AllianceBernstein Warns of Extreme AI Market Concentration

AllianceBernstein analysts report that modern equity markets have reached extreme levels of concentration, leaving several US and global indices heavily exposed to a small number of companies. The Russell 1000 Growth Index currently shows an exposure of 57.2% to its top 10 holdings.

AI infrastructure stocks now drive nearly half of the S&P 500 earnings per share growth. The firm warns that this trend creates correlated risks, suggesting that investments by hyperscalers in AI may outpace actual cash flows. This imbalance could lead to inflated demand within the AI ecosystem and a lack of capital discipline.

In response to these risks, the firm advises portfolio managers to ensure that any underweights in mega-cap technology holdings are intentional. AllianceBernstein recommends that these decisions be based on fundamental analysis, valuation, and cash flow rather than accidental omissions.