In developed economies around the world, long-term government bond yields are climbing to levels not seen in decades.

Traditionally that's been a warning sign that investors are worried about nations' fiscal health. But in this case the AI boom is also playing a role, as Big Tech issues vast quantities of debt to buy Nvidia chips and build data centers, offering bond investors a snazzy alternative to musty old U.S. Treasury bonds and their overseas cousins.

-- In the U.S., the 30-year Treasury yield was recently 5.329%, on pace for its highest settle since 2007.

-- German and French long-dated yields are headed for their highest closing levels since 2011 and 2008, respectively.

-- In Japan, where Prime Minister Sanae Takaichi has abandoned years of fiscal restraint in a bid to juice the economy, yields are close to their all-time high.

To varying degrees, all those countries share concerns about aging populations and widening deficits. But they also face competition from tech companies issuing bonds for AI investments, which are increasingly long-dated, maturing in more than 10 years, Barclays pointed out in a research note yesterday.

"The change this year has been the scale and maturity of AI-related corporate borrowing," Barclays said.