Source: Fortune.com
Summary
Analysts warn that the AI-driven stock market boom may be nearing its end, with the S&P 500 expected to peak in 2026 before a 21% drop in 2027. James Reilly of Capital Economics highlighted signs of a late-stage bubble, including high valuations, unsustainable earnings growth, and declining free cash flow for AI companies. He also noted record equity issuance and market concentration. Ruchir Sharma of Rockefeller International warned that a 10-year Treasury yield above 5% could trigger a crash by making AI projects harder to fund. Yardeni lowered his confidence in a continued bull market, citing rising bond yields and oil market volatility.
Our Reading
The numbers tell one story.
High valuations mirror the dotcom era.
Earnings growth is unsustainable.
Free cash flow for AI companies turns negative.
Market concentration is extreme.
Equity issuance is a bubble signal.
Author: Evan Null
AI-Driven Market Boom
The AI-driven stock market boom has been a major driver of gains in 2026, with investors enjoying the final months of the rally. However, analysts are warning that the boom may be nearing its end. James Reilly, senior markets economist at Capital Economics, reiterated an earlier forecast that the S&P 500 could end the year at 8,250, up 7.7% from Friday’s close, before plunging 21% to 6,500 by the end of 2027.
Warning Signs of a Bubble
Reilly flagged several indicators that suggest the market is in a late-stage bubble. Stock valuations are consistent with a late-stage bubble, with the S&P 500’s cyclically adjusted price-to-earnings ratio close to its dotcom peak. Forward 12-month earnings-per-share growth for the S&P 500 is also in line with the dotcom bubble’s peak. Additionally, the sustainability of AI investment is in doubt, as the combined free cash flow for top AI hyperscalers is expected to turn negative in 2027.
Market Concentration and Equity Issuance
Market-cap concentration of indexes in fewer stocks is at extreme levels, and that narrowness is often associated with unsustainable rallies. Equity issuance is also booming, with a pipeline of IPOs and follow-on offerings. Reilly noted that such activity has historically signaled a bubble’s end is just months away, not years. This trend is consistent with previous late-stage bubbles.
Interest Rates and Debt Concerns
Ruchir Sharma of Rockefeller International warned that a 10-year Treasury yield breaching 5% could trigger a crash by making AI mega projects harder to fund. Rising borrowing costs would hit the AI boom in different ways, including fewer bond issuances and trouble issuing new equity. Sharma also pointed out that the U.S. is more addicted to debt now, with the debt burden exceeding 100% of GDP, making debt-servicing costs much higher.
Market Sentiment Shifts
Even staunch bulls are getting more anxious. Wall Street veteran Ed Yardeni lowered the odds of his “Roaring 2020s” stock market scenario for the rest of the decade from 80% to 70% and raised the odds of a bearish outcome from 20% to 30%. Yardeni cited recent developments in the oil and bond markets as unnerving, signaling a shift in market sentiment. Analysts are increasingly cautious about the sustainability of the AI-driven rally.
