@credentum/is-valid-sedol

Validate SEDOL (Stock Exchange Daily Official List) codes used in UK and Irish securities markets.

Installation

npm install @credentum/is-valid-sedol

Usage

import { isValidSedol } from '@credentum/is-valid-sedol';

isValidSedol('0263494'); // true  (BAE Systems)
isValidSedol('B0WNLY7'); // true  (Tesla on LSE)
isValidSedol('INVALID'); // false

Why Use This?

SEDOL is the primary security identifier for the London Stock Exchange. If you process UK/Irish equities, bonds, or ETFs, you encounter SEDOLs in SWIFT messages, FIX protocol feeds, and reconciliation files. The check digit algorithm is simple but easy to get wrong — and a bad SEDOL silently corrupts downstream data. This package gives you a single, zero-dependency function with correct weighted-checksum validation so you don't have to copy-paste from Wikipedia.

API

isValidSedol(input: string): boolean

Returns true if the input is a valid 7-character SEDOL with a correct check digit.

Validation rules:

• Exactly 7 characters
• Characters 1-6: digits 0-9 or consonants BCDFGHJKLMNPQRSTVWXYZ (no vowels)
• Character 7: check digit (weighted mod-10 checksum with weights [1, 3, 1, 7, 3, 9, 1])

Parameters: | Name | Type | Description | |------|------|-------------| | input | string | The SEDOL code to validate |

Returns: boolean — true if valid, false otherwise.

Edge cases:

• Non-string input returns false
• Empty string returns false
• Lowercase input returns false (SEDOLs are uppercase)
• Strings with vowels return false

Algorithm

Each character maps to a numeric value (digits = face value, B=11, C=12, ..., Z=35). The values are multiplied by weights [1, 3, 1, 7, 3, 9, 1] and summed. A valid SEDOL has a total divisible by 10.

License

MIT