Intermediate position sizing caps a single stock. At the strategy level, professional quants go further — sizing every signal or asset by its statistical risk contribution to the whole book, not a flat dollar amount.
The Intermediate Position Sizing lesson covered capping any single holding's weight or sizing by risk-to-stop-loss. Risk budgeting extends the same underlying idea — "how much can this hurt me if I'm wrong?" — from a single stock to an entire multi-strategy or multi-asset portfolio, where different positions carry very different amounts of volatility per dollar invested.
The key insight: an equal dollar amount in two different assets is not an equal amount of risk. $10,000 in a low-volatility bond and $10,000 in a high-volatility small-cap stock contribute very different amounts of risk to a portfolio, even though the dollar amounts match. A risk-parity or volatility-scaled approach instead sizes each position so it contributes roughly the same amount of risk, adjusting the dollar amount to compensate for each asset's own volatility.
A common formula: position size = (target risk contribution) ÷ (asset's volatility). A more volatile asset gets a smaller dollar allocation for the same risk budget; a calmer asset gets a larger one. Applied across a whole book of strategies or signals, this keeps any single volatile bet from dominating total portfolio risk, purely because it happened to get the same dollar allocation as a much calmer one.
Three hypothetical assets with very different volatility, sized two ways from a $300,000 total allocation.
| Asset | Volatility | Equal-Dollar Size | Risk-Budgeted Size |
|---|---|---|---|
| Bonds (Low Vol) | 6% | $100,000 | $192,000 |
| Large-Cap Stocks (Med Vol) | 16% | $100,000 | $72,000 |
| Small-Cap Stock (High Vol) | 32% | $100,000 | $36,000 |
Under the equal-dollar approach, the small-cap stock (32% volatility) contributes over 5x as much risk to the portfolio as the bonds (6% volatility), despite the identical dollar size. The risk-budgeted approach instead sizes each position so their risk contributions are roughly balanced.
Enter up to 3 assets with their volatility and a total allocation — see how much each would receive under equal-dollar sizing versus risk-budgeted sizing.
| Asset | Volatility | Equal-Dollar Size | Risk-Budgeted Size |
|---|
Model: risk-budgeted weight for each asset is proportional to 1 ÷ volatility, normalized so all weights sum to the total allocation — giving each asset roughly equal risk contribution. Illustrative only, and ignores correlation between assets.
Answer all five, then hit "Check My Answers" to see how you did. Get one wrong? No problem — the explanation will show you exactly why.
Print-friendly resources to revisit, practice, and dig deeper — no login required.
You've now covered all five lessons in this track — mean reversion, momentum & factors, backtesting, regime detection, and sizing a book by risk. Two more Pro tracks await: Options & Derivatives and Macro & Cross-Asset Analysis.