T2S Release R2026.SEP – 21 September 2026 – Update II

Note: This Announcement, originally published on 13 March 2026 and updated on 29 June 2026, has been further updated to confirm the software implementation in the T2S client testing environment UTEST. Changes have been highlighted.

Clearstream Europe AG¹ informs clients about the TARGET2-Securities (T2S) Release R2026.SEP. According to the T2S Release Concept the resolution for T2S Problem Tickets (PBIs) will be deployed during the maintenance window on the weekend

19/20 September 2026
for the business day Monday, 21 September 2026

T2S Release R2026.SEP - Scope

Based on the T2S status reporting of beginning of August 2026, twelve Problem Ticket (PBIs) have been assigned to be resolved with T2S Release R2026.SEP. Four of them can affect CEU Directly Connected Participants (DCPs), one of these cash DCPs. CEU recommends that DCPs check the PBI list attached.

CEU’s assessment related to these Problem Tickets shows that the fixes will not require any changes in CEU’s software.

T2S Release R2026.SEP – Transition plan

The Market Infrastructure Board (MIB) will decide on the deployment of T2S Release R2026.SEP to production based on the outcome of the testing campaign.

The implementation of the software will take place during the weekend’s T2S maintenance window – meaning that currently no changes to the T2S Operational Day are expected for the End of Day (EOD) procedure on Friday, 18 September 2026, or for the start of business day, Monday, 21 September 2026.

The table below provides an overview of the important T2S milestones within the next months:

T2S Release R2026.SEP – implementation timeline

Client simulation

The updated software for T2S Release R2026.SEP has been installed on Thursday, 13 August 2026, in the T2S Pre-Production Environment (UTEST). CEU clients can test in a free simulation mode from 17 August to 1 September 2026.

DCPs can test in the T2S client simulation environment (UTEST).

ICPs can test in the CEU client simulation environment (IMS23). The already established static data for CEU accounts and the related connectivity settings in the CEU client simulation environment (IMS23) remain unchanged. If clients need any adjustments of the setup in the client simulation environment or additional information on the simulation requirements, they can contact connect-test@clearstream.com.

For details about the availability of the client simulation environment UTEST,  please refer to Availability and schedules of the client simulation.

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1. This announcement is published by Clearstream Europe AG (CEU), registered office at Mergenthalerallee 61, 65760 Eschborn, Germany, registered with the Commercial Register of the District Court in Frankfurt am Main, Germany, under number HRB 7500.