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FRM Exam Part II · Stress Testing Banks

Stress Testing Scenario Design and Selection for Banks

Updated 11 October 2026 · Fact-checked

Scenario design is choosing the shocks a bank tests itself against. You pick a scenario type (historical, hypothetical, macroeconomic or reverse), set severity and plausibility, link shocks to the bank's own vulnerabilities, and check results against capital and risk appetite. Reverse testing starts from failure and works backward.

Understand Stress Testing Scenario Design and Selection

A stress test asks one question: what happens to the bank if conditions turn bad? The answer depends entirely on the scenario. A weak scenario gives false comfort. A scenario that is too extreme gives numbers nobody acts on. So design is the core skill.

There are four main scenario types.

  • Historical scenarios replay a past event, such as the 2008 crisis, the 1998 LTCM and Russia episode or the 2020 market shock. They are easy to explain and credible because they happened. Their weakness is that the next crisis rarely repeats the last one, and they miss new risks and new products.
  • Hypothetical scenarios are built by judgment around a plausible but unseen event, such as a sovereign default, a major cyber outage or a geopolitical shock. They can target the bank's own weak spots. Their weakness is subjectivity: shocks may be inconsistent or set too mild.
  • Macroeconomic scenarios specify paths for variables such as GDP, unemployment, house prices, equity prices and interest rates over several years. Models then translate these into losses, revenue and capital. Supervisory tests such as CCAR, DFAST and EBA exercises work this way.
  • Reverse stress tests start with an outcome, such as capital falling below the minimum or liquidity running out. You then ask which scenarios would cause it. They reveal vulnerabilities that forward scenarios may not.

Two dials apply to every scenario. Severity is how large the shocks are. Plausibility is how believable the event is, including whether the shocks are internally consistent. Good practice is severe but plausible: tough enough to hurt, coherent enough to be taken seriously. Because severity and plausibility pull against each other, scenarios are usually run at several levels, such as baseline, adverse and severely adverse.

A good scenario also covers all relevant risk factors, spans the right horizon, includes second-round effects such as liquidity drying up and correlations rising, and is approved by senior management. Scenarios should be tied to the bank's portfolio, not generic.

Key formulas to remember

Severity vs plausibility
Good scenario = severe but plausible
Severity rising lowers plausibility. Design for the most severe event you can still defend as coherent.
Scenario types
Historical | Hypothetical | Macroeconomic | Reverse
Forward: scenario to loss. Reverse: loss (failure point) to scenario.
Capital impact of a scenario
Post-stress capital ratio = (Capital − stress losses + stress revenue) ÷ Stressed RWA
Compare with the regulatory minimum plus buffers. Stressed RWA can rise as ratings migrate.
Reverse stress test target
Find scenarios where Capital ratio ≤ minimum (or liquidity survival horizon ≈ 0)
The failure point is fixed first. The scenario is the output.

How to solve Stress Testing Scenario Design and Selection questions

Use this order for any scenario design or selection question.

  1. 1Identify the purpose: risk identification, capital planning, limit setting, or supervisory reporting.
  2. 2List the bank's key exposures and vulnerabilities: portfolios, concentrations, funding, business model.
  3. 3Choose the scenario type that fits: historical for credibility, hypothetical for new or specific risks, macroeconomic for capital planning, reverse for finding failure points.
  4. 4Set severity and horizon, and run several levels where useful.
  5. 5Check plausibility and consistency: do shocks agree with each other and with correlations in stress?
  6. 6Include second-round effects such as liquidity, contagion and management actions, stated clearly.
  7. 7Translate shocks into losses, revenue and capital, and compare with limits and risk appetite.
  8. 8Document, challenge and report to senior management, with actions linked to results.

Quickest way: Match the clue to the scenario type

When to use it: For multiple-choice questions asking which approach fits a situation.

