Invest in What You Know

"The person who turns over the most rocks wins the game. That's always been my philosophy." — Peter Lynch

Lynch's most democratic idea is that an individual investor has a genuine edge over Wall Street: real-world knowledge of products and trends. A professional analyst may cover twenty companies in one sector; you move through many industries every week as a customer and observer. A busy new shop, a product people keep recommending, a supplier's order book — these are primary research.

Lynch sorted his ideas into recognisable types:

1. Stalwarts — large, reliable compounders.
2. Fast growers — smaller companies expanding quickly.
3. Turnarounds — beaten-down businesses that can be fixed.
4. Asset plays — hidden value on the balance sheet.
5. Cyclicals — bought near the bottom of their cycle, not the top.

The key discipline is to be able to explain, in one sentence, why you own something. If you cannot, you do not understand it well enough. Everyday observation is the start of research — never a substitute for it.

Illustrative example: noticing before modelling

Lynch often credited some of his best ideas to ordinary life — a product his family and colleagues could not stop talking about — which then prompted proper analysis. The point is not the tip; it is the habit of noticing, followed by doing the work.