As part of our ongoing series on the ECB’s 2026 Geopolitical Reverse Stress Test, we previously explored why channels matter more than numbers and how geopolitical risk shapes failure pathways in reverse stress testing.

Why This Matters

A key objective of the ECB’s 2026 Reverse Stress Test is for banks to assess the resilience of their business model. This requires a comprehensive taxonomy of geopolitical risk drivers linked to business impact via plausible transmission channels. Without this foundation, reverse stress testing becomes guesswork, blind to hidden vulnerabilities and hard to defend under supervisory scrutiny.

Step 1: Identify and Engage the Right Stakeholders

Creating a useful taxonomy is not a siloed exercise. It requires bringing together a cross-functional working group: risk management to define categories and metrics, treasury and finance to assess balance sheet sensitivities, business lines to validate exposures, geography and concentrations, compliance and legal to capture sanction regimes and regulatory constraints. Early engagement ensures the taxonomy reflects the bank’s unique business model and risk profile.

Step 2: Structure the Taxonomy Using a Layered Approach

The starting point is to move from broad geopolitical themes to tangible impacts. Begin by identifying high-level drivers such as sanctions, trade fragmentation, energy disruption or military escalation.

From there, think about how these drivers ripple through the organization—through financial markets, the real economy, and safety & security. The goal is to connect these channels to your business model and balance sheet exposures, and then drill down to measurable risk parameters like PD/LGD shocks or market sensitivities.

Step 3: Apply Robust Modeling Approaches and “Reverse-Orientation”

Once the taxonomy is defined, the next step is to make it actionable. Start with scenario-based analysis to explore plausible geopolitical shocks and their effects across channels. Then, use sensitivity screening to identify which sectors and counterparties are most exposed.

It is not uncommon for this exercise to yield a constellation of viable assumptions leading to the desired outcome; quantitative methods, such as Monte Carlo simulations or optimization methods, can aid in exploring the solution space and guide in the choice of the scenario which best fits the profile and narrative of your organization. The aim is not to build the most complex model but to ensure the taxonomy translates into meaningful insights for decision-making.

Step 4: Leverage External Data and Benchmarks

No taxonomy should be built in isolation. External data adds credibility and depth. Regulatory guidance from the ECB provides a clear baseline, while industry benchmarks and rating agency data can help calibrate sector sensitivities.

Geopolitical risk indices and historical stress events offer valuable context for scenario design. Combining internal insights with external references ensures your taxonomy reflects both supervisory expectations and real-world dynamics.

Step 5: Establish Governance and Documentation

Finally, governance is what turns a taxonomy into a trusted framework. This means securing board-level oversight, involving cross-functional committees, and maintaining clear documentation of assumptions and methodologies.

Regular updates are essential, as geopolitical risks evolve. A well-governed process not only satisfies regulatory scrutiny but also embeds the taxonomy into the bank’s risk culture, making it a living tool rather than a one-off exercise.

How Zanders Can Help

We guide banks through this process end-to-end:

• Quantitative modeling to support or benchmark scenario design.
• Advisory support to design and validate a complete taxonomy.
• Hands-on assistance during stress test exercises, leveraging experience with European banks.
• Tooling development or deployment of our Credit Risk Suite (CRS) for scenario modeling, automated ECL/CET1 impact calculations, and advanced optimization techniques.

Transform compliance into strategic capability for resilience. Contact us to find out how we can help your organization.

Read our previous blog on ECB 2026 Geopolitical Reverse Stress Test.

Why This Matters

For banks, the ECB’s 2026 thematic reverse stress test on geopolitical risk is more than a regulatory exercise. It’s a reality check on failure pathways. The cost of missing how shocks transmit through your business can be severe: capital depletion, liquidity strain, and reputational damage when the next crisis hits.

This is not about ticking boxes or plugging in generic macro scenarios. It is about demonstrating to supervisors and to your board that you understand which channels could break your business model and how those channels map to tangible impacts on capital, liquidity, and operations.

In reverse stress testing, you start from a pre-defined failure outcome and work backwards to plausible scenarios that could cause it. In our previous blog, we argued for a bank-specific taxonomy of geopolitical risk drivers because reverse stress testing is only credible when the transmission channels are correctly selected and explained. Today, we take the next step: translating a risk driver into business‑model impact that can credibly produce the failure condition.

Worked Example: Military Escalation

In the context of Military Escalation, as an illustrative example, let’s consider a conflict disrupting shipping lanes in the South China Sea. The chain of transmission may unfold as follows:

• The incident would disrupt global trade routes, creating severe supply chain¹ bottlenecks and driving up costs for  industries depending on imports from and exports to the region. These disruptions would ripple through the real economy, affecting manufacturing, logistics, energy and semiconductor² sectors, and ultimately impacting banks with concentrated exposures in these sectors.

• Investors would seek safe assets, triggering sharp movements in commodity and foreign exchange markets. Banks with open positions in these markets could face significant mark-to-market losses, while liquidity strains emerge as funding costs rise. In addition, cargo insurance premiums on conflict‑adjacent corridors can spike, prompting re-routing and a broader repricing of risk.

• Operational risks would likely increase. Military tensions often coincide with heightened cyber and/or physical threats, increasing the likelihood of state-sponsored attacks on financial infrastructure. Banks would need to increase investment in cyber defence and resilience measures.

