Sizing a Position You Intend to Hold for a Decade

A long horizon is usually presented as licence to hold more, on the grounds that time smooths volatility. The reasoning runs the other way once you account for what a decade actually contains.

What a decade contains

At historical frequencies, a ten-year holding period in this asset includes two or three declines exceeding fifty percent and at least one exceeding seventy.

It also includes several periods of eighteen months or longer during which nothing recovers and coverage disappears entirely.

Sizing for a decade means sizing for all of that, not for the average.

Why the horizon argues for less, not more

You must be able to hold through the worst of it. A position sized for a thirty percent decline will be sold during a seventy percent one. The maximum tolerable size is set by the worst drawdown, not the expected return.

Your circumstances will change. Over ten years, most people change jobs, move house, and encounter at least one unplanned expense. A position sized to your current situation may not fit the one you have in year four, and being a forced seller during a drawdown is how a temporary loss becomes permanent.

The position grows on its own. If it performs, it becomes a larger share of your net worth without any decision from you. Sizing at the limit today means exceeding the limit tomorrow.

The three numbers

The ceiling. Maximum share of investable assets this position may occupy. Written down in a calm month.

The starting size. Meaningfully below the ceiling, so that appreciation has room and so that you retain capacity to add during declines.

The floor of your liquidity. Enough held outside the volatile asset that you are never forced to sell. This is about the rest of your finances and it is the number most often skipped.

Running below the ceiling

I hold roughly half my stated maximum by default.

The gap is not idle capital. It is the thing that allows me to act during a decline when everyone else is constrained, and it is the reason I have never had to choose between a rebalance and a bill.

What changes at ten years that does not at one

Tax treatment, in many jurisdictions, for long holdings.

The custody arrangement matters more. A hardware wallet and paper backup sitting untouched for a decade will encounter ink fade, forgotten passphrases and changed circumstances. An annual restore test is not optional at that horizon.

Inheritance becomes a real question rather than a theoretical one.

The venue may not exist. Anything left at a platform for ten years is a bet on that platform’s continued operation. The working balance at the exchange I have used since 2021 exists for rebalancing rather than for storage, and the size of it reflects that.

The test I apply

Would I be able to describe this position calmly, to someone who asked, in the third month of a seventy percent decline, having heard nothing positive about it for a year?

If the honest answer is no, the position is too large, regardless of how confident I feel today. Confidence is a present-tense property and the drawdown is not.