receive funds for investments right now, lock in financing costs for a long time, and face no financing rollover risk. 

It's more of a puzzle why buyers show up for these issuances, especially since the market participants have very recent examples of being seriously burned. As a bondholder of extremely long-dated bonds, you're always living in financial terror, waiting for rates to rise and inflict multiplied damage on the market value of your investment. Since bond prices move inversely with interest rates, the effects are more pronounced the further into the future — the longer-dated — the bond is. The loss of market value on a hundred-year bond when interest rates increase is far greater than on a ten- or two-year bond. When it does, this "dangers of duration," as FT journalist Robin Wigglesworth has called it, completely undermines your finances for decades on end.

The last two times century bonds popped out of academic obscurity, they got a well-deserved bad rap. In the 1990s, several large companies tried them — and locked in steep and expensive rates in the five-percent region while interest rates kept falling toward zero for decades. In the late 2010s, with ZIRP dominating the world's financial markets and trillions of mostly government debt traded at negative yield, we started seeing new players dusting off this old idea, since money now was just so cheap to be had: Universities like UPenn, Virginia, Oxford, and Rutgers took in funds for a hundred years in the two to four percent range. Then the opportunistic governments (including Ireland, Belgium, Mexico, Argentina) also successfully placed century bonds at eye-poppingly low rates. The most extreme participant was Austria, whose perfectly timed century bonds — of 2.1 percent in 2017, and then 0.85 percent and even zero percent right on the cusp of the 'rona inflation — saved its taxpayers a fortune. 

Logic alone dictates that if you sell debt due in 2120 for zero percent or 0.85 percent a year, and then CPI (and thus your incomes and tax revenues) rise to upward of 10 percent for a few years, you're doing great. Indeed, bond math logic made that exercise even more painful, with some of these placements trading at cents on the euro a few years after issuance, vaporizing bondholders' money. 

Enter Big Tech: The AI Investment Needs Meet Underwater Pension Systems

With Alphabet/Google's placements in November, and now its Swiss franc and sterling placements, it's the first time a big tech company has dared to come back to this perilous market since the 1990s. 

What's so odd about this hunger for long duration is that in the 2010s and during the pre-inflation pandemic years, at least bond investors collectively were starved for yield, ready to do anything to eke out a few extra basis points of return. In 2026, there are still positive yields to be had. The mystery, then, is not why Google issued but why investors rushed in.