# He Buys Stocks After They've Already Run: David Gardner's Thirty-Year Method

> Notes from Behind the Balance Sheet #63 with David Gardner: why he buys high, why 'wildly overvalued' makes him more interested, and how the 'sleep number' turns position sizing into a question you can actually answer. Educational reading notes, no stock recommendations or price targets.

Published: 2026-09-18
Locale: en
Tags: David Gardner, long-term investing, valuation, position sizing, investing mindset


![A person at dawn standing at the rail of a mountain viewing platform, following a stone stairway that climbs toward a higher ridge](/covers/behindbalance-2026-09-17-63-the-fool-david-gardner-explains-his-philosophy--cover.png)

> For unto every one that hath shall be given, and he shall have abundance: but from him that hath not shall be taken away even that which he hath.
>
> —— Matthew 25:29 (King James Version, 1611)

## What This Episode Covers

On the 17 September 2026 episode of Behind the Balance Sheet, Steve Clapham hosts David Gardner, co-founder of The Motley Fool, to talk about his book *Rule Breaker Investing* and thirty years of picking stocks.

The line I most wanted to tell a friend afterwards: he runs the standard sequence backwards. Buy low, sell high is out. He buys high and tries not to sell at all. When someone calls a stock outrageously expensive, he gets more interested. His cost basis on both Amazon and Nvidia is 16 cents, and both went up more than a thousandfold — two scorecards built on a rulebook that runs opposite to the Buffett school.

![Two stock price paths side by side. On the left, a line rises and falls; the buy sits at a low and the sell at a high, capturing only a small slice of height in the middle, while the gain after the sell runs on along a grey dashed line. On the right, a line climbs steadily to the upper right; the buy sits high up, partway along, and no sell follows, so the line keeps going off the edge of the frame.](/figures/two-orders-buy-low-vs-buy-high-en.svg)

Here are the points I took away, plus some thoughts of my own.

## The Main Points

**1. His first criterion is "top dog and first mover in an important emerging industry."** It comes first because the other five sit on top of it. He wants the company creating the industry, not the third or fourth cheapest name inside it. His framing: fish in that stocked pond and your odds improve before you've done anything clever.

**2. A stock that has already run hard is a positive signal to him.** Winners, he says, do the thing winners do — they win. The disclaimer that past performance doesn't predict future results is, in his view, wrong at the level of a single company: past performance is usually the best single indicator we have. He looks back three to nine months, and only alongside the first two criteria. Buying anything at a 52-week high mechanically isn't what he does.

**3. "There are no numbers for the things that matter most."** The quality of the CEO, where a brand sits in a customer's head, the culture, the capacity to innovate — none of it appears in the statements. One line stuck with me: there's no valuation for Apple's brand anywhere on Apple's balance sheet. Which is why, if you screen on cash flow multiples and P/E, every great company looks expensive. Hence his sixth criterion: when the market calls something wildly overvalued, he says thank you.

**4. A 55% hit rate, with more losses than most people would sit through.** He measures against beating the market, aims for 60%, lands around 55%. His own list of failures is long: Krispy Kreme down 94% (the accounting turned out to be cooked during exactly the years he recommended it), 3D Systems an eight-bagger that he sold at a 90% loss, plus GoPro and Peloton. His defence is asymmetry: the worst outcome is losing 100%, and the upside has no ceiling. Three go to zero, the fourth goes up tenfold, and he'd take that trade every day of the week.

![A zero axis runs across the chart; below it, three short bars each fall only to the same depth and stop, marked by a dashed line labelled as a floor, while to the right one bar grows upward from the zero axis, running past the top edge of the frame and ending in an arrow pointing up.](/figures/asymmetry-floor-and-no-ceiling-en.svg)

**5. The "sleep number" — how much of your net worth one holding may become.** The most usable segment in the episode. He borrows the mattress firmness dial: how large can your biggest position get before you stop sleeping? At sixty he sets his around 30%; earlier in life he ran up to 80%, and he says plainly that nobody should copy that. He adds something I hadn't heard framed this way: your partner sleeps on the other side of that bed, so it's a two-person number.

**6. He learns from what works, not from what failed.** Asked which loss taught him most, he said that when we lose money everyone gathers round to ask what we learned, and while that's worth doing, he spends far more time studying what succeeded and why. He once pulled LinkedIn's list of the companies people most want to work for and found those names went on to rise thirty to fifty times.

**7. Private investors hold a set of structural advantages.** He got this from Peter Lynch: no regulation forces you to trim an oversized position to some percentage, no client demands liquidation in an ugly month and makes you sell something you still believe in. He carries none of the professional's handicaps, and he argues that beating the market is harder for a professional manager than for a private investor who knows what they're doing.

## Going Deeper

### "It's already doubled — can I still buy it?"

This is the hesitation that shows up most often in front of a screen. Buy now and you feel like the last one in; stay out and you watch it keep going.

Gardner's answer moves "it went up a lot" from the front of the decision to the back. His order is: confirm this is the top dog in an important emerging industry, confirm it has an advantage that survives three years or more, and only then does a new high get read as corroboration — the market confirming this company is winning. Run the order in reverse and you're chasing momentum, which he says isn't what he does.

