Index Funds - When a Good Idea Spreads Without Nuance

2026-01-30

Financial history loves simple heroes.

An inventor. A brilliant idea. An easy-to-repeat rule. With John C. Bogle, it all seemed to come together: the creator of index funds, the man who democratized low-cost investing, the one who supposedly proved—once and for all—that beating the market is pointless.

But this interpretation is comfortable… and misleading. Bogle never intended to create a financial religion. He proposed a defensive strategy, not a universal truth. The problem isn’t what he said. It’s what has been done with his ideas.

The real problem Bogle wanted to solve

Bogle didn’t start from a theory about the perfect efficiency of markets. He started from a human observation: • investors pay too much, • trade too often, • react poorly to volatility, • and sabotage their own returns.

Its goal wasn’t to maximize raw performance, but to minimize behavioral damage. Indexing wasn’t an ideal, but a buffer. In a real, imperfect, emotional world, it increased the probability of an outcome acceptable to the majority. Nothing more. Nothing less.

What indexing doesn’t do (and never will)

An index fund: • doesn’t analyze balance sheets, • doesn’t judge the quality of a CEO, • doesn’t correct an absurd capital allocation, • doesn’t exit an overvalued stock.

It follows. It absorbs. It amplifies.

Bogle knew this. And he said it clearly: without active management, markets cease to function properly. Prices become mechanical reflections of flows, not of economic value. Indexing isn’t an engine. It’s a wagon. It follows.

When indexing becomes dominant, the nature of risk changes.

In small doses, indexing stabilizes. In large doses, it concentrates. Bogle was already concerned about: • the concentration of voting power among a few large managers, • the dilution of shareholder responsibility, • the fragility created by synchronized flows.

This risk didn’t exist on the scale we see today. It’s very real now. When everyone buys the same stocks, at the same time, for the same reasons… the market becomes more vulnerable, not safer.

The element that slogans prefer to ignore: Bogle didn’t invest his own money exclusively in indices. He held actively managed funds, non-index exposures, and entrusted a portion of his capital to his son, an active manager. John Jr., in fact, successfully outperformed his target, the Russell 2000 index of small and mid-cap US stocks.

This was neither a contradiction nor an intellectual weakness. It was management based on a hierarchy of probabilities. For the general public: simplicity, discipline, low costs.

For private wealth management: nuance, diversification of styles, and sound judgment. The more indexing increases… the more blind spots it creates. This is where the story gets interesting.

As passive flows dominate: • the dispersion of returns increases, • indices become more concentrated, • neglected segments become less efficient.

Just as in an economy where capital is concentrated, disparities widen. Prices cease to accurately reflect information. And it is here—only here—that disciplined active management finds fertile ground. Recent data illustrates this.

According to Morningstar, by 2025, more than 8,300 out of 20,800 funds had outperformed the S&P 500. And more than 1,100 had surpassed the exceptional 28.2% return of the S&P/TSX.

This is not a promise. It is a reminder: added value has not disappeared; it has shifted.

Bogle was already applying what we now call maturity. Without the modern vocabulary, he practiced a logic that many are rediscovering: a solid index core to capture market exposure, then smaller positions holding elements from more niche categories, rigorously chosen. This isn’t a lukewarm compromise. It’s a robust structure that recognizes two simultaneous realities: average mediocrity… and marginal excellence.

And the Buffett argument?

Warren Buffett is often cited to defend universal passive investing. Ironic, considering that Buffett built his fortune with Berkshire Hathaway, a concentrated, discretionary, and deliberately active management firm. If he truly believed in universal indexing, Berkshire would be an ETF. It isn’t. It’s a conglomerate. The real, unsettling lesson from Bogle: Bogle wouldn’t tell us: buy indices blindly. He would tell us: beware of certainties that are too popular to be questioned. Even brilliant ideas become toxic when they are no longer questioned.

In finance, the real danger is never simplicity—it’s the herd mentality.