In the Update on Enhancing Liquidity (PDF), the LME announced its intention to introduce Self-Match Prevention (“SMP”) also known as Self-Execution Prevention (SEP) on LMEselect. This will be available from 9 November 2026.
What is Self-Match Prevention?
SMP is designed to prevent orders originating from the same participant and subject to the same execution decision-maker from executing against one another. The optional functionality provides members and market participants with an additional tool to help manage trading activity and support compliance with applicable market conduct requirements.
The introduction of SMP forms part of the LME's broader commitment to maintaining fair, orderly and efficient markets, while providing participants with functionality commonly available across global electronic trading venues.
Implementation
SMP will be available on LMEselect from 9 November 2026.
The SMP functionality will be available for participants to begin testing from Monday 28 September 2026.
What is an SMP ID?
An SMP ID is an identifier applied to an order which enables SMP to work.
When two orders carrying the same SMP ID would otherwise trade against one another, LMEselect applies the SMP logic and prevents the execution from occurring.
An SMP ID can be registered and pre-configured on LMEoptic before the order is submitted. For more details, please see the LMEoptic User Guide (PDF).
SMP configurations
Members can configure the SMP Action in 3 ways:
- Cancel Incoming – this will cancel the incoming order
- Cancel Resting – this will cancel the resting order
- Cancel both – this will cancel both the resting and incoming orders with the matching SMP ID
Illustrative scenario: a member enters an order with SEP ID 1234, while there is an existing bid resting in the orderbook with a matching SEP ID 1234.
