Key Takeaways:
Bank of America’s chief strategist sees a clear breaking point for the market’s AI-driven rally, and it’s just 2 basis points away.
A self-reinforcing “Boom Loop” driven by massive government spending and artificial intelligence investment is powering the current U.S. stock rally, but the cycle could abruptly reverse if the 30-year Treasury yield breaks above 5 percent, according to Bank of America. The warning comes as the long-bond yield hovers near 4.98 percent, putting markets on edge.
"Once the 5% line is effectively breached, the gates of doom will begin to open," Michael Hartnett, chief strategist at Bank of America, said in his May 3 report. He described the 5 percent level on the 30-year U.S. Treasury as a "Maginot Line" for markets, which he expects to hold, but warned of a fundamental reversal if it fails.
The boom has been fueled by a 75 percent expansion in nominal GDP projected between 2020 and 2027 and a 60 percent increase in government spending since 2020. AI-related investment alone accounted for about 75 percent of U.S. GDP growth in the first quarter. This surge coincides with U.S. national debt reaching $31.27 trillion, surpassing the nation's $31.22 trillion GDP for the first time in peacetime since World War II, according to recent data.
The critical question is whether rising financing costs will choke off the boom. A break above 5 percent in long-term yields would dramatically increase borrowing costs for corporations and consumers. This could derail the AI investment spree and upend a housing market that has shown surprising resilience to mortgage rates that have already climbed back above 6.5 percent.
Hartnett’s "Boom Loop" thesis rests on two powerful, interconnected forces. First, unprecedented fiscal expansion, with U.S. government spending climbing 60% since 2020 to combat inequality and de-globalization. Second, a technological revolution in AI that is driving immense capital investment.
This combination has lifted U.S. nominal GDP from $20 trillion in 2020 toward a projected $35 trillion by 2027, a 75% expansion in just seven years. The impact is clear in recent data, with AI-related investments contributing three-quarters of the 2.0% GDP growth in the first quarter of 2026. While this has been a boon for stocks and commodities, it has pressured bonds amid an inflation rate that has settled near 4%, double the pre-2020 average.
The market's strength is being tested against a backdrop of deteriorating fiscal metrics and persistent inflation. The Consumer Price Index rose 0.9% in March, bringing the annual inflation rate to 3.3%, driven by a 12.5% year-over-year jump in energy costs.
This environment puts the Treasury bond market at the center of the narrative. The 30-year yield, currently near 4.98%, is testing the 5% line Hartnett views as critical. Historically, the end of boom cycles is marked by sharp yield increases, such as the 230-basis-point jump in Japanese government bonds in 1989 or the 260-basis-point move in U.S. Treasuries in 1999.
Despite the U.S. debt-to-GDP ratio crossing the 100% threshold, the Treasury is expected to keep its bond auction sizes steady for now, leaning on strong demand for short-term bills. However, analysts warn that prolonged reliance on T-bills increases exposure to interest rate volatility, and a definitive break of the 5% barrier on long-term debt could force a painful reckoning.
This article is for informational purposes only and does not constitute investment advice.
