Circular CSSF 26/911

What Changed

• - Circular CSSF 26/911 replaces Circular CSSF 25/877 and integrates ESMA’s 2025 Guidelines on stress test scenarios under Article 28 of Regulation (EU) 2017/1131 (MMFR), making the updated scenarios directly applicable in the Luxembourg framework.
• The 2025 ESMA Guidelines (Ref. ESMA50-481369926-30585) update the common reference stress test parameters for MMFs, reflecting more recent market conditions and liquidity risk drivers than the 2024 Guidelines (Ref. ESMA50-43599798-10651).
• The circular clarifies that MMFs and MMF managers must use the updated 2025 ESMA stress test scenarios when preparing the MMF reporting required under the MMFR and the related Commission Implementing Regulation on MMF reporting templates.
• Circular CSSF 26/911 confirms that the 2025 Guidelines and their translations, published by ESMA on 26 March 2026, are now integrated into CSSF supervisory practice, following the ESMA process whereby guidelines apply two months after publication of
• The circular reiterates that MMFs and their managers must tailor the ESMA reference scenarios to the specificities of each MMF, adding additional risk factors or requirements where needed to ensure that stress tests are relevant, robust, and proporti
• The circular confirms that entities must apply the new 2025 Guidelines for the preparation of the MMF reporting with reporting date 30 June 2026 and onwards, meaning that models, methodologies, and internal procedures that were previously aligned to

Suggested Considerations

• Identify all MMFs and MMF mandates in scope of Regulation (EU) 2017/1131 for which the CSSF is the competent authority and confirm that they are currently using the 2024 ESMA stress test framework under Circular CSSF 25/877.
• Obtain and review in detail the ESMA 2025 Guidelines on stress test scenarios (ESMA50-481369926-30585) and the annexed parameters as integrated by Circular CSSF 26/911, comparing them line‑by‑line to the 2024 version to map all methodological and parameter changes.
• Update the MMF stress testing policy and procedures to reference Circular CSSF 26/911 and the 2025 ESMA Guidelines, including explicit descriptions of the scenarios, calibration choices, modelling techniques, and governance for scenario approval.
• Recalibrate stress testing models and tools used for MMFs to reflect the 2025 common reference parameters, ensuring that interest rate shocks, credit spread moves, liquidity shocks, redemption scenarios, and concentration risks are aligned with the new ESMA specifications.
• Perform impact analyses on representative MMFs using both 2024 and 2025 parameters to quantify changes in stress outcomes, and prepare internal briefing materials for senior management and boards explaining the impacts on liquidity and risk profiles.
• Tailor the ESMA reference scenarios to each MMF’s specific risk profile by adding or adjusting risk factors where appropriate, documenting the rationale for any tailoring and ensuring that such tailoring is consistent with the expectations expressed in Circular CSSF 26/911.

Key Dates

Who is Affected