S&P 500 CAPE Tops 40 for Only 2nd Time in 100 Years as AI Boom Lifts Valuations
Updated
Updated · The Motley Fool · Jun 30
S&P 500 CAPE Tops 40 for Only 2nd Time in 100 Years as AI Boom Lifts Valuations
1 articles · Updated · The Motley Fool · Jun 30
Summary
The Shiller CAPE ratio has climbed above 40—more than double its long-run average near 17—marking only the second such reading in over a century.
That threshold was last breached in 1999 at the dot-com peak, but today’s rally rests on profit-rich giants such as Apple, Microsoft, Nvidia, Alphabet and Amazon rather than largely unproven internet firms.
The report argues those earnings may still flatter valuations because hyperscalers’ AI capital spending boosts suppliers’ revenue immediately while much of the spending cost is recognized over time.
If that accounting lag closes as AI investment costs flow through, the market could look even more expensive without stock prices rising further.
For investors, the signal is a warning rather than a timing tool: CAPE has stayed elevated for years, so the takeaway is to avoid chasing richly valued growth stocks, not to exit the market.
With AI investment vastly outpacing revenue, are we building the future or just the next dot-com bust?
The AI boom needs trillions in hardware, but what happens when it hits the bottleneck of an aging power grid?
S&P 500’s CAPE Ratio Exceeds 40 Amid AI Frenzy: Echoes of Past Bubbles and Investor Strategies
Overview
As of June 29, 2026, the S&P 500’s CAPE ratio soared to 41.39, marking a historic valuation peak and signaling an extraordinary period for the U.S. stock market. This surge is mainly driven by the AI boom, with a handful of technology giants—Apple, Amazon, Microsoft, Meta, Alphabet, Tesla, and Nvidia—collectively powering 42% of the S&P 500’s 2025 return. Nvidia alone saw its share price jump nearly 40%, contributing over 15% to the index’s gains. The market’s remarkable performance reflects strong investor optimism in AI, but also raises concerns about sustainability and future risks.