  1. Past event named or replayed: historical.
  2. New or bank-specific risk, no precedent: hypothetical.
  3. Paths for GDP, unemployment, house prices over years: macroeconomic.
  4. Starts from failure or breaching capital or liquidity limit: reverse.
  5. Question about too mild or too extreme: severity versus plausibility.
  6. Eliminate options that claim one type is always best.

Common mistakes in Stress Testing Scenario Design and Selection

  • Saying historical scenarios are the most forward-looking

    They feel realistic because they happened.

    Fix: Remember they are backward-looking and can miss new risks. Their strength is credibility, not foresight.

  • Treating reverse stress testing as a forward scenario with a bigger shock

    Both use the word stress.

    Fix: Reverse starts from a defined failure outcome and searches backward for causes.

  • Assuming the most severe scenario is the best

    Bigger losses seem more prudent.

    Fix: Implausible scenarios are ignored by management. Aim for severe but plausible.

  • Applying shocks to each risk factor independently

    It is simpler to set each shock alone.

    Fix: Keep shocks internally consistent and allow correlations to rise in stress.

  • Using the same generic scenario for every bank

    Supervisory scenarios are common to all banks.

    Fix: Add bank-specific scenarios tied to its own concentrations and funding.

  • Ignoring second-round effects

    Models often capture only first-order losses.

    Fix: State liquidity squeezes, collateral calls and feedback effects, and mention them in answers.

Worked examples

Example 1

A bank's board wants to know which events could push its CET1 ratio below the regulatory minimum, without assuming a particular crisis. Which approach fits best?
A. Replay the 2008 crisis
B. Reverse stress test
C. Baseline macroeconomic forecast
D. VaR at 99%

Show the solution
  1. The board fixes an outcome first: CET1 below the minimum.
  2. The task is to find events that cause it, which is working backward from failure.
  3. That is the definition of a reverse stress test.
  4. A replays a known event and does not search for causes. C is not a stress. D measures normal-market loss at a confidence level.

Answer: B. Reverse stress test.

Example 2

A bank has a stress scenario with a 40% fall in equity prices, but credit spreads unchanged and equity volatility falling. A reviewer objects. What is the main design issue and the fix?

Show the solution
  1. A large equity fall normally comes with higher volatility and wider credit spreads.
  2. The shocks are therefore internally inconsistent, which lowers plausibility.
  3. The scenario may understate losses, because credit and volatility exposures are not stressed as they would be in practice.
  4. Fix: redesign the shocks together, using a macro narrative or historical co-movements, so correlations and risk factors move coherently.

Answer: Shocks are internally inconsistent (plausibility issue). Rebuild them jointly with wider spreads and higher volatility alongside the equity fall.

Exam tips

  • Read the first clue in the question: past event, new risk, multi-year macro path, or failure outcome. It usually names the type.
  • Know one strength and one weakness for each scenario type. Options often swap them.
  • The phrase severe but plausible is the standard answer on severity.
  • Link scenarios to the bank's own portfolio and business model when the question mentions vulnerabilities.
  • Expect case-style questions on whether management actions can be assumed. Treat them cautiously and make them explicit.

Practice questions from Stress Testing Banks

Stress Testing Scenario Design and Selection in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Stress Testing Scenario Design and Selection: frequently asked questions

What is the difference between historical and hypothetical scenarios?

Historical scenarios replay a past event, so they are credible and easy to explain. Hypothetical scenarios are built from judgment about events that have not happened. They can target new or bank-specific risks but are more subjective.

What is reverse stress testing in banks?

It starts from a defined failure, such as capital falling below the minimum or liquidity running out, and identifies the scenarios that could cause it. It helps find hidden vulnerabilities and tests whether business model and risk appetite are sensible.

How do I choose stress scenarios for a bank stress test?

Start with the purpose and the bank's main exposures. Then pick the types that fit, set severity and horizon, and check plausibility and consistency. Use several severity levels and add bank-specific scenarios to any supervisory ones.

What does severe but plausible mean?

It means the scenario is harsh enough to reveal real weakness but coherent enough to be believed by management and supervisors. Scenarios that are too mild give false comfort, and those that are implausible get ignored.