Complete SEDOL Lookup Guide: UK Securities Identifier

Last updated: February 2026 · 8 min read

SEDOL (Stock Exchange Daily Official List) is the primary securities identifier used in the United Kingdom and Ireland. Assigned by the London Stock Exchange, SEDOLs are essential for anyone trading on UK markets or working with UK-listed securities. This guide explains the structure, validation, lookup methods, and ISIN conversion for SEDOLs.

What Is a SEDOL?

A SEDOL is a 7-character alphanumeric code that uniquely identifies a security. It consists of 6 identification characters plus a check digit. SEDOLs are assigned by the London Stock Exchange Group (LSEG) and are used across UK, Irish, and many international markets.

Unlike CUSIPs (which are licensed), SEDOLs are available through various free and paid data sources. They're embedded in UK ISINs, making conversion straightforward.

SEDOL Structure

SEDOL Check Digit Algorithm

The SEDOL check digit uses a weighted sum with weights 1, 3, 1, 7, 3, 9 applied to the first 6 characters:

1. Convert each character to a number: digits stay as-is, letters use B=11, C=12, D=13, F=15, G=16, H=17, J=19, K=20, L=21, M=22, N=23, P=25, Q=26, R=27, S=28, T=29, V=31, W=32, X=33, Y=34, Z=35
2. Multiply each value by its weight: position 1 × 1, position 2 × 3, position 3 × 1, position 4 × 7, position 5 × 3, position 6 × 9
3. Sum all products
4. Check digit = (10 − (sum mod 10)) mod 10

Worked Example: HSBC Holdings

SEDOL: 0540528

Characters: 0  5  4  0  5  2
Weights:    1  3  1  7  3  9
Products:   0  15 4  0  15 18
Sum: 0 + 15 + 4 + 0 + 15 + 18 = 52
Check digit: (10 - (52 mod 10)) mod 10 = (10 - 2) mod 10 = 8
SEDOL: 0540528 ✓

Major UK Securities: SEDOL Reference

Converting SEDOL to ISIN

UK ISINs embed the SEDOL with padding:

UK ISIN:   GB  00  0540528  6
           ^^  ^^  ^^^^^^^  ^
           |   |   |        |
           |   |   SEDOL    Luhn check digit
           |   Zero padding
           Country code (Great Britain)

To convert SEDOL → ISIN: prepend GB00, append the Luhn check digit. To extract SEDOL from a UK ISIN: take characters 5–11.

Where to Look Up SEDOLs

• London Stock Exchange: londonstockexchange.com — official source, shows SEDOL on every security page
• LSEG SEDOL Masterfile: The definitive commercial database (paid). Over 70 million SEDOLs assigned since inception.
• Bloomberg Terminal: Type {ticker} <Equity> DES — SEDOL shown in description page
• OpenFIGI: Free API that maps between SEDOL, ISIN, and other identifiers
• Hargreaves Lansdown: UK broker — shows SEDOL in security detail pages
• interactive investor: UK broker — SEDOL visible in instrument information

SEDOL vs Other Identifiers

Frequently Asked Questions

Why don't SEDOLs contain vowels?

To prevent accidentally forming offensive words. When the system was expanded to include letters, LSEG deliberately excluded A, E, I, O, and U. This is a common practice in identifier systems (similar reasoning applies to UK vehicle registration plates).

Do Irish securities have SEDOLs?

Yes. Securities listed on Euronext Dublin (formerly the Irish Stock Exchange) are assigned SEDOLs. Irish ISINs start with "IE" and embed the SEDOL the same way UK ISINs do.

Can I use SEDOL to identify US stocks?

No. US stocks use CUSIP as their national identifier. However, if a US stock is cross-listed on the London Stock Exchange (e.g., via a depositary receipt), the LSE listing will have its own SEDOL.