Executive Summary
Goldman Sachs' departing chief equity strategist David Kostin delivers a sobering reality check on the next decade of returns, predicting the S&P 500 will deliver just 3-6.5% annually through 2035—well below historical averages. His core thesis centers on an unprecedented concentration risk: the largest 10 stocks now comprise 33% of the index, trading at 30x earnings versus 50x in 1999 and 40x in 2021. While this suggests we're not in a valuation bubble, Kostin argues investors are being compensated with bubble-level risk without bubble-level expected returns. The contrarian opportunity lies in healthcare, which he identifies as statistically the cheapest sector in 30 years on a relative basis, and middle-income consumer plays positioned to benefit from upcoming tax reforms. His most provocative insight: the AI trade isn't a public market bubble but a private market reflexivity trap, where circular vendor financing creates unsustainable growth rates that will eventually reverse. With NVIDIA insiders selling 6.8 million shares in 90 days despite strong earnings, even AI's flagship company shows management confidence cracks.
Key Insights
what David Kostin said“There is high concentration, and in a high concentration portfolio, one would expect a greater level of prospective volatility than a broadly diversified portfolio. And normally, you would think about investor being compensated for the potential above average expected volatility... But that is not the case.”
what David Kostin said“We are not in an AI bubble in the public markets. And I believe in the private markets, the availability of capital and the price is probably unsustainable, which one could take as a synonym for a bubble.”
what David Kostin said“Health care, statistically, cheapest in 30 years on a relative basis... And as the uncertainty around some of the health care policy perhaps recedes, there is an opportunity from a value perspective”
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