Multi-platform stock position reconciliation

Purpose

To validate and align internal position records with external trading platform data by automatically matching positions, detecting mismatches, and generating reconciliation outputs for trading operations and back-office accounting.

This workflow ensures:

• Accurate posting of positions to the general ledger
• Reliable alignment between internal systems and custodians
• Early detection of settlement delays and corporate actions
• Reduction of operational risk due to mismatched holdings
• Continuous improvement of instrument mapping and data quality

Data sources

1. Trading platform reports: External stock or instrument holdings from one or multiple broker/custodian platforms (e.g. Exante, Interactive Brokers, etc.)
2. Internal position records: Internal system’s representation of current positions.
3. Optional: Instrument mapping: Created based on matching results after the initial run.

Key processing steps

1. Symbol and instrument normalization

• Standardizes instrument identifiers across systems:
  • Remove suffixes (e.g., .NYSE, .NASDAQ, .LSE)
  • Normalize currency or contract formatting
  • Apply mapping tables where symbols differ across platforms
• Generates unified symbol keys for matching (regex expressions to remove symbols, standardize numbers).

2. Position reconciliation

• Performs multi-layered matching using:
  1. Direct mapping table matches: Internal vs. Broker instrument IDs.
  2. Normalized symbol matches: When mapping is missing or incomplete.
  3. Fallback heuristic matching: Based on partial name similarity, ISIN, or underlying asset.
• Calculates quantity differences between Internal vs. Broker.

3. Discrepancy detection

• Flags positions where quantities differ significantly (>1.0 difference)
• Identifies unmatched positions in either system
• Creates updated mapping suggestions for positions that match well

4. Reconciliation output generation

• Builds structured outputs for downstream reporting:
  • Clean reconciled positions (perfect matches)
  • Internal-only positions (unmatched internal)
  • External-only positions (unmatched external)
  • Suggested updated mapping table
• Excludes ambiguous matches that require manual verification.

Outputs

1. Matched positions - Internal and platform quantities match.
2. Unmatched internal records - Holdings present only in internal systems.
3. Unmatched trading platform records - Holdings present only in platform data.
4. Statistics - Summary of matching results
5. Updated instrument mapping file – Suggested mapping improvements for future automations.

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