SEDOL stands for Stock Exchange Daily Official List, a list of securities identifiers used for clearing purposes in the United Kingdom and Ireland.

On the request of the securities issuer, the London Stock Exchange assigns the numbers.

SEDOLs are used as the National Securities Identifying Number (NSIN) for all securities issued in the United Kingdom, and are thus included in the ISIN.

The SEDOL Masterfile (SMF) contains reference data on millions of multi-asset securities from around the world, each of which is uniquely identifiable at the market level by a universal SEDOL code.

SEDOLs are seven characters long and are made up of two parts: a six-place alphanumeric code and a check digit at the end.

[1] Prior to January 26, 2004, SEDOLs were simply made up of numbers.

SEDOLs from Asia and Africa usually start with 6 for older SEDOLs.

Those from the United Kingdom and Ireland (before Ireland joined the EU) usually start with a zero or a three.

Those from the rest of Europe usually started with four, five, or seven.

Those from the Americas started with number two.

SEDOLs became alpha-numeric after January 26, 2004, and are issued progressively, starting with B000009.

Numbers come before letters in each character place, and vowels are never utilised.

As a result, all new SEDOLs begin with a letter.

End user allocation is reserved for ranges beginning with 9.

For a SEDOL, the check digit is chosen so that the total weighted sum of all seven characters is a multiple of ten.

A weighted sum of the first six characters is used to get the check digit.

B = 11 and Z = 35, for example, have a value of 9 plus their alphabet position.

While vowels are never used in SEDOLs, they are not discarded while computing this weighted sum (e.g., H = 17 and J = 19, despite the fact that I is not used), making the method to compute this sum simpler.

The weighting factor is then multiplied by the resulting string of numbers as follows:

+ First weight: 1

+ Second weight: 3

+ Third weight: 1

+ Fourth weight: 7

+ Fifth weight: 3

+ Sixth weight: 9

+ Seventh 1 (the check digit)

The weights are multiplied by the character values.

The check digit is chosen to make the overall sum, including the check digit, a multiple of 10, which can be calculated as (10 (weighted sum modulo 10)) modulo 10 from the weighted sum of the first six characters.

SEDOLs are transformed to ISINs for British securities by padding the front with two zeros, then adding the country code and the ISIN check digit at the end.

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