• Sanctions may be imposed by multiple parties, exposing banks to potential breaches and contractual disputes with counterparties linked to conflict zones. This adds complexity to transaction screening and legal oversight.

• Finally, these channels translate into measurable risk parameters. Credit portfolios tied to vulnerable sectors would see severe PD shocks, alongside LGD adjustments for collateral impacted by trade restrictions. Together with the market and operational risk impacts described above, they could erode CET1 ratios, revealing failure pathways that standard stress tests might miss.

Reverse The Logic

Because a reverse stress test starts from the outcome, the final step is iterative - the engine room of the exercise. To reach the targeted impact (300 bps CET1 depletion in the ECB’s thematic exercise), you will likely cycle through the channel, mechanism, risk‑parameter mapping and tune the shocks, strengthening or weakening their severity and duration until the constellation of assumptions consistently delivers the failure condition. But a key fallacy is to treat this as a mechanic “tuning” exercise rather than a careful consideration of which combination of shocks and channels that plausibly will drive CET1 below the threshold?

Scaling This Approach

The method extends to other relevant drivers: sanctions, energy disruptions, cyber threats, but the taxonomy must be granular and defensible, with a clear line‑of‑sight from event to channel, and then to portfolio, risk parameters and capital metrics. This strengthens Reverse Stress Testing credibility and ICAAP alignment, and produces governance‑ready narratives for senior decision‑makers.

How We Can Help

We support banks in building a robust RST framework. Our approach includes:

• Advisory support to design a purposeful, bank-specific taxonomy and link it to ICAAP.
• Quantitative modeling to support or benchmark scenario design.
• Hands-on assistance during stress test exercises, leveraging our experience with several European banks.
• Tool development and deployment of our Credit Risk Suite (CRS) for scenario modeling, automated ECL and CET1 impact calculations, and advanced scenario building.

With Zanders, you can move beyond compliance to create a stress test framework that enhances your strategic capability.

Introduction: Why This Matters Now 

Geopolitical risk has become a defining feature of today’s financial landscape. Trade fragmentation, sanctions, and regional conflicts are reshaping markets and business models. Recognizing this, the European Central Bank (ECB) will run a thematic Reverse Stress Test (RST) on geopolitical risk in 2026 as part of its explicit supervisory priorities. Unlike traditional stress tests, RST starts from a failure condition and works backward to identify plausible scenarios that could lead to this situation.  

Hence, this exercise is not about plugging in generic macro shocks—it’s about uncovering hidden vulnerabilities. And that requires one critical ingredient: an informed and detailed view of how geopolitical events may affect your organization. 

The Key Challenge: Seeing the Full Picture 

To pass muster with supervisors, selecting and explaining the transmission channels will matter far more than the numerical modeling. If relevant channels are missed, the backward search becomes blind, undermining the credibility of the entire exercise. The ECB has made clear that banks must go beyond traditional macroeconomic modeling and identify how disruption to trade flows and supply chains, cyberattacks, and even physical risks related to conflicts might affect banks and their clients, and in turn how this transmits to banks’ capital, liquidity, and operations.  

While the ECB has mapped out the primary pathways through which geopolitical risks propagate, the size and nature of the impact will very much depend on each bank’s location, exposures, and business models — meaning a one-size-fits-all approach will not work. Reverse stress testing is designed to uncover failure pathways, but this only happens if transmission channels have been studied and selected with care.  

Building a granular, bank-specific taxonomy of geopolitical risk drivers and their linkages to the portfolio is therefore a critical step. 

What Does a Geopolitical Risk Taxonomy Look Like? 

Well-defined transmission channels should link high-level risk drivers to specific impacts and risk parameters. For example: 

• Drivers: Trade tensions, sanctions, regional conflicts, cyber threats, energy disruptions, and overall market volatility. 

• Impacts: Credit losses (through direct and indirect exposures), loss of revenue (loss of markets, loss of pricing power), cost increases (funding costs, safety and security measures, insurance premiums, staff compensation and relocation), compliance and legal risks (sanctions breaches, disputes). 

• Risk Parameters: PD and LGD shocks, market risk factors, operational risk metrics. 

Once relevant transmission channels have been defined and quantified, the severity of the shocks to the risk drivers can be tuned so that the targeted reverse stress impact is achieved. In the case of the ECB reverse stress test, a CET1 capital impact of 300 basis points is targeted. Finding a balanced set of shocks to achieve the reverse stress target will require expert judgement and needs to be documented properly. 

A layered approach like this will help ensure that the exercise does not become a paper product but a strategic diagnostic tool that meets supervisors’ expectations. In our next blog, we will spend more time on how to set up a proper taxonomy and make it actionable for your organization. 

How Zanders Can Help 

At Zanders, we support banks in building a robust RST framework. Our approach includes: 

• Quantitative modeling to support or benchmark scenario design.  

• Advisory support to design a purposeful, bank-specific taxonomy and link it to ICAAP. 

• Hands-on assistance during stress test exercises, leveraging our experience with several European banks. 

• Tool development and deployment of our Credit Risk Suite (CRS) for scenario modeling, automated ECL and CET1 impact calculations, and advanced scenario building. 

With Zanders, you can move beyond compliance to create a stress test framework that enhances your strategic capability.