Reverse stress testing should be the most interesting conversation in a bank. It is the one exercise where the CRO is allowed to ask: “what, specifically, would break us?” — and is obliged, by regulation, to answer in a way the Management Body can read.
- Pandemic, cyber and macro scenarios — generic.
- Bullet-pointed narrative; ordinal severity.
- Depletion numbers traced back to last year's EBA with a sign flip.
- Read by the JST as technically compliant, not analytically useful.
- Three scenarios: idiosyncratic, systemic, combined.
- Quantitatively-specified non-viability conditions.
- MB-endorsed thresholds + named indicator owners.
- Worth 30–60 bps of P2G on a mid-cap G-SIB.
Reverse stress testing is not a risk-management exercise. It is a governance exercise — and its strategic value sits in converting a qualitative concern into a quantitative answer the JST can read. After the 2023 US-regional turmoil (uninsured deposit runs against unhedged AFS), the SSM moved RST from a supporting-role ICAAP exercise to the artefact the JST now reads first.
"Every CRO has been told their reverse stress test needs to be more 'creative.' What the ECB actually wants is more precise — three scenarios, stated in quantitative failure conditions, owned by the Management Body."
— Ezelman CRO briefing, 2025 SREP post-mortem1 · Why reverse stress testing became a Pillar 2 instrument
The transition from compliance exercise to supervisory instrument happened in three moves over seven years — each one widening the analytical bar the JST applies when it reads the RST.
The operational consequence: the JST now expects the reverse stress test to answer three questions, in the ICAAP itself, and with quantitative rigour:
Q2. At what severity & duration do those shocks cross the threshold?
Q3. What are the observable early-warning indicators — and who owns each one?
If the ICAAP does not contain a defensible answer to all three, the reverse stress test is read as non-credible. And once it is read as non-credible, the JST begins to import conservatism into its Pillar 2G recommendation to compensate for what the bank has not demonstrated about its own fragility. This is the mechanical link from RST quality to capital — and it is, in our experience, worth 30 to 60 bps of P2G on a mid-cap G-SIB.
2 · The three scenarios the ECB actually wants
The 2025 revisions of the ECB's supervisory expectations on ICAAP clarified the structure of reverse stress testing that the JST now expects. Three scenarios — no more, and decisively not fewer.
Idiosyncratic scenario
A failure path driven by the bank's own balance sheet, business model, or governance. Examples: a rapid, name-specific deposit run, a single counterparty concentration triggering cascading losses, a compliance event inducing reputational freeze in wholesale funding. The ECB wants to see that the bank has identified its own fragility points, not industry-generic ones.
Systemic scenario
A failure path driven by a macro-financial event that affects many institutions simultaneously. Examples: severe sovereign stress in a domestic market, a prolonged rate-hike cycle combined with asset-price corrections, large-scale geopolitical disruption of a critical trade corridor. This is the closest to a classic stress test, but reverse-formulated — not "what is the capital impact of scenario X?" but "what systemic configuration exhausts capital before management actions can compensate?"
Combined scenario
The failure path that has, historically, actually produced bank failures: an idiosyncratic weakness interacting with a systemic shock. 2023 SVB was a combined scenario — long-duration asset mismatch (idiosyncratic) meeting a rate-hike cycle (systemic) meeting a narrow depositor base (idiosyncratic). Every CRO who tells us the institution's reverse stress test is "robust" without a combined scenario, is telling us the exercise is not what the ECB is reading.
The test for credibility is not whether each scenario is creative. It is whether each scenario produces a quantitatively specified failure point — a combination of capital, liquidity and funding metrics that crosses a defined non-viability threshold, with a duration, and with an identified point of no-return action. Qualitative RST is not a reverse stress test. It is a discussion document.
3 · From compliance artefact to capital defence: the inversion
The structural move we help banks execute in this area is simple to state and demanding to implement: invert the reverse stress test. Most banks run RST as a scenario-to-outcome exercise (scenario defined first, capital outcome computed). The ECB wants the opposite — outcome defined first (non-viability), scenario space computed to reach it.
Common RST practice — "forward from scenario"
Starts with a curated list of hypothetical events. Runs the existing stress-test infrastructure against them. Reports the resulting capital depletion and compares to buffer. Concludes "scenario X produces a Y bps depletion, the bank remains viable."
- Looks quantitative but is anchored on stress-test engine assumptions.
- Does not identify the minimum shock needed to break the institution.
- Cannot support a Management-Body conversation on action triggers.
- The JST reads it as an extension of the stress test, not a reverse one.
Inverted RST — "backward from failure"
Starts with a defined non-viability condition (e.g. CET1 < 6%, LCR < 80% for 10 consecutive days, unsecured funding access lost for 30 days). Searches the scenario space backward for the mildest configuration that reaches that condition. Reports the severity, duration, and indicator signature.
- Identifies the actual fragility frontier of the institution.
- Produces concrete triggers for management action, tied to indicators.
- Provides the Management Body with a quantitative defence narrative.
- The JST reads it as a credible governance instrument — and prices P2G lower.
