Volatility is not risk
One is how much the price moves. The other is the chance of not having the money when you need it. They are related, and they are not the same.
Finance uses “risk” to mean volatility — how much a price fluctuates — largely because volatility is measurable and risk is not. That substitution is convenient and it is not quite true.
The distinction
- Volatility is the size of the wobbles. A holding that swings widely and ends higher was volatile and profitable.
- Risk, in the sense that matters, is the chance of a permanent loss, or of not having the money when you need it.
An asset that rarely moves, because it rarely trades, is not safe — its price is simply not being updated. Some of the worst losses in financial history were in things that looked calm right up until they were marked to reality.
When volatility does become risk
When it forces a sale. A falling price is a quotation until you have to accept it; at that point it becomes your outcome. Anything that forces the sale — needing the cash, borrowed money, or simply being unable to tolerate the decline — converts volatility into a permanent loss.
Which means the same volatility is a different amount of risk for two different people, depending on their circumstances and their temperament.
The practical version
- Match assets to when you need the money. Money needed in two years does not belong in something that can halve.
- Avoid leverage on volatile assets. Borrowing removes your ability to wait, which is the whole defence.
- Judge tolerance honestly. Not what you believe you would do in a 40% fall — what you did in the last one.