Peter Lynch
Buy what you understand, and do the homework anyway.
Running Fidelity's Magellan Fund from 1977 to 1990, Lynch compounded at about 29.2% a year and grew the fund from roughly $20 million to more than $14 billion, making it the largest mutual fund in the world at the time.
Educational biography, not investment advice. Describing how someone invested is not a recommendation that you invest the same way. Figures were checked against public sources in September 2026.
Biography
Caddying his way in
Lynch caddied at a country club outside Boston as a teenager, listening to executives talk about their businesses. A Fidelity president he caddied for helped him land a summer internship, and he joined Fidelity full time in 1969.
Magellan, May 1977
He inherited a small, obscure fund of about $20 million. He ran it for thirteen years, reportedly holding well over a thousand positions at times and visiting or interviewing hundreds of companies a year.
Retiring at 46
He stepped down in May 1990, at the top, citing the hours and time away from his family. He has spent much of the time since on philanthropy and on writing about investing for non-professionals.
Investment style
Lynch practised growth at a reasonable price: find companies whose earnings are growing quickly, and refuse to pay a price that already assumes it. His edge was volume of research, not a secret formula.
- “Invest in what you know” — with the second half attached — The famous line is routinely truncated. Lynch's point was that everyday observation is a good source of ideas, to be followed by studying the financials. He has explicitly said he never told anyone to buy a stock just because they like the store.
- The PEG ratio — Price-to-earnings divided by the earnings growth rate. A PEG near 1 suggested a fair price for the growth; well below 1 was interesting. This single measure is his most widely adopted contribution.
- Six categories — He sorted holdings into slow growers, stalwarts, fast growers, cyclicals, turnarounds, and asset plays, and argued each needs its own expectations and its own sell discipline. Applying a fast-grower's hopes to a cyclical is a classic way to lose money.
- Tenbaggers — A handful of positions that rise ten-fold can carry an entire portfolio, which is an argument for letting winners run rather than trimming them early.
- Boring is good — Dull names, dull industries, spin-offs, and companies institutions ignore are where mispricing survives longest.
- Know why you own it — His test was whether you could explain the reason you own a stock, in plain language, in under two minutes.
The record
| Measure | Figure |
|---|---|
| Magellan annualised, 1977–1990 | ~29.2% |
| Tenure | 13 years, May 1977 to May 1990 |
| Assets at start | ~$20 million |
| Assets at departure | >$14 billion |
The honest caveats
Every approach on this site comes with the reasons it might not work for you. This one is no exception.
- Most investors in the fund did far worse than the fund. Because money poured in after strong years and left after weak ones, the average dollar invested in Magellan earned substantially less than the fund's headline return. This gap between time-weighted and dollar-weighted returns is one of the most useful lessons in the whole story, and it is about investor behaviour rather than about Lynch.
- The era helped. He ran Magellan through a powerful bull market, starting from a small asset base that let him buy positions too small to matter to larger funds.
- The workload was extraordinary. Lynch's edge came substantially from sheer volume of company research at a punishing pace. “Invest in what you know” reads as effortless only if you skip what he actually did all day.
- The slogan is dangerous when truncated. Buying a company because you like its product, with no look at the balance sheet, is precisely the behaviour Lynch has spent decades trying to correct.
Frequently asked questions
What was Peter Lynch's investment strategy?
Growth at a reasonable price. He looked for companies with strong earnings growth trading at a price that did not already reflect it, often judged with the PEG ratio, and he sorted holdings into six categories each with its own expectations.
What return did Peter Lynch achieve at Magellan?
About 29.2% annualised from 1977 to 1990, over thirteen years, growing the fund from roughly $20 million to more than $14 billion.
What is the PEG ratio?
Price-to-earnings divided by the earnings growth rate. Lynch used it to judge whether a fast-growing company's price already assumed its growth, with a reading near 1 suggesting a reasonable price.
Did Peter Lynch really say to invest in what you know?
He said it, and he has spent years objecting to how it gets quoted. His point was that familiarity is a source of ideas, not a substitute for researching the financials. He has stated plainly that he never advised buying a stock simply because you like the company's products.