Artificial intelligence (AI) has become the dominant driver of U.S. economic growth, but its massive capital expenditure requirements are reshaping debt markets. While AI spending has kept the economy out of recession, the pivot toward debt financing is increasing the supply of long-duration bonds, putting upward pressure on U.S. Treasury yields. This unintended consequence threatens to put pressure on government finances, echoing past episodes of “bond vigilantes” but with far greater debt burdens today.Understanding the neutral rateThe “neutral rate” is the enigmatic overnight interest rate for an economy with stable inflation and full employment. The Federal Reserve sets the rate by committee. It is not a specific number.About Adviser IntelThe author of this article is a participant in Kiplinger’s Adviser Intel program, a curated network of trusted financial professionals who share expert insights on wealth building and preservation. Contributors, including fiduciary financial planners, wealth managers, CEOs and attorneys, provide actionable advice about retirement planning, estate planning, tax strategies and more. Experts are invited to contribute and do not pay to be included, so you can trust their advice is honest and valuable.In fact, it is so fanciful a concept that Wall Street analysts refer to this type of economic condition as Goldilocks — not too hot and not too cold. Yields on the longer-dated U.S. bonds are a different story. They aren’t set by committee. They are set by the bond market, which is now being impacted by the AI boom. That could ultimately mean higher rates, and that is not good news for the U.S. Treasury Department.Bond vigilantes: Past vs presentOf course, the Treasury Department is no stranger to market forces driving up yields on its long-dated debt. When inflation spiked in the early 1980s, the so-called bond vigilantes rode into town and started selling government securities, driving up rates. While the moniker is worthy of an Ennio Morricone soundtrack, it was coined by economist Ed Yardeni. Who are they? The bond vigilantes are comprised of the large institutional investors who buy long-dated U.S. Treasury Bonds. These investors have long-term time horizons and, as a result, are more concerned with the levels of national debt and budget deficits in Washington than the average stock investor. In 1981, selling by these bond vigilantes forced the U.S. long bond up to 15%. That would be catastrophic to the U.S. economy if something similar happened today.This is where AI comes in, and not in a good way. AI is the driving force in the U.S. economy today. AI is the 800-gigawatt gorilla. The elephant in every room. Yet, it is always a double-edged sword. Will AI cure cancer, or is it an existential threat to humanity?Will it solve the climate crisis, or use so much energy and water in the process that it tips the planet to the point of no return?The AI-led tech sector’s cozy relationship with Washington is starting to cut both ways, too. With overt support from the U.S. administration, AI spending has kept the U.S. economy afloat and driven the stock market higher and higher. But it could soon do the same for yields on long-term Treasuries, which would have the opposite effect — it would hurt the stock market, slow the economy and cripple the U.S. government’s ability to balance its budget.AI spending and U.S. GDPFirst, the good news: The $2 trillion of capex (capital expenditures) spent on the AI build-out since 2023. By most estimates, the AI build-out will soon account for 3% to 5% of U.S. GDP. Up to this point, the spending has come exclusively from the free cash flow of the tech behemoths behind the AI build-out. It has not forced the cost of capital higher in the general economy. Now, the bad news: These AI “hyperscalers” are now turning to the debt market to fund the estimated $5 trillion to be spent by 2030. That increases the supply of long-duration bonds on the market and puts additional upward pressure on long-term rates at the worst time possible.While the U.S. economy was in a precarious position when the bond vigilantes appeared in 1981, the U.S. balance sheet was in much better shape. In fact, the federal-debt-to-GDP ratio in 1981 was 32% compared with 126% at the close of 2025. To put that into dollars owed, the U.S. national debt crossed $1 trillion for the first time in 1981. This year, it crossed $40 trillion. The U.S. needs lower rates to keep the carrying costs of the national debt from choking off all other spending. Today, the U.S. already spends more on net interest expense than it does on defense.Treasury yields under pressureThis is what triggered Treasury Secretary Scott Bessent’s recent $6 billion Treasury bond buyback to force down the yields of the long bond.It didn’t work. To be clear, the U.S. balance sheet and deficit spending already place huge upward pressure on the yields of U.S. Treasuries. The 30-year bond was at 4.61% the day before the war on Iran began. It has moved to over 5.3% in the six months since. The U.S. 10-year bond has crossed the meaningful 5% level. But now, investors in long-dated bonds have more supply.And it is happening fast. By the end of the 1980s, corporate bond maturities averaged eight to 10 years. That drifted up to an average maturity of over 12 years during the long, zero-interest stretch following the great financial crisis. In 2026, despite higher interest rates, the average maturity of corporate debt is over 15 years, including a rare “century bond” issued by Alphabet. In all, the five largest hyperscalers have already issued $500 billion in long-term debt over the past year to help finance the AI build-out. By most estimates, another trillion dollars will be financed over the next three years.The average debt rating of the five largest hyperscalers is A to AA+. With current spreads between 60 and 100 basis points higher than equivalent U.S. government bonds, this makes the longer-issued AI-linked debt attractive to the same pension fund and insurance buyers of long-term government debt. This puts upward pressure on the yields of U.S. government long-dated bonds. Shifts in the investment-grade debt marketMeanwhile, this race to fund the AI build-out is changing the composition of the investment-grade debt market as well. In the first half of 2026, the largest hyperscalers issued $165 billion in investment-grade debt. They now account for 10% of the Bloomberg U.S. Corporate Index.Looking for expert tips to grow and preserve your wealth? Sign up for Adviser Intel, our free, twice-weekly newsletter.Although not as extreme as the concentration of this cohort in the S&P 500, growing concentration in fixed income indexes raises the risk for the overall economy. While AI-linked bonds still represent only a small part of the overall investment-grade and high-yield markets, so did telecom bonds in 1995. By 1999, on the eve of the dot-com bust, telecom represented over 20% of the index.It is happening in the high-yield debt market, too. While AI-linked credit comprises less than 2% of high-yield indexes today, it accounts for 41% of new issuances in the first half of 2026.The AI infrastructure build-out is also dominating the private credit world. By some estimates, private credit will be financing over $1 trillion of the AI infrastructure build-out in the next three years.In total, this represents a massive amount of counterparty risk throughout the financial system.Systematic risk from AI debtAI-related capital spending has kept the U.S. economy from getting cold enough to slide into recession, but not hot enough to force a rate hike for over three years. AI spending also drove stock market returns higher. But now AI could create a headwind by forcing bond yields higher. This would create a real headache for a cash-strapped U.S. government. And the Fed, which is also contending with political pressure and inflation from tariffs and war, will have to thread a needle more than usual to find that Goldilocks neutral rate in a rapidly changing environment.Related ContentWhat’s Happening in the Bond Market Right Now (And Should You Adjust Your Portfolio?)Treasury Yields Are Rising. 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AI Boom Pushes Bond Yields Higher: What It Means to Investors
