Circle of Competence: Own Only What You Understand

I learned to play cricket on a narrow lane, and for years I could do exactly one thing: a straight drive off a ball pitched up on middle stump. That was it. Bouncers, anything outside off — I left them or got out. The boys who tried every shot they'd seen on TV looked thrilling for an over and then walked back. I scored slowly, ugly, and stayed in. Investing turned out to be the same game. The money isn't made by knowing many businesses. It's made by knowing exactly which ones you can play — and leaving the rest alone.

That boundary has a name. Warren Buffett calls it your circle of competence, and the surprising part is which half of the phrase carries the weight.

The boundary matters more than the size

Most beginners assume the goal is to learn more — more sectors, more tickers, more jargon — until you're cleared to buy anything. Buffett says the opposite. In his 1996 letter to Berkshire Hathaway shareholders, he put it plainly:

Read the last line twice. The size is not very important. What's vital is knowing where your circle ends. A small circle you respect makes money. A big circle with a fuzzy edge — where you think you understand a business but actually don't — is how people lose it. You played a shot you'd never practised.

This isn't a personality quirk of one rich American. It is, quietly, the difference between owning a business and owning a story you can't check. And in India right now, a record number of people are about to find out which one they bought. Demat accounts have crossed 21 crore as of late 2025 (NSDL/CDSL data via market reports, 2025) — tens of crores of first-timers, most of whom have never asked the one question that draws the boundary.

The one question that draws the line

Here is the test, and it is brutally simple. Can you explain, in two plain sentences, how this business makes money — and what would break it? If you can, the company is probably inside your circle. If you stall, it's outside, no matter how good the chart looks.

Let me show you the test working on two real businesses on opposite sides of the line. Neither is a buy or sell call — they're just clean examples of understandable versus hard-to-understand.

Inside the circle: Britannia

Start with one you've eaten. Britannia bakes biscuits, cakes, rusk, bread and cheese, sells them through every kirana and quick-commerce app in the country, and pockets the gap between what flour-and-packaging cost and what you pay for a Good Day. That's the whole machine. Now the numbers, so the abstraction has weight.

In FY26 Britannia did about ₹19,152 crore of sales and turned that into roughly ₹2,537 crore of net profit — an operating margin near 18.5% (Inve data, 2026). It carries almost no debt: interest paid for the entire year was about ₹113 crore, a rounding error against profit. Spread across its ~24 crore shares, that's earnings of about ₹105 per share (Inve data, 2026).

A beginner can actually reason about every line of that. Will Indians keep eating biscuits? Yes. What could break it? Flour and palm-oil prices spiking, or a price war with Parle and ITC squeezing that 18.5% margin. You can watch those things. You can even check whether management does what it says: on its Q4 FY25 call, Britannia guided that it would "get back to double-digit growth in FY26" — and that guidance was missed (Inve data, 2026). You don't need a finance degree to hold management to its own words. That's what being inside your circle feels like — you can keep score.

Outside the circle (for most beginners): Bajaj Finserv

Now a business most first-timers buy because the name is famous and the chart went up — and almost none can explain. Bajaj Finserv is a holding company (Inve data, 2026). It doesn't sell you a product; it owns slices of other financial companies — lending, life insurance, general insurance, and more — and its reported profit is a blend of all of them.

Look at what that does to the financials. In FY26 the group reported about ₹1,51,044 crore of revenue and roughly ₹19,669 crore of net profit (Inve data, 2026). Sounds clean — until you see the balance sheet carries about ₹4,29,914 crore of borrowings, and the year's interest expense alone was about ₹28,231 crore (Inve data, 2026). For Britannia, debt was a rounding error. For Bajaj Finserv, borrowing is the raw material — a lender's whole job is to borrow at one rate and lend at a higher one, while setting aside money for loans that go bad.

So ask the test question. How does it make money? "It owns parts of an insurer and a lender." Fine. What could break it? Now you need to judge whether the insurance arm has priced its risk correctly, whether the lending book is quietly filling with borrowers who won't repay, and how a single move in RBI's interest rates ripples through ₹4.3 lakh crore of borrowings. That is genuinely hard — it's why insurance and bank analysts exist as a separate species. There's nothing wrong with the company. It's simply outside the circle of most beginners, and a flat fact worth admitting out loud: I can't value an insurer's reserves either, and I'm not going to pretend otherwise.

Same exchange, same screen, same green candles. One business you can hold management accountable on by lunch. The other you'd be holding on faith.

"Boring" is usually a compliment

Notice what the easy-to-understand business looks like: biscuits. Slow. Familiar. The instinct of a new investor is to skip past it toward something that sounds cleverer — a holding company, a new-age platform burning cash on a promise of future profit, a stock three friends are "in." But the cleverer it sounds, the more often it's sitting outside your circle wearing a costume.

The mistake is rarely buying a bad business. It's buying a business you can't follow, and then discovering you have no way to tell good news from bad. When biscuit volumes slip, you'll know — you can read it in the results in plain English. When an insurer's reserving assumptions quietly drift, you won't, until it's in the price. Staying inside the circle isn't about being timid. It's about only making bets where you can keep score.

And keeping score, quarter after quarter, is the actual work of an owner. Did management hit the growth it guided? Did the margin hold? Did a commitment from last year quietly go silent? For one biscuit company you can do that by hand. For a 10–15 stock portfolio, across every concall, year after year, nobody can — which is the whole reason a tool like Inve's Promise Tracker exists: to keep the scoreboard for you so you can stay an owner without drowning in transcripts.

Where this could be wrong

Let me argue the other side honestly, because the circle idea gets abused. "Stay in your circle" can curdle into "never learn anything new" — an excuse to own three stocks forever and call laziness discipline. That's not the rule. The rule is that you expand the circle deliberately, by doing the work to genuinely understand a new business before you buy it — not by buying first and hoping understanding arrives later. Munger spent decades widening his. The circle is meant to grow. It just isn't allowed to grow by self-deception.

The lane I learned cricket on eventually got wider. I added a cut shot — after weeks of actually practising it, not in the middle of a match against a fast bowler. That's the move. Learn the shot in the nets. Then play it.

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