Goldman: We earlier identified four key macro developments that signaled potential bubble issues in the late 1990s, most of which appeared from 1998 onward: sustained investment at unusually high levels; a decline in profit margins in the macro data; a sharp rise in corporate financing needs and leverage; and a widening current account deficit. As of late 2025, those dynamics were largely absent in the AI boom.

Since then, only the first of these has changed meaningfully. Over the last six months, the investment boom has accelerated.

Tech investment as a percentage of GDP has breached the 1990 highs and has risen more sharply than it did then (Exhibit 1). Capex expectations from the hyperscalers for 2026 are now nearly 80% higher than they were 6 months ago.

AI-related investment is on track to approach the peak level of the 1990s tech investment boom within the next couple of years and could exceed it. The AI investment boom is neither as broad-based nor as long-lived as the 1990s tech boom yet (Exhibit 3), but it is matching its scale (Exhibit 4).