SEDOL Validator

SEDOL: the London Stock Exchange's 7-character security code

A SEDOL (Stock Exchange Daily Official List) is the 7-character security identifier assigned by the London Stock Exchange. It uniquely tags equities, bonds and other instruments traded on UK markets and feeds directly into the international ISIN. This tool checks that a SEDOL is well-formed and that its 7th-character check digit is correct.

Since 2004, SEDOLs are alphanumeric: the first six characters can be digits or consonants, but the vowels A, E, I, O and U are never used — this avoids accidental words and reduces transcription confusion. The seventh character is a computed check digit (always 0–9).

How the check digit is computed for B0YBKJ7

• 1. Character values: digits are themselves (0–9); letters take ASCII − 55, so B=11, C=12, … Z=35.
• 2. Weights: multiply the six leading characters by 1, 3, 1, 7, 3, 9.
• 3. Sum: add the six weighted values together.
• 4. Check digit: (10 − (sum mod 10)) mod 10 — the same closing step as the GS1 mod-10 family.

Where SEDOL fits

• Into the ISIN: a UK ISIN is GB + the SEDOL left-padded to 9 characters + an ISIN check digit.
• Settlement & custody: clearing systems and custodians key trades off the SEDOL.
• Market data: a stable, market-level handle distinct from the company-level ticker.

Common pitfalls

• Using vowels: A, E, I, O, U never appear in a valid SEDOL — a vowel means the code is malformed.
• Wrong letter values: it is ASCII − 55 (B=11), not A=1; getting the offset wrong breaks every checksum.
• Weight order: the weights 1,3,1,7,3,9 are positional and must align left-to-right with the first six characters.
• Pre-2004 numeric SEDOLs: old codes were purely numeric and could differ in form; modern ones are alphanumeric and often start with B.
• Valid check ≠ active security: a correct check digit doesn't mean the SEDOL is currently allocated or trading.

FAQ

Why are vowels excluded? To stop SEDOLs forming real words and to cut down on read/keying errors between similar-looking characters.

Can the check digit be a letter? No — the 7th character is always a digit 0–9, computed by the weighted mod-10 formula.

Is a SEDOL the same as a ticker? No. A ticker is an exchange's short trading symbol; a SEDOL is a stable identifier that also rolls up into the ISIN.