Is risk parity just inverse-vol weighting, or is there more to it?

Question

AcadiFi · Accepted Answer

Inverse-vol weighting is often a convenient shortcut, but true risk parity is about equalizing each asset's contribution to total portfolio risk. Once assets are correlated, standalone volatility is not enough. An asset with low individual volatility can still contribute meaningfully to portfolio risk if its covariance with other assets is strong.

Suppose Northfield Multi-Asset allocates between bonds and equities. If bonds are much less volatile, inverse-vol logic will naturally assign them a larger weight. But that does not guarantee equal risk contribution unless the covariance structure also supports it. True risk parity checks marginal contribution to risk and adjusts weights so each sleeve contributes the intended share.

```mermaid
flowchart LR
  A[Asset volatilities] --> B[Initial weights]
  C[Covariances] --> D[Portfolio risk]
  B --> D
  D --> E[Risk contributions by asset]
  E --> F[Rebalance toward parity]
```

So the exam answer is usually: inverse-vol may approximate risk parity in simple cases, but the full concept depends on portfolio covariance and risk contribution math. That is why exam questions on parity often become covariance questions the moment more than one asset is involved. If the question mentions correlation, assume you need the richer version rather than the shortcut. Practice more in our FRM question bank.

Is risk parity just inverse-vol weighting, or is there more to it?

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