The playbook that kept active fund managers employed for decades is starting to look like a relic. Equity gains have concentrated so tightly around a small cluster of AI-related stocks that the humans trying to beat the market are instead getting beaten by it.
That’s the core tension outlined in a Bloomberg report, which describes an environment where the AI rally is “humbling the humans trying to navigate the markets it increasingly distorts.” Diversification, long considered the first commandment of prudent investing, has flipped into a liability when a handful of names account for an outsized share of benchmark returns.
The narrowing problem
The Bloomberg report emphasizes that rapid market narrowing has made traditional stock-picking strategies significantly less effective. Active managers aren’t just underperforming. They’re underperforming in a way that calls into question whether their entire approach still works in this environment.
This is a structural problem, not a skill problem. When benchmark performance is dictated by a concentrated set of AI-exposed companies, the edge that comes from deep fundamental research on hundreds of stocks simply doesn’t translate into returns the way it used to.
