SEDOL validator
How the SEDOL format works
- Format
- 7-character alphanumeric security identifier (6-character base + 1 check digit)
- Example
- 0263494
Things to watch for
- A valid checksum only confirms the code is well-formed — it doesn't confirm the security is actually listed on the London Stock Exchange; check the LSE's own reference data for that
- Vowels (A, E, I, O, U) never appear in the 6-character base — only digits and consonants — so a code containing one is invalid regardless of the check digit
- For a UK security, its ISIN is often just 'GB00' + the 7-character SEDOL + one more ISIN check digit
^[0-9BCDFGHJKLMNPQRSTVWXYZ]{6}[0-9]$A SEDOL (Stock Exchange Daily Official List) code is the 7-character identifier the London Stock Exchange assigns to securities trading on, or historically listed on, UK and Irish markets — shares, bonds, funds, and other instruments. Custodians and back-office systems in the UK have used it for decades to key trades and settlement instructions to one specific instrument, independent of whichever ticker happens to be quoted on screen.
Of the 7 characters, the first 6 form the base code and the 7th is a check digit. The base is deliberately built only from digits and consonants — the vowels A, E, I, O, and U never appear in it, by design.
How this validator works
This tool first rejects any code whose 6-character base contains a vowel, since that alone makes a SEDOL invalid regardless of the check digit. It then recomputes the 7th character using a weighted mod-10 formula: each of the 6 base characters converts to a numeric value (0-9 for digits, 10-35 for A-Z), gets multiplied by a fixed per-position weight — 1, 3, 1, 7, 3, 9 — and the results are summed and reduced mod 10. A mismatch against the actual 7th character fails the check. Everything runs client-side in your browser — nothing you type is sent anywhere.
What a pass doesn’t tell you
A pass confirms the code is well-formed and internally consistent — not that the security is currently listed on the London Stock Exchange, or that it was ever actually issued. A SEDOL assigned years ago to a security that’s since delisted or merged still clears this checksum, since format and check-digit math can’t detect that on their own. To confirm a security is real and currently listed, check the London Stock Exchange’s own reference data.
Content last reviewed 2026-07-23.
SEDOL FAQ
Why do SEDOL codes never contain vowels?
The base code is deliberately restricted to digits and consonants, excluding A, E, I, O, and U. That single rule means any code with a vowel in its first 6 characters is invalid on sight, before the check digit even enters into it.
How is a SEDOL different from a CUSIP or an ISIN?
A SEDOL is the London Stock Exchange's own 7-character scheme, mainly for UK and Irish securities, while a CUSIP is the equivalent 9-character scheme for US and Canadian securities — different length, different issuing body, different check-digit formula. An ISIN is the global wrapper both feed into: a UK security's ISIN is often just 'GB00' plus its SEDOL plus one further ISIN check digit.
Does a valid SEDOL mean the security is currently tradable?
No. A passing result only confirms the code is correctly formatted and its check digit is mathematically consistent — it doesn't confirm the security is listed, still trading, or belongs to the company you expect. For a live status check, use the London Stock Exchange's own reference data or a broker.