MiFIR Transaction Reporting and Best Execution Data Requirements
MiFIR reporting obligations generate millions of daily transaction records that must be accurate, complete, and submitted to ARMs within T+1 — leaving no tolerance for data quality failures.
MiFIR (Markets in Financial Instruments Regulation, EU 600/2014) imposes transaction reporting obligations on investment firms for trades in financial instruments admitted to trading on EU venues, or where the underlying is such an instrument. Under Article 26, firms must report to a competent authority via an Approved Reporting Mechanism (ARM) by close of business on T+1. Reports must contain up to 65 data fields defined in RTS 22 (Commission Delegated Regulation 2017/590), including LEI of the executing and transmitting firm, client identification (using LEI, NCA ID, passport number, or date of birth concatenation per RTS 22 Annex II), instrument identification (ISIN or AII), price, quantity, trading venue, and transaction reference numbers. The UK retained MiFIR post-Brexit as UK MiFIR, with FCA supervisory oversight replacing ESMA.
The engineering challenge in MiFIR reporting centers on data enrichment and lineage. A single trade event in an OMS or EMS must be enriched with counterparty LEIs (validated against the GLEIF register), instrument ISINs (sourced from FIRDS, ESMA's Financial Instruments Reference Data System), venue MICs, and execution decision maker identifiers before submission. The ARM submission format follows ISO 20022 or the ARM's proprietary XML schema. Reconciliation between the firm's internal trade store and ARM acknowledgement files (accepted, rejected, or warning statuses) must be automated and exceptions escalated within the T+1 window. Best execution reporting under RTS 27 and RTS 28 (now reformed under MiFIR Review) adds quarterly publication obligations requiring aggregation of execution quality statistics by instrument class and execution venue.
Post-Brexit divergence between EU MiFIR and UK MiFIR is an active compliance engineering concern. The EU MiFIR Review (Regulation 2024/791, effective 2026) introduces new data fields, removes the double volume cap mechanism, and reforms the consolidated tape structure. Firms operating in both jurisdictions must maintain parallel reporting pipelines with jurisdiction-specific field mappings and validation rules. A persistent edge case is the treatment of give-up and give-in trades, where the clearing member and executing broker differ — RTS 22 Article 4 prescribes specific reporting party determination logic that must be encoded in the trade flow. Late or erroneous reports carry fines under MAR Article 30 and national competent authority enforcement frameworks.
We build MiFIR reporting pipelines that automate trade capture, LEI and ISIN enrichment via GLEIF and FIRDS APIs, RTS 22 field population, ARM submission, and reconciliation against acknowledgement files. Our systems support dual EU/UK MiFIR reporting with jurisdiction-specific validation and audit trail retention meeting the 5-year record-keeping requirement.
Compliance-Native Architecture Guide
Design principles and a structured checklist for building software that is compliant by default — not compliant by retrofit. Covers data architecture, access controls, audit trails, and vendor due diligence.