Most modern personal finance tools rely on Open Banking to aggregate account balances, and for standard UK current accounts it works well: it's a regulated, standardised, genuinely useful piece of infrastructure. Applying the same model to investment tracking is a different problem, though, because the regulation and the platforms behind it were built for payment accounts, not brokerage accounts.
Here's a technical look at why that gap exists, and why we built Omnicogi's import around CSV files rather than an Open Banking connection.
1. The Open Banking technical divide: Banks vs Brokers
Under the UK Payment Services Regulations (implementing PSD2) and the CMA Open Banking Order, the UK's nine largest retail banks (the CMA9) were legally mandated to provide standardised read/write APIs for payment accounts (current accounts and credit cards).
Investment platforms, stockbrokers, and wealth managers (e.g., Hargreaves Lansdown, Fidelity, Interactive Investor, Vanguard UK) fall outside that mandate. That's not a failing on their part — brokerage data (equity lots, corporate actions, dividend withholding) is a fundamentally different shape of data to a current-account transaction feed, and no equivalent standard has been built for it yet. In practice this leaves a few structural options for anyone wanting programmatic access to a UK brokerage account:
- No standardised investment endpoints: There is no universal UK Open Banking standard for reporting equity lot allocations, corporate actions (stock splits, rights issues), or dividend tax withholding.
- Screen scraping as a workaround: Some aggregators fall back on reverse-engineered web scrapers. These can work, but they require handing over your primary broker credentials or session tokens to a third party, and they tend to break whenever the broker updates 2FA flows or page layouts.
- Broad-scope tokens: Where an AISP token is available at all, it often requests standing 90-day access to full transaction histories across all linked accounts, rather than a narrower scope limited to what a tracker actually needs.
2. Two ways to get broker data into a tracker
| Dimension | Open Banking / Aggregator API | CSV Import |
|---|---|---|
| Credential handling | Broker/bank OAuth tokens or login credentials are stored with a third party. | Your login never leaves your broker's own website — you export the file yourself. |
| Connection lifecycle | A standing background access token, typically renewed every 90 days. | One-off: you upload a file when you want your data refreshed. |
| Ongoing effort | Set up once, then updates automatically in the background. | You re-export and re-upload periodically — more manual, but nothing runs unattended. |
| Failure modes | Token expiry or a broker layout change can silently break the connection. | A malformed or unexpected CSV column fails visibly at upload time, so you know immediately. |
Both are legitimate approaches, and which matters more — "set and forget" automation, or knowing exactly what has access to your account and when — is a judgment call. For a UK brokerage account specifically, where no mature Open Banking standard exists yet and scraper-based aggregation means handing over credentials, we think CSV import is the better trade-off today. That could change as investment-specific Open Banking standards mature.
3. How CSV ledger processing works in Omnicogi
Omnicogi processes raw, official transaction exports directly from your broker. The data pipeline follows four deterministic stages:
[ Broker CSV Export ]
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1. Format & Delimiter Normalisation (DD/MM/YYYY, ISO-8601, GBP/GBX)
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2. Security Resolution (ISIN, SEDOL, & Ticker Mapping)
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3. Transaction Deduplication (Cryptographic Hashing per Trade)
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4. Ledger Construction (Clean Cash vs Generated Wealth & Section 104 Pools)
- Header & Delimiter Detection: The parser detects broker-specific schemas (e.g., Interactive Investor, Fidelity, HL, Trading 212, AJ Bell, Vanguard) and normalises London Stock Exchange pricing units (pence
GBXvs poundsGBP). - Security Resolution: Descriptions and local ticker symbols are matched to verified financial instruments using international securities identification numbers (ISIN) and SEDOL codes.
- Deduplication: Each transaction is hashed using its trade date, execution price, quantity, and reference number, so re-uploading an overlapping quarterly or annual export doesn't double-count anything.
- Running Cost Basis & Performance: Cash flows are split into Clean Cash (external deposits/withdrawals) and Generated Wealth (reinvested income and capital growth), updating running HMRC Section 104 pools and XIRR return models.
4. How to export CSVs from major UK brokers
Every major UK investment platform provides native CSV transaction export functionality:
- Interactive Investor (ii): Log in → Portfolio → Select Account → History & Transactions → Set date range → Click Download CSV.
- Fidelity International: Log in → Select Account → Account Activity → History → Click Download to spreadsheet (CSV).
- Hargreaves Lansdown: Log in → Select Account → Transactions tab → Click Export to CSV / Excel at the base of the table.
- Trading 212: Web/App → History → Click Export icon → Select Custom Period (up to 365 days per batch) → Download.
- AJ Bell: Log in → Documents & Statements → Transaction History → Export as CSV.
- Vanguard UK: Log in → My Accounts → Transaction History → Select date range → Download CSV.
5. Summary
If you're reviewing performance on a weekly, monthly, or quarterly cadence rather than needing a live-updating balance, a CSV upload trades a bit of manual effort for not having to share broker credentials with a third party at all. For UK brokerage accounts, where a mature Open Banking standard doesn't yet exist, that trade-off is one worth knowing about regardless of which tracker you end up using.
Disclaimer: Omnicogi is an independent financial tracking software application, not an FCA-regulated financial adviser, tax consultancy, or banking service. Transaction parsing and performance calculations are provided for personal record-keeping and educational purposes. Always verify ledger outputs against your official broker valuation statements.