Key Highlights

● An economist warned of a potential AI capex bust around 2028.

● AI infrastructure stocks rallied strongly the same day.

● Alphabet raised its 2026 capital spending forecast.

● The comment reflects a tension between near-term demand and long-term risk.

On a day when AI infrastructure stocks rallied hard, one of Wall Street's better-known macro voices offered a sobering long view, saying he thinks the market is heading for an AI capex bust, but probably not until 2028. The remark captures a tension running through markets: the AI build-out is still accelerating, but investors are increasingly asking how long the spending can last and who will pay for it.

For now, the data point toward more spending, not less, with Vertiv soaring after reporting surging sales and orders that more than doubled, and Oracle jumping after its investor day laid out a fiscal 2030 revenue target of at least $225 billion.

The Boom Is Still On

Memory and chip-equipment makers led a fourth straight gain for the chip index, and even Fed Chair Kevin Warsh weighed in on investment, saying capital spending is not just strong, but it is broadening. After the bell, Alphabet raised its 2026 capital-spending forecast, further committing to the AI buildout.

The logic of a capex bust is familiar from past technology cycles, where companies overbuild capacity in a rush to keep up, then pull back sharply once returns fail to match the outlay, leaving suppliers with falling orders.

Why a Bust Could Follow

Hints of strain were already visible the same day, as Alphabet's free cash flow turned negative in the quarter, and the shares slid sharply in extended trading after the company missed on earnings. Fed Chair Warsh said higher rates have affected the AI infrastructure buildout and that some credit spreads have widened.

Investors, at least on this day, chose the boom over the bust, with the S&P 500 rising for a third straight gain, though breadth was narrow, with Nvidia lagging the chip rally and the equal-weight index slipping slightly.