Passive vs. Active Investing

Why this matters

Parts 3 and 4 of this curriculum taught you how to research companies and estimate what they're worth. That's the toolkit of an active investor. Before using it with real money, it's worth knowing what you're competing against, and what the evidence says about how often active investors win. This lesson lays out both sides.

Two ways to invest

• Passive investing means buying a whole market, or a big slice of it, usually through an index fund, and accepting whatever it returns. No one decides which companies are better. It's often paired with "buy and hold": keep the funds through good years and bad.
• Active investing means choosing investments, or hiring a manager to choose them, in an attempt to earn more than the market or to take less risk. Picking your own stocks using the methods from Part 4 is active investing.

The arithmetic

Part 2's Index Funds introduced an argument by the economist William Sharpe. Before costs, the average actively managed dollar must earn the same return as the average passive dollar, because together they own the whole market. After costs, the average active dollar must earn less, because active management costs more.¹

This doesn't say that every active investor loses. It says that the winners' gains are matched by other active investors' losses, and that the whole group pays more to play. For one active investor to beat the market, another must trail it.

What the scorecards show

S&P Dow Jones Indices tracks how actively managed funds compare with their benchmarks. It reports that 79% of actively managed large-cap US stock funds trailed the S&P 500 over 2025, and 67% did over the first half of 2026, a period it described as more supportive for active managers.² Professional managers have research teams, data, and experience, and most still didn't beat a fund that simply owns the index.

Part of the explanation is how hard short-term prices are to predict. The 2013 Nobel Prize in economics recognized research showing that stock prices are extremely difficult to predict in the short run, and that new information is very quickly reflected in prices. The prize committee noted that the rise of index funds around the world is one example of how that research changed market practice.³

Suppose two funds earn 7% a year before costs. One, an index fund, charges 0.05% a year. The other, an active fund, charges 0.75%. On $100,000 over 30 years:

Yearly cost	Return after costs	After 30 years
0.05%	6.95%	About $750,600
0.75%	6.25%	About $616,400

The active fund has to beat the market by 0.7 percentage points a year, every year, just to finish even. All figures are hypothetical and before taxes.

The case for active investing

Active investing isn't irrational. Some managers and individuals do beat the market, sometimes for long periods. The same Nobel committee recognized research showing that prices can be partly predictable over longer periods of three to five years, for example because prices relative to dividends tend to fall when they're high and rise when they're low.³ And individuals have some advantages professionals don't: no pressure to match a benchmark each quarter, and the freedom to hold a few companies they understand deeply, or to do nothing for long periods.

The hard part is knowing in advance who will win. A strong record over a few years can come from skill or from luck, as Part 4's Misleading Performance Claims showed with a coin-flipping example.

A common middle path: core and satellite

Many investors don't choose one approach exclusively. They hold a passive "core," such as broad index funds, for most of their money, and a smaller active "satellite," such as a handful of researched stocks, sized by the limits from Part 5's Position Sizing. The core earns roughly the market's return; the satellite is where they apply their research, with a limited amount at stake if it trails.

Key takeaways

• Passive investing owns the market; active investing tries to beat it.
• Before costs, active investors as a group earn the market's return. After their higher costs, they must earn less.
• 79% of active large-cap US stock funds trailed the S&P 500 in 2025, and 67% in the first half of 2026.
• A passive core with a limited active satellite is a common way to combine the two.

Check your understanding

According to Sharpe's arithmetic, what must be true of active investors as a group?

1. They must beat the market, since they do research that passive investors skip.
2. They must trail the market on average after costs, since together they own it and pay more.
3. They must lose money in most years, since active investing has higher costs than gains.

An active fund has beaten its index for three straight years. What's the most reasonable conclusion?

1. The manager is skilled and will keep beating the index for years to come.
2. The fund must be taking hidden risks, since no fund can beat its index honestly.
3. It might be skill or luck; three years alone can't tell them apart reliably.

What's next

Active investors use many different styles. Value, Growth, Quality, and GARP compares the four you'll hear about most.