Topic: Investment · Type: Evergreen · Reading time: ~8 min

Over the past 100 years, roughly 4% of listed U.S. stocks have generated all of the stock market's net wealth creation. The other 96% collectively did no better than sitting in cash. That single finding, from Arizona State University professor Hendrik Bessembinder's landmark study covering every listed U.S. stock since 1926, is the cleanest explanation for why index funds vs picking stocks is not really a close debate — even if it feels like one.

This post is not going to tell you that stock picking is for idiots. It is going to show you exactly what the data says, where the standard arguments break down, and what an honest answer looks like for someone trying to build wealth without losing years to a strategy that quietly doesn't work.

The problem with picking stocks isn't skill — it's math

Most conversations about index funds vs picking stocks treat it as a question of talent. Can you find good companies? Do you have the discipline to hold? Can you read a balance sheet?

Those things matter, but they are secondary to a structural problem most people never encounter: stock returns are not distributed evenly. They are brutally skewed.

Bessembinder's research — updated through 2025 — finds that the majority of individual stocks underperform one-month U.S. Treasury bills over their full listed lifetime. Not the market. Treasury bills. The boring short-term government bonds that barely beat inflation. More than half of all stocks listed since 1926 have delivered worse lifetime returns than that. And the top 0.3% of companies account for roughly half of all net wealth creation in the entire U.S. market's history.

What this means in practice: when you pick an individual stock, the base rate odds are already against you before you've done a single hour of research. With ten stocks in a portfolio, there is approximately a two-thirds chance that none of them belongs to the small group of companies that drive long-term market returns.

Worth knowing: According to the Bessembinder study, just 86 stocks have been responsible for $16 trillion in stock market wealth creation — half of the total generated since 1926. Apple alone accounts for nearly $4.7 trillion of that, roughly 6% of all U.S. market gains ever recorded.

This is the mathematical case for broad market index funds. Not that stocks are bad — they are clearly the most powerful wealth-building tool available to ordinary investors — but that concentration is the enemy, and index funds are the most reliable solution to it.

What the professional fund manager data actually shows

If skewed stock distributions were the only problem, a clever professional with the right models might still thread the needle. So what does the data say about people whose literal job is picking stocks?

The S&P Dow Jones SPIVA (S&P Indices Versus Active) scorecard is the most widely cited measurement of how professional active funds perform against their benchmarks. It is published twice a year and covers fund categories globally. The findings are consistent across decades and geographies:

  • At one year, 65% of U.S. large-cap professional managers trail the S&P 500
  • At five years, 76% are behind
  • At ten years, 84% have underperformed
  • At fifteen years, approximately 91% have fallen short

The most recent Morningstar active/passive barometer (July 2024 through June 2025) found that just 33% of actively managed funds beat their average index counterparts — a drop of 14 percentage points from the prior year, during a period of significant market volatility when active managers are supposedly at their best.

The kicker is survivorship bias. These figures already look bad, but they understate the true failure rate. Funds that perform poorly tend to close or merge into other funds. When a fund disappears, its poor track record is quietly removed from the historical average. The data you see is the cleaned-up version. One study found that survivor bias inflates reported active fund returns by around 1.6% per year — a gap that, compounded over a decade, amounts to a very large number.

Importantly, a Morningstar analyst study found that professional managers were not necessarily worse stock pickers than the market on a hit-rate basis. About 50% of their individual picks outperformed. The problem was weighting: if a manager underweighted the biggest stocks driving the index (think Nvidia, Apple, Microsoft in recent years), it barely mattered how many mid-sized picks worked out. The index wins not because of its average stock, but because it automatically holds the enormous winners at full weight.

The fee drag that doesn't look like much until it ruins everything

There is a third factor that is easy to underestimate: the cost of active management compounds against you in the same way returns compound for you.

A globally diversified index ETF tracking something like the MSCI World typically carries an annual total expense ratio (TER) of around 0.15–0.20%. Many popular index funds now charge as little as 0.03–0.07%. An actively managed equity fund charges closer to 0.75–1.5% in most markets, sometimes more.

That sounds like a small difference. It is not. On a £50,000 portfolio growing at 7% annually, paying 1.2% per year in fees instead of 0.2% costs you roughly £38,000 over 20 years. Not in absolute return loss — in fees alone. The fund manager extracts that money regardless of whether the fund outperforms.

This is why Morningstar's research found expense ratio to be "the most dependable predictor of fund performance." It is one of the very few variables an investor can control with certainty before investing a single pound or dollar. Lower cost is guaranteed to be reflected in your returns. Outperformance is not.

For anyone comparing how compound interest works over long periods, the cost dimension operates in exactly the same way — silently, in the background, for decades.

When stock picking isn't irrational

The honest answer is that stock picking is not irrational for everyone. There are a few cases where it makes legitimate sense.

You genuinely have an informational edge. Rare, but real. A pharmaceutical researcher who understands clinical trial data better than the average analyst, a software engineer who can assess a product's technical moat — these are areas where knowledge translates to edge. Bessembinder himself acknowledged this: markets require active participants to remain efficient. Some people do have comparative advantage.

You find it genuinely rewarding. This is undersold. Researching companies is intellectually engaging for a lot of people. If you enjoy it — if it makes you more financially engaged overall and doesn't tempt you into bad decisions — then treating a small slice of your portfolio (commonly suggested as 5–10%) as a stock-picking fund is a reasonable choice, as long as you track performance honestly against a benchmark.

You want very specific exposures. Index funds struggle to replicate certain ethical constraints or thematic bets. If you want to own only renewable energy companies, or explicitly avoid certain industries, individual stocks or specialist sector funds give you control that a broad market index cannot.

What is irrational is picking stocks with the expectation of reliably doing better than a broad index over 10–20 year periods. The data says the overwhelming majority of people — including professionals with better tools and more time — don't manage it.

What this means for you

The conclusion the data points to is not "never look at an individual stock." It is more specific than that: for the core of your portfolio, meant to build long-term wealth, a low-cost globally diversified index fund has a structurally better chance of a good outcome than the alternatives.

A practical framing: treat index funds as your default, and active strategies — whether personal stock picks or actively managed funds — as something you need a clear, specific reason to add on top. "I think this company is good" is not a specific reason. "I have genuine expertise in this sector and can commit to tracking my performance rigorously against an index" is closer.

The broader point about building a diversified portfolio from scratch is not complicated: own a lot of different things, keep your costs as low as you can, and give it time. The market's gains are concentrated in a tiny fraction of stocks, and index funds are the only vehicle that guarantees you hold them — whatever they turn out to be.

Nobody rings a bell when Amazon is at $18 and you're standing at a crossroads. But the index fund already owned it.