What is the Comprehensive Risk Measure (CRM), and why was it created specifically for correlation trading portfolios?

Question

AcadiFi · Accepted Answer

The **Comprehensive Risk Measure (CRM)** was a specialized Basel 2.5 capital charge designed for **correlation trading portfolios** — primarily bespoke CDO tranches and nth-to-default baskets where the risk depends heavily on default correlations between reference entities.

**Why Correlation Trading Needed Special Treatment**

Standard VaR captures spread risk but not:
- **Base correlation skew** — the non-linear relationship between tranche attachment/detachment points and implied correlation
- **Correlation migration** — changes in default correlation that cause tranche values to move asymmetrically
- **Jump-to-default with tranche leverage** — a single default in a thin mezzanine tranche can cause losses far exceeding the name's weight in the portfolio

The IRC was insufficient because its migration/default model didn't capture the non-linear, path-dependent nature of tranched credit risk.

**CRM Requirements**

| Feature | Specification |
|---|---|
| Confidence level | 99.9% |
| Horizon | 1 year |
| Risks captured | Default, migration, correlation changes, recovery rate uncertainty, basis between index and bespoke |
| Model | Bank's internal comprehensive model, approved by supervisor |
| Floor | Max(CRM, 8% of Standardized Approach charge for same positions) |

```mermaid
flowchart TD
    A["Correlation Trading Portfolio"] --> B["CRM Model"]
    B --> C["Simulates: defaults, migrations, correlation shifts"]
    C --> D["99.9% / 1-year loss"]
    E["Standardized Approach charge"] --> F["8% Floor"]
    D --> G{"CRM vs 8% SA Floor?"}
    G -->|CRM higher| H["Use CRM"]
    G -->|Floor higher| I["Use Floor"]
```

**Worked Example**

Coventry Capital's correlation desk holds:
- $300M notional in bespoke CDO mezzanine tranches (5-10% attachment)
- $150M in index tranche hedges (CDX IG 7-10%)
- Delta-hedged with single-name CDS

CRM model output (99.9%, 1-year): **$67M**

Standardized Approach charge for same positions: **$420M**

Floor = 8% x $420M = **$33.6M**

Since CRM ($67M) > Floor ($33.6M), the capital charge is **$67M**.

Without CRM, the desk might face the full SA charge of $420M — so CRM provided significant capital relief for banks with sophisticated correlation models.

**CRM Under FRTB**

Under FRTB, the CRM is **eliminated**. Correlation trading portfolios are handled through:
- The **Standardized Approach** with specific risk weights for securitization positions
- Or the IMA's **ES component** with long liquidity horizons (120 days for exotic correlations) plus the DRC

Many banks have reduced or exited correlation trading as the capital treatment became less favorable.

**Exam Tip:** CRM is a Basel 2.5 concept — FRTB replaced it. Questions may ask you to compare the evolution from VaR to IRC to CRM to FRTB components.

For more on securitization capital, explore our FRM Part II materials.

What is the Comprehensive Risk Measure (CRM), and why was it created specifically for correlation trading portfolios?

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