S&P 500 Hits Rare Valuation Milestone as AI-Fueled Bull Run Continues

The S&P 500 has seen significant gains this year, up 14% year-to-date. If history repeats itself, 2026 could see even higher numbers, marking the fourth consecutive year of double-digit gains.

This would be reminiscent of the late 1990s, when the market experienced five years of double-digit growth. However, there's another metric that's reached a level unseen since then: the cyclically adjusted price-to-earnings ratio (CAPE) has surpassed 40 for only one other time - January 1999.

The CAPE ratio is considered a more reliable valuation metric than the average P/E ratio. Currently, it stands at nearly 41 after exceeding the 40 mark in May. This level was previously reached in January 2000, preceding three years of market losses.

The strong bull run over the past three and a half years has been driven by artificial intelligence (AI), which didn't exist as an industry before 2023. Companies like Amazon and Alphabet are planning to spend about $700 billion this year, with that figure expected to increase to $1 trillion next year.

JPMorgan Chase's Jamie Dimon noted that a large chunk of the massive spend is going to companies providing data centers, energy, and memory products. These infrastructure companies are already experiencing incredible growth, similar to the dot-com bubble that led to a boom-and-bust in 2000.