What's the practical difference between regulatory and economic capital?

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AcadiFi · Accepted Answer

Regulatory capital is prescribed by Basel III/IV rules and sets a minimum banks must hold to operate. Economic capital is internally estimated to cover unexpected losses at a bank's chosen confidence level, typically reflecting target credit rating.

Conceptual differences:

(1) Confidence level: Basel IRB uses 99.9% one-year for credit risk; economic capital models for AA-rated banks target 99.97% to match historical AA default frequencies.

(2) Risk coverage: Regulatory capital addresses credit, market, and operational risk with prescribed approaches. Economic capital covers all material risks including interest rate risk in the banking book, pension risk, business risk, reputational risk, and strategic risk.

(3) Diversification benefits: Regulatory rules generally disallow cross-risk diversification. Economic capital explicitly models correlations, potentially reducing capital by 15-25% through diversification.

(4) Model flexibility: Regulatory approaches are standardized or supervisor-approved. Economic capital uses internal models that may include nonstandard distributions, copulas, and stress overlays.

Numerical example: Nordhaven Bank has regulatory capital requirement of $3.8B. Economic capital with diversification comes to $3.2B, but the bank holds the binding regulatory minimum. Without diversification allowance, economic capital would be $4.1B, suggesting the bank is actually under-capitalized relative to internal targets.

For strategic planning, banks compare RAROC using economic capital (true opportunity cost) against regulatory capital (binding constraint). Business lines whose RAROC exceeds cost of equity on an economic basis but fail regulatory hurdles get capital-efficient restructuring through securitization or sale.

What's the practical difference between regulatory and economic capital?

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