Position sizing is the only free lunch in a volatile tape
Most investors spend their time on selection and almost none on sizing. At current volatility, sizing explains more of your outcome than stock picking does.
Two portfolios hold the same nine names in the same order. One returns 14% and the other 3% purely because of weight. Selection gets the attention; weighting gets the results. In a tape where a single mega-cap prints 8% daily ranges, that gap widens.
Volatility-scaled sizing
Assign each position a target risk contribution, then divide by its realised volatility. A name with 60% annualised volatility gets roughly a third of the notional of a name with 20%. When volatility rises, the position shrinks automatically — you sell into strength and buy into calm, which is the opposite of what intuition suggests.
- Measure realised volatility over 60 sessions, not intraday noise.
- Cap any single position at a hard percentage regardless of what the model says.
- Recompute monthly. Sizing drift is the most common source of unintended concentration.
This is not a return-enhancing trick. It is a survival mechanism. The investor who is still present after the drawdown gets to compound; the one who is forced out does not.
Disclosure
This article is analysis and education, not investment advice, and contains no recommendation to transact. The desk holds no positions in the instruments discussed. Figures referenced are generated from a sample dataset in this build. Read the methodology.