SEDOL Validator
ValidatorValidate SEDOL (Stock Exchange Daily Official List) securities codes. Checks the 7-character format and recomputes the official check digit. Runs entirely in your browser.
About this tool
About SEDOL Validator
A SEDOL (Stock Exchange Daily Official List) is a 7-character identification code assigned to securities traded on the London Stock Exchange and other UK/Irish markets. It's made up of a 6-character alphanumeric body — which never contains the vowels A, E, I, O, or U, to avoid resembling real words — followed by a single check digit. SEDOLs are also embedded directly inside the UK's national securities identifying number (NSIN) portion of GB-prefixed ISINs.
The validator strips whitespace, verifies the 7-character format (6 alphanumeric characters excluding vowels, followed by 1 digit), maps each of the first 6 characters to its numeric value (digits as themselves, letters A=10..Z=35), multiplies each by its positional weight (1, 3, 1, 7, 3, 9), sums the results, and compares the computed check digit against the 7th character.
Use this to verify a SEDOL pasted from a UK brokerage statement, fund factsheet, or market-data feed before using it in a trade, to debug why a SEDOL is being rejected by a validation layer, or to sanity-check a SEDOL extracted from the NSIN portion of a GB-prefixed ISIN.
Instant, fully client-side validation with no data ever leaving your browser. Note this checks structural validity only — it does not confirm the SEDOL is actually registered to a real security, which requires access to the London Stock Exchange's SEDOL Masterfile.
Key Features
- Full 7-character format validation
- Rejects vowels in the 6-character body, matching the official SEDOL alphabet
- Recomputes and compares the official check digit
- Clear error messages for each failure mode
- Verified against real published SEDOLs
- 100% browser-based, no data ever transmitted
FAQ
SEDOL Validator — Frequently Asked Questions
What is a SEDOL number?
SEDOL stands for Stock Exchange Daily Official List. It's a 7-character alphanumeric code used to uniquely identify securities listed on the London Stock Exchange and other UK and Irish markets, maintained by the London Stock Exchange Group.
How is the SEDOL check digit calculated?
Take the first 6 characters, map each to a numeric value (digits are themselves, A=10 through Z=35), multiply each by its position weight — 1, 3, 1, 7, 3, 9 in order — sum the results, and subtract the total from the next multiple of 10.
Why can't a SEDOL contain the letters A, E, I, O, or U?
Vowels are deliberately excluded from the SEDOL alphabet so that generated codes never accidentally spell offensive or confusing words. This is a common design choice in other security identifiers too, though the exact excluded set varies.
What's the difference between a SEDOL and an ISIN?
A SEDOL identifies securities specifically within the London Stock Exchange system, while an ISIN is a global standard. For most UK securities, the ISIN is 'GB00' + the 6-character SEDOL body + a separate ISIN check digit — the SEDOL is embedded directly inside the ISIN's NSIN field.
Why does my SEDOL fail validation?
The most common cause is a single mistyped or transposed character. Also confirm the code is exactly 7 characters with no spaces or dashes, and that it doesn't contain a vowel — a vowel anywhere in the first 6 characters means it was never a valid SEDOL to begin with.
Tips
- Strip spaces and dashes before validating — some data feeds format SEDOLs with separators that aren't part of the official code
- If the check digit fails, try re-copying the SEDOL from its original source — the most common error is a single transposed character
- For UK securities, the SEDOL is embedded directly in the ISIN — check the ISIN Validator tool if you have a full 12-character ISIN instead
- This validator never sends your SEDOL anywhere — the check digit is recomputed entirely in your browser
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