Stress Testing Frameworks Under BOU Guidelines

A credible framework begins with scenario design. Base, adverse, and severely adverse paths should be linked to identifiable risk drivers such as exchange rate pressure, inflation, commodity prices, and sovereign spreads. Scenarios need narrative coherence: supervisors can accept simplified models if the story behind the shock is credible.

Document the macro-to-micro transmission: which sectors weaken first, how collateral values respond, and where funding gaps emerge under liquidity stress. Agriculture-heavy portfolios, for example, may need commodity price channels distinct from urban consumer lending.

Avoid scenario laundry lists. Three well-documented paths beat seven superficial shocks. Each path should state starting conditions, shock magnitude, propagation timeline, and management actions assumed in response.

• Align FX paths with net open positions and foreign-currency lending shares.
• Stress interest rates jointly with economic activity—stagflation matters for NIM and credit risk.
• Document challenger scenarios prepared by risk, not only economics teams.

Not every bank needs a full structural macro model on day one. Sensitivity grids, satellite PD models, and top-down loss rate shocks can be defensible when documented honestly. The BOU generally rewards transparency about limitations over false precision.

Start with material portfolios: commercial real estate, agriculture, FX-linked corporates, and unsecured retail. Expand granularity as data allows. Use historical episodes—commodity downturns, FX spikes—as sanity checks on shock severity.

Liquidity stress deserves equal billing with credit stress. Run deposit outflow assumptions, contingent liquidity draws, and collateral haircuts alongside credit losses. Many regional failures are liquidity-first events even when capital ratios look comfortable on paper.

Reverse stress testing is increasingly important. Institutions should ask what event would make their business model unviable, then work backwards to identify early warning indicators. This is especially relevant for banks with concentrated sector exposures or heavy reliance on wholesale funding.

Documentation and governance complete the picture. Stress results should feed into ICAAP, liquidity planning, and board risk reporting. When assumptions change, the institution should be able to show who approved them, what data supported them, and how management responded.

Maintain a living inventory of management actions triggered by stress breaches—dividend restrictions, growth limits, collateral revaluation campaigns, and funding diversification plans. Supervisors want evidence that stress testing changes decisions.