What Active Management Is Trying to Do

The global investment management industry manages approximately $120 trillion in assets. The majority of this — in developed markets, roughly 60–70% — is actively managed. Active managers claim to identify mispriced securities and generate returns above their benchmark.

But there is a mathematical certainty, stated cleanly by William Sharpe (1991), that most active managers must underperform:

The Arithmetic of Active Management: Before costs, the average actively managed dollar must earn exactly the same return as the market. This is a definitional truth, not an empirical finding. All assets are owned by somebody. If active managers as a group earn above the market, passive investors must earn below it, and vice versa. But passive investors hold the market — they earn the market return by definition. Therefore, active investors as a group must also earn the market return before costs.

After costs — fund management fees, transaction costs, taxes on turnover — active managers as a group must underperform. The only question is which specific managers are in the minority that justify their fees.

This does not mean active management is uniformly bad. It means the bar is high. An active manager must have a genuine information advantage that is real and persistent (not luck), large enough to overcome fees and costs, and that translates consistently from insight to portfolio return.

Genuine alpha is rare. But it exists. This module explains how to measure it and how to find it.