John Maynard Keynes: the beauty contest, animal spirits and an economist who became an investor
The most famous economist of the twentieth century also managed money, failed at timing the market and then changed his method. His ideas about crowds and concentration, set against six real portfolios.
Who he was
John Maynard Keynes (1883–1946) was a British economist whose General Theory of Employment, Interest and Money (1936) founded modern macroeconomics. He was also a practical investor: he managed his own money, the funds of an insurance company and, from the 1920s, the endowment of King's College, Cambridge, known as the Chest Fund.
His record as an investor is a story of mistakes and learning. He was nearly ruined by currency speculation in 1920, and he lost heavily again around the crash of 1929. What he did next is the part worth studying.
The core ideas
In chapter 12 of the General Theory he described professional investment as a newspaper beauty contest in which you must pick not the faces you find prettiest but the faces the other readers will pick. Prices, in this view, depend less on what a business is worth than on what the crowd believes the crowd will believe. He also spoke of animal spirits: the spontaneous urge to act, and the optimism and fear that make investment swing in a way that cold calculation does not explain.
From this he drew a practical lesson about the long term. Most investment decisions, he wrote, cannot be based on exact calculation, and the stock market makes the problem harder because it allows everyone to change their mind every day. He saw that the same market that offers liquidity also encourages short-term thinking.
How his own method changed
In the 1920s Keynes tried to time the market by following the credit cycle and the economy, shifting between shares, currencies and commodities. It did not work well. In the 1930s he changed his approach and, as he wrote in letters to colleagues at the college, concentrated on a small number of holdings of businesses he knew well and was willing to hold through price swings, buying shares which he thought were worth more than the market price and not worrying about short-term moves. He also said that it is better to be right with a few large holdings than to spread money so thinly that you know nothing about any of it.
Later research on the Chest Fund suggests that this second approach did beat the British market over his years of managing it, although it had large swings. The honest conclusion is that his method was a reaction to failure, and that it is more notable for its change than for a single formula.
What six current portfolios show
The table shows the two sides of his experience in modern form. Duquesne, a macro investor in the spirit of the early Keynes, reads the economy and policy but turns over 23.8% of its book each quarter, while it still keeps a single large anchor, Natera at 16.6%. The investors who resemble the later Keynes hold fewer positions and change them slowly: Berkshire opens or closes about 1.0% of its book per quarter and keeps the ten largest holdings at 91.0%; Pershing Square holds ten names that behave like 6.9 equal positions.
A beauty-contest reading is also visible. Pershing Square sold almost all of its Alphabet in the quarter to March 2026 and moved into Meta and Microsoft, and in the same quarter Berkshire more than tripled its Alphabet shares. Two large investors, looking at the same company, took opposite positions in the same quarter, which is a reminder that nobody knows which view the crowd will share.
Six real portfolios side by side, from the latest filing of each investor (Form 13F, US-listed stocks only). Effective positions is the number of equal-sized positions that would be as concentrated as the real portfolio: one divided by the sum of the squared shares. Opened or closed is the average over the four quarters of half the combined share of positions that were opened or closed.
| Investor | Reported stocks | Positions | Effective positions | Largest position | Ten largest | Opened or closed per quarter |
|---|---|---|---|---|---|---|
| Warren Buffett | $299.3 billion | 26 | 8.1 | 22.0% | 91.0% | 1.0% |
| Ray Dalio | $24.4 billion | 990 | 23.9 | 16.3% | 42.1% | 5.8% |
| Bill Ackman | $13.7 billion | 10 | 6.9 | 17.6% | 100.0% | 7.0% |
| Stanley Druckenmiller | $5.2 billion | 94 | 22.2 | 16.6% | 46.3% | 23.8% |
| Seth Klarman | $5.4 billion | 23 | 13.4 | 16.5% | 74.9% | 9.5% |
| Mohnish Pabrai | $0.3 billion | 4 | 2.9 | 43.3% | 100.0% | 4.4% |
Where it is challenged
Keynes is often quoted for lines he may not have written, such as the one about markets staying irrational longer than you can stay solvent, and his record has been described more generously than the facts always allow. His warning that the stock market mixes investment and speculation is valid, but the beauty-contest picture can also be taken too far: in the long run earnings and cash flows do matter for prices, and the crowd does not always rule.
A practical objection is that concentration, which he came to favour, adds risk. A few holdings that you know well can still fall by half, and only a person with the nerve and the time horizon of a college endowment can sit through it.
What to take from it
Think about what other investors will do, but do not rely on predicting it. Be willing to admit that a method is not working and change it. Prefer a small number of positions you understand over a large number you do not. And match the horizon to the money: Keynes could hold through a bad year because the college did not need the money next month.
None of this removes the risk. It is a way of thinking, not a promise of results.
Where it meets our bots
The beauty contest has a mechanical version in our trend bots: the S&P 500 trend bot, the Nasdaq trend bot and the dual momentum bot all follow what the market is already doing instead of guessing what a business is worth, which is the logic of someone who thinks the crowd sets the price. The tactical allocation bot moves between asset classes by the same kind of rule. None of them has Keynes's judgement or his willingness to take a concentrated bet.
Their accounts are virtual and public. The guides below explain the rules and their weak points.
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