The managers running the biggest active funds picked stocks that beat the market in 2025 — and most still lagged their benchmark. A Morningstar do-nothing experiment and a body of academic research explain why active funds underperform even when the picking is good: skilled buying undone by poor selling, the hidden cost of trading, and the incentives that keep managers churning. The UK evidence points the same way.
A new working paper has documented the largest price inefficiency ever found in the stock market: a pure-news signal with a Sharpe ratio of 3.1, more than double any known factor. But the researchers used a frontier AI model, millions of news articles and institutional trading costs to find it — and the same evidence that shows markets are inefficient also shows why an ordinary investor still can't beat them.
Robin Powell
Jun 199 min read
SUBSCRIBE
Simply provide your email address to receive our regular update.
