Concentration builds wealth and destroys it

Almost every large fortune was built by owning one thing.

One business, one property, one holding, one skill sold at scale. Spread across forty positions, nothing moves fast enough to make anyone conspicuous.

Almost every spectacular loss was also one thing. The same one thing, quite often — the founder whose entire net worth was the company, the family whose entire net worth was the building.

This is not two lessons. It is one mechanism with two endings, and the honest version of the topic starts by admitting that.

The two questions that actually separate the cases

Not is concentration wise. Two narrower ones.

How much of everything is in it? A position that is a fifth of your assets and a position that is nine tenths of them are not the same decision wearing different sizes. The first is a bet. The second is a life.

Can you rebuild if it goes to nothing? A person of twenty-five with a concentrated position and thirty-five years of earning ahead has an enormous hidden asset that does not appear on any statement. A person of sixty-two with the same position does not.

Those two questions move in opposite directions over a life, which is why the correct answer changes over a life, and why advice from someone at a different point on that curve is so often useless.

Something people say

“Diversification is protection for people who do not know what they are doing.”

Why it spreads

It is repeated by people who concentrated and were right, and they are the only ones still in a position to repeat anything. The people who concentrated and were wrong left the conversation, usually quietly.

The part that is true

Concentration genuinely is how most large fortunes were built. Nobody became conspicuously wealthy by holding a little of everything, and the people saying so are not lying about their own history.

Someone who built a fortune by concentrating says diversification is for the timid. What is the flaw in taking that as evidence?

They are the survivor of a selection process, and everyone who followed the same policy and failed is not available to say soThey are probably exaggerating how concentrated they really wereConcentration never worksTheir situation was different from yours

Concentration you did not choose

The dangerous concentration is rarely the one on a statement. It is the one made of things that do not look like positions.

Consider someone whose salary comes from one employer, whose ownership is in that employer, whose home is in the city that employer dominates, and whose professional network is entirely inside that industry. On paper they hold two assets. In reality they hold one, four times.

When the bad case arrives it arrives everywhere at once: the job, the holding, the house price and the ease of finding the next job all move together, because they were never independent to begin with. That is what correlation means when it stops being a statistic and turns up at your door.

Not the same thing

The building phase

Capital is small relative to future earnings. The main risk is that nothing ever grows enough to matter.

Measured in

Years of remaining earning power relative to current assets

For example

Someone whose savings equal one year of income and who expects thirty more years of it.

Chase it alone and

Diversifying so early and so widely that nothing can ever move the total, while the fees and the attention still get paid every year.

The keeping phase

Capital is large relative to remaining earnings. The main risk is that a single event undoes work that cannot be repeated.

Measured in

Cost of rebuilding the position from zero, in years

For example

Someone whose assets equal twenty years of spending and whose earning years are mostly behind them.

Chase it alone and

Carrying the concentration that built the pile into a phase where there is no time to rebuild, usually because it worked last time.

Which is which? Put each one on a side.

• A founder whose company is now most of their net worth, ten years in

  The building phaseThe keeping phase

• Someone in their twenties putting real effort into one hard, specific skill

  The building phaseThe keeping phase

• A household whose income, home and savings all depend on one industry

  The building phaseThe keeping phase

Check

What is the most useful test of whether a concentrated position has become too large?

Choose one answer

Whether losing it entirely would change the decisions available to you for years afterwardsWhether it exceeds some standard share of the portfolioHow confident you are in the specific thing you ownWhether the position has performed well so far

Check answer

Worth remembering

• Concentration raises the variance in both directions: it makes the good case better and the bad case worse, in roughly equal measure.
• The two questions that separate the cases are what share of everything is in the position, and whether it can be rebuilt if it goes to nothing.
• Concentration tends to be defensible while capital is small relative to remaining earning power, and to become dangerous as that ratio inverts.
• The most common concentration is unchosen: job, ownership, housing and network all resting on one industry behave as one position.
• Advice praising concentration reaches you through a sample filtered by the very outcome it should be warning about.