Active managers who briefly looked like they might finally have their moment earlier this year are once again confronting a familiar problem: a market rally driven by a tiny group of tech megacaps that diversified portfolios simply can’t keep up with.

The share of mutual funds outperforming the S&P 500 this year has plunged to just 28%, according to the latest data from Barclays Plc, down from over 60% at the end of February. After benefiting from a rotation out of high flying technology shares and into the broader market, stock pickers are getting left behind as money floods back into a narrow group of AI-fueled heavyweights.