The inversion requires two things the bank often does not have: a non-viability condition that the Management Body has formally endorsed, and a scenario-search tooling capable of running backward. Both are achievable inside a twelve-month programme. Neither is a box the existing stress-test function can tick from its existing backlog.
4 · The observable signal the JST is scoring
Supervisors do not just read the RST document. They score the surrounding signals. In our mandate work, six signals consistently appear in the JST assessment of a bank's reverse-stress-test programme. We list them in the order the JST considers them.
Six credibility signals · the JST scores each one
- Management-Body endorsement. The non-viability condition is formally endorsed by the MB, in writing, with a date and a named owner for each indicator. Not delegated to Risk Committee; endorsed by the full board.
- Scenario specificity. Each of the three scenarios is described with sufficient quantitative precision that an external party can reproduce the failure path — not "a severe rate shock" but "a 350 bps shock over three quarters with a 60% correlation to credit spreads."
- Indicator system. Each scenario has a set of early-warning indicators, monitored monthly, reported to a named Executive Committee member, with escalation triggers already in place.
- Recovery-plan linkage. The non-viability thresholds in the RST are the same thresholds used in the Recovery Plan. If they diverge, the JST reads the RST as an academic exercise disconnected from the bank's own preparedness.
- Challenger scenario. At least one scenario was proposed by a non-Risk function (Finance, Treasury, Business) and survived the analytical review. If Risk built all three, the exercise is reading as self-challenged.
- Evolution from prior year. The current RST explicitly references what changed versus the prior year, and why. Static RSTs are read as box-ticks. RSTs that evolve with the balance sheet are read as live governance.
A bank whose RST satisfies all six signals is effectively uninvitable to an upward P2G correction. A bank that satisfies three or fewer is, in our sample, where the additional 30–60 bps comes from.
5 · A worked example — the inverted RST in practice
Mid-cap European G-SIB. Corporate-banking franchise, mid-sized private bank, modest trading book. The story below is anonymised; the structure is the one we have run in mandate.
The bank ran pandemic, cyber, and sovereign-stress. Each produced a CET1 depletion inside the combined buffer. Each was labelled "resilient." None contained a combined idiosyncratic-plus-systemic path.
We rebuilt against a quantitatively-specified non-viability condition. Scenario search ran backward from the condition to identify the mildest configurations that reach it.
CET1 below the Pillar 1 + Pillar 2R floor for at least six consecutive months, with access to unsecured wholesale funding closed at the same time.
Three scenarios emerged as genuinely plausible paths to failure — each with quantitatively-specified severity, duration and trigger structure.
22% AUM loss over six months — combined with a market-wide repricing of fee-income multiples.
+400 bps spread blowout in two of the top-three exposure sovereigns — plus IRRBB impact via AFS losses + private-bank deposit outflow.
Top-20 corporate concentration (within appetite) + 300 bps rate shock over two quarters compresses trading-book hedge effectiveness. 40% concentration default under severe adverse.
The combined scenario was the one the bank had not previously identified — and the rebuild moved from a quant document to a governance instrument.
P2G did not fall to zero, but it fell materially against the internal baseline — one of the clearest single-input contributions we have observed in our mandate history. Mandate-specific figures withheld under sitewide public-data policy.
6 · Why this is a CRO instrument, not a Risk-Modelling one
The last and most important point: reverse stress testing reports to the CRO, not to the Head of Stress Testing. It is not a quant exercise. It is a narrative exercise, quantitatively supported, whose author is the CRO and whose audience is the Management Body.
Where this goes wrong is when the CRO delegates the RST to the stress-testing team. The stress-testing team will produce a technically correct document that answers the question nobody asked. The document the JST wants to read has four authors: the CRO (business-model fragility narrative), the CFO (capital and liquidity thresholds), the Treasurer (funding-access scenarios), and the Chair of the Risk Committee (challenge and endorsement). The Risk-Modelling team supports all four; it does not own any of them.
This is why the first recommendation we make on every reverse-stress-test rebuild is organisational: move the exercise from the stress-testing function to the CRO's own office, with monthly visibility to the Risk Committee, and with a named board-level endorser of the non-viability condition. The quantitative work comes second. The governance work comes first — and is the part the JST can actually see.
7 · Closing — the conversation the ECB is trying to have
A CRO trying to reduce a Pillar 2G number has limited levers. Most of them are not under the institution's control once the SREP cycle is underway. Reverse stress testing is the exception — and the one the ECB has most visibly re-weighted as a credibility signal over the last three years.
Already what it is by the time the SREP letter arrives. Methodology bites in T-1.
Constrained by the existing governance architecture. Cannot be reframed mid-cycle.
Closed on a schedule the bank does not control. Owned by the JST, not by the CRO.
The only lever genuinely inside the CRO's own office — and the one the ECB has re-weighted most visibly.
Not the most technical, novel or interesting — the one the supervisor is most ready to read.
A credible answer can be produced inside a twelve-month window — ahead of the next SREP cycle.
Measurably moves the P2G number that every other Pillar 2 lever cannot — because they are already locked.
Emerge from the cycle with lower P2G — because the JST reads the RST first, and reads it as a governance instrument.
Discover, eighteen months from today, that the conversation has moved without them — and the import-conservatism mechanism is already in their P2G.