International Securities Identification Number

An International Securities Identification Number (ISIN) uniquely identifies a security. Its structure is defined in ISO 6166. Securities for which ISINs are issued include bonds, commercial paper, stocks and warrants. The ISIN code is a 12-character alpha-numerical code that does not contain information characterizing financial instruments but serves for uniform identification of a security at trading and settlement.

Securities to which ISINs can be issued include debt securities, shares, options, derivatives and futures. The ISIN identifies the security, not the exchange (if any) on which it trades; it is not a ticker symbol. For instance, Daimler AG stock trades through almost 30 trading platforms and exchanges worldwide, and is priced in five different currencies; it has the same ISIN on each, though not the same ticker symbol. ISIN cannot specify a particular trading location in this case, and another identifier, typically MIC (Market Identification Code) or the three-letter exchange code, will have to be specified in addition to the ISIN. The Currency of the trade will also be required to uniquely identify the instrument using this method.

Description

An ISIN consists of three parts: Generally, a two letter country code, a nine character alpha-numeric national security identifier, and a single check digit. The country code is the ISO 3166-1 alpha-2 code for the country of issue, which is not necessarily the country where the issuing company is domiciled. International securities cleared through Clearstream or Euroclear, which are worldwide, use "XS" as the country code.

Issuance

The ISIN is based on the National Securities Identifying Number, or NSIN, assigned by governing bodies in each country, known as the national numbering agency (NNA). The NNAs are co-ordinated through the Association of National Numbering Agences, ANNA. ISIN and CFI information can be accessed through the ANNA Service Bureau (ASB), run by CUSIP Global Services and SIX Financial Information. The ASB has the complete ISIN database of record but can only be accessed for a fee.

The NSIN element of the ISIN can be up to 9 digits long. Shorter numbers are padded with leading zeros before the addition of the country code and a check digit transform the NSIN to an ISIN.

In the United States the NNA is the CUSIP organization, meaning that CUSIPs can easily be converted into ISINs by adding the US country code to the beginning of the existing CUSIP code and adding another check digit at the end. In Canada, the NNA is CDS Solutions. In the United Kingdom and Ireland the NNA is the London Stock Exchange and the NSIN is the SEDOL, converted in a similar fashion. Swiss ISINs are issued by SIX Financial Information and are based on the VALOR number. Most other countries use similar conversions, but if no country NNA exists then regional NNAs are used instead.

ISINs are being introduced worldwide. At present, trading, clearing and settlement systems in many countries have adopted ISINs as a secondary measure of identifying securities. Some countries, mainly in Europe, have moved to using the ISIN as their primary means of identifying securities. In addition new European regulations such as Solvency II increasingly require the ISIN to be reported.

Commercial Model

The ISIN is generally included in services sold by financial data vendors. These services are normally paid services as more, value add data is included with the information. In general, the issuer of a security may include the ISIN in issuance papers or other documentation for identifcation purposes.

Some services will promise to allocate an ISIN for a fee. However this service will simply be contacting the relevant NNA. The Association of National Numbering Agencies (ANNA) is ISO's appointed registration authority and the only way to obtain a real ISIN without paying additional fees is to approach an ANNA-appointed NNA.

Controversy

As an ISO standard code, the ISIN was designed to be made freely available to users. This is not quite the case. To obtain an ISIN, an issuer - or other body - must request that an NNA issues the underlying NSIN. The NNA may charge for this facility.

In addition, the usage of the code should be free of charge. Standard and Poor's in 2009 was formally charged by the European Commission (EC) with abusing its position as the sole provider of international securities identification codes for United States of America securities by requiring European financial firms and data vendors to pay licensing fees for their use. "This behaviour amounts to unfair pricing," the EC said in its statement of objections which lays the groundwork for an adverse finding against S&P. "The (numbers) are indispensable for a number of operations that financial institutions carry out – for instance, reporting to authorities or clearing and settlement – and cannot be substituted.”

S&P has run the CUSIP Service Bureau, the only ISIN issuer in the US, In its formal statement of objections, the EC alleged "that S&P is abusing this monopoly position by enforcing the payment of licence fees for the use of US ISINs by (a) banks and other financial services providers in the EEA and (b) information service providers in the EEA." It claimed that comparable agencies elsewhere in the world either do not charge fees at all, or do so on