ISDA has published the ISDA SIMM™ Methodology, version 2.5A, with an effective date of July 15, 2023.
This version of SIMM includes updates based on the off-cycle recalibration of only the main interest rate delta risk weights and testing of the methodology as part of industry quarterly monitoring exercise. The SIMM methodology remains a central part of the SIMM Governance Framework that SIMM users are expected to adhere to.
The effective date of July 15, 2023 means that SIMM users should use SIMM version 2.5A to calculate the initial margin for Close of Business (COB) on Friday, July 14, 2023 onwards. This means that the first day for exchange of initial margin calculated using SIMM version 2.5A would be on Monday, July 17, 2023.