Dot Com Bubble vs. AI Bubble: 2000 and 2026 Compared

The comparison finds that today’s AI-led market resembles the dot-com era on some measures but not others. The Shiller CAPE, which compares prices with a decade of inflation-adjusted earnings, stood around 41 in 2026, near its 44.2 peak in 1999. Technology stocks also accounted for a larger share of the S&P 500 - 39.4% versus nearly 35% in March 2000 - and the ten biggest companies made up about 40.6% of the index. Nvidia’s roughly $5 trillion value dwarfed Cisco’s $579 billion at the earlier peak. Yet the S&P 500’s forward price-to-earnings ratio was 18.7 in late October 2026, below its 24.4 reading in March 2000 and below recent averages.

The market’s losses also remain modest by comparison: the Nasdaq was down 6.8% from its October 2026 record at the November 4 close, versus a 77.9% collapse from 2000 to 2002. Meanwhile, AI-related investment contributed 39% of U.S. GDP growth in the first nine months of 2025, compared with 28% from comparable technology investment in 2000. That spending supports growth but makes the economy more exposed if investment slows. The AI Bubble Index remained in its “Normal” range at 63.3, though its historical-comparison core was much higher at 80.1. These indicators describe elevated valuations and vulnerability, not proof that a crash is imminent; the key tests are whether earnings forecasts hold and concentration and spending continue to rise.