The big U.S. banks reported today.

The boom loop we've been talking about since March is in these numbers, and in what the CEOs said about AI.

First, the numbers.

Loans are growing at double-digit rates: JPMorgan up 10% from a year ago, Wells Fargo up 11%, Citi up 12%. Deal-making is booming. Goldman's investment banking fees were up 21%.

What did they say about AI?

Goldman's David Solomon put a number on it: "Recent studies estimate that the U.S. data center build-out could require north of $10 trillion of investment through 2032, averaging roughly 3.6% of U.S. GDP annually." And he said, "demand for compute significantly exceeds supply at the moment."

Citi's Jane Fraser said higher rates won't stop it: "I don't think that higher rates is going to trump the imperative to invest there. We're not seeing a slowdown in investment in the broader AI ecosystem… There's simply not enough compute. Energy remains a bottleneck."

Wells Fargo's Charlie Scharf said "investment in AI infrastructure, high employment levels and consistent wage growth continue to outweigh the risks" of higher rates, higher oil and persistent inflation.

What are the risks to the boom loop? 

Asked whether financing will become the choke point for AI spending, Solomon said, "I don't know and nobody knows," and that there is "pressure on crowding out." He added, "There will be a point in time when this recalibrates, resets, for sure."

JPMorgan's CFO said the AI theme is now "kind of everywhere," in construction loans, working capital lines and the stock market, and that he "would be surprised if anyone, frankly, was immune" to a major change in sentiment.

Jamie Dimon said JPMorgan is "tightening up a little bit on credit."

So the loop is real. It started with the hyperscalers funding the buildout from their enormous free cash flow. Now debt is playing a growing role. And with that, the biggest risk to the boom loop is the rising cost of money.

The more money AI companies need, the more they compete with other borrowers, including the U.S. Treasury. That competition can push borrowing costs higher, which can eventually threaten returns on the AI buildout — and ultimately break the boom loop.

That said, on rates, Solomon put it simply: "a 5% 10-year treasury doesn't scare me."