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Why active funds underperform even when the manager picks well

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.

Robin Powell

A living room in the evening with a financial news broadcast playing on a wall-mounted television, a phone lying face-down on the sofa arm and a mug of tea on the side table

The 'biggest market anomaly ever found' — and why you still can't beat the market

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

Investor studying an AI assistant on screen, an image of cognitive surrender in financial decision-making

Cognitive surrender: what AI is doing to investors' judgment

AI now sits beside roughly a third of British retail investors as they make money decisions. New research from Wharton, MIT and a Nobel laureate puts a number on what it's doing to their judgment: confidence rises by nearly 12 percentage points, even when the AI is wrong half the time. The researchers call it cognitive surrender — and the investors most prone to it are the ones least likely to notice.

Robin Powell

May 288 min read