![Two columns of three ranked slots. The top slot on the left holds "Has it run up a lot", and in the right column the same question sits in the third slot, with an arc curving from the top of the left column down to the bottom slot on the right.](/figures/reorder-the-question-en.svg)

So next time, try a different question: what share of my reason for buying is "it keeps going up"? If it's most of it, I'm buying a chart. If I can say where the company sits in its industry, who pays it, and why nobody can take that away, then price strength drops to third place in the argument.

There's also a test for when this breaks: price moving while the business doesn't follow. Most of Gardner's losses look like that. 3D printing enthusiasm carried the share price until the filings showed a mediocre, low-margin business underneath; Peloton was treated as a new category until the retention numbers after the pandemic couldn't support the valuation. The way to tell is to look for the revenue structure moving with the price — customer counts, renewals, revenue per customer. Those numbers are more honest than the quote.

![Two lines start from the same point. The upper one keeps climbing to the upper right; the lower one flattens out after the midpoint, and the gap between them widens, with a vertical dashed line at the point where they split.](/figures/price-runs-business-stalls-en.svg)

### "60 times earnings — am I being conservative, or is the market crazy?"

Clapham raises Costco at 60x and that exchange rewards a slow read.

Gardner's answer: the market isn't crazy, we're using a ruler that measures part of the thing. The denominator in a P/E is reported earnings, and Costco's members renewing year after year, the staff retention, the customer's trust in the pricing — every one of those builds future earnings and none appear in this year's denominator. He points out that Harley-Davidson customers tattoo the brand on their skin and Apple owners put the logo on their cars. Which line item holds that?

![A large box stands for the value of the company. Inside it, a smaller box in the lower left encloses "this year's earnings", while the rest of the space holds scattered words such as brand, culture and repeat customers, all outside the smaller box.](/figures/what-the-multiple-cannot-measure-en.svg)

This doesn't mean multiples can be ignored. What I do is turn it into a question: at today's price, what is the market assuming this company does over the next ten years? Write the assumption as one sentence — "20% revenue growth annually for a decade, margins from 8% to 15%" — and ask whether you believe it. The benefit is that expensive or cheap becomes a claim that can be proven wrong, rather than a feeling.

And Gardner's "no numbers for the things that matter most" applies here in a specific way: before concluding the market's assumption is too rich, check whether you've left out the things that never reach the statements. The reverse holds too — if a company's premium rests entirely on a story while repeat purchases, employee retention and pricing power all look ordinary, then it's expensive in the plain sense.

### "It doubled — should I sell half and lock it in?"

"When a stock doubles, sell half and you're playing with the house's money." Gardner's response: people who followed that rule sold half the Apple they could have held for thirty years.

His alternative replaces the question. Instead of "should I sell half," ask "what percentage of my assets is this, and can I sleep at that percentage?" The first question has no correct answer. The second does, and it belongs to you. Set 25% and you act at 25%, with nothing to do at 12%. The sell-half rule knows nothing about your asset base, your age, your family, or what your partner can stomach.

![A horizontal scale from zero to one hundred. A vertical line at twenty-five splits it into two parts, the left marked "no action" and the right marked "time to deal with it", with two triangle markers on the scale at thirty and eighty.](/figures/sleep-number-scale-en.svg)

When I tried writing my own number down, the hard part was honesty. Writing 40% feels bold, until that holding drops 15% in a day while making up four-tenths of everything I own — will I sit still then? Gardner lived through Netflix losing two-thirds in six months and Amazon falling from 95 dollars to 7. He calls those years heartbreaking. He never makes holding on sound easy.

One more thing he gets right: set the number with your partner. The other half of your financial life sleeps on the other side of the bed, and one person's boldness inside a shared account is called risk.

## Worth Looking At

- David Gardner, *Rule Breaker Investing* (Harriman House) — the six traits, six habits and six portfolio principles behind everything discussed here
- Peter Lynch's books written after his Fidelity Magellan run — the origin of the private-investor-advantage argument
- Lee Freeman-Shor, *The Art of Execution* — mentioned in the episode; about what you do with a position after you've picked it
- C. Thi Nguyen, *The Score* — Gardner's book of the year, on how scoring systems quietly rewrite behaviour (GPA pushing students toward easy courses, the 100-point wine scale getting judges to rate wine without food)
- Clayton Christensen, *The Innovator's Dilemma* — used in the episode as a contrast: big incumbents shouldn't be able to turn, and Alphabet, Amazon and Apple did

## The One Thing to Take Away

Six traits, six habits, six principles — and the one I want to keep is this: **spend your time studying what succeeded, rather than dissecting what failed.**

The post-mortem is the move we were trained to make, and someone always puts an arm around you after a loss to ask what you learned. Gardner goes the other way. He looks at which companies' employees love working there, which brands customers tattoo on themselves, and invests toward that. Failure tells you which road is closed; success tells you where the road is. One eliminates, one points — and we spend far more hours eliminating.

![Five paths fan out from one starting point. Three are crossed out and closed off, one stays grey and unknown, and the last extends to the right as a thick arrow marking the direction.](/figures/rule-out-versus-point-the-way-en.svg)

Here's something I've tried that you can use this week, and it holds outside investing entirely: **pick one thing you pulled off this year — a presentation that landed, a relationship you repaired, a habit that stuck — write three lines answering "why did this work," then circle one concrete action from it you could repeat next week.**

Don't write "because I tried harder." That answer can't be repeated. Write "because I read my three opening sentences aloud twice the night before," or "because I asked what he was dealing with before I said my piece." At that grain, you can circle something and do it again.