A written masterclass, roughly eight minutes to read. General information rather than advice. No approach described here prevents loss.
Risk is not volatility
The industry measures risk as volatility because volatility is easy to calculate. For an actual investor, risk is the chance of not having the money when you need it.
| Type of risk | What it means to you |
|---|---|
| Permanent loss | The asset never recovers. This is the one that matters most and the one volatility does not measure. |
| Volatility | Prices move about. Painful to watch, harmless if you do not need to sell. |
| Liquidity risk | You cannot sell when you need to, or only at a bad price. |
| Inflation risk | The money is intact and buys less. Cash is not risk-free, it is differently risky. |
| Concentration risk | Too much depends on one holding, one sector, or one employer. |
| Behavioural risk | You sell at the bottom. Statistically the largest destroyer of individual returns. |
The dangerous combination
Volatility only becomes permanent loss when it meets a forced sale. Almost every serious personal investing disaster is that pairing, not the volatility alone.
The short list
- A cash buffer
- The single most effective risk control available to a private investor, and the least discussed. It converts a forced seller into a patient one.
- Genuine diversification
- Across asset classes, regions and currencies. Owning twelve funds that hold the same forty companies is not diversification.
- Matching horizon to asset
- Money needed within five years does not belong in equities. This one rule prevents most disasters.
- Rebalancing
- Selling what has run and buying what has lagged, on a schedule. It enforces discipline precisely when instinct argues against it.
- Position sizing
- No single holding large enough that its failure changes your plans. Employer shares plus an employer salary is a concentration most people miss.
- A written plan
- Decided when calm, consulted when not. Its main function is to stop you improvising during a fall.
What sounds clever and usually fails
- Timing the market. Missing a handful of the best days, which cluster near the worst ones, does most of the damage.
- Piling into whatever has just performed. You are buying the past at its most expensive.
- Complex hedges bought after the fall has started, when protection is priciest.
- Watching the portfolio daily. Frequent checking is strongly associated with worse outcomes.
- Confusing a fall with a mistake. A diversified portfolio falling in a general decline is behaving normally.
Decide the rule before you need it
Write down now what you will do if the portfolio falls thirty per cent. Deciding in advance is worth more than any indicator, because the decision made during the fall is the one that costs money.
A five-minute stress test
- 1If your portfolio fell 30% tomorrow, would you have to sell anything? If yes, the cash buffer is too small.
- 2What is your largest single holding as a share of the total, counting employer shares?
- 3What proportion sits in one country or one currency?
- 4When do you actually need this money? Write the year, not "eventually".
- 5What would make you sell? If you cannot answer, you have no plan, only a position.
Documents you may also need
Understanding Private Equity Structures
How a private equity fund is put together, where its returns come from, what the fees really cost, and the questions to ask before committing.
InsightsMarket Forecast & Trends
Our standing view on rates, currencies, credit and equities — what drives each, what we watch, and what it means for the decisions in front of you.
GuidesAlternative Assets: Beyond Equities
Private equity, venture, property, infrastructure and private credit — what each actually is, what you give up to hold it, and who they suit.
This document was last updated on 1 August 2026. We publish the current version here at all times; superseded versions are available on request.
If anything on this page is unclear, write to us and we will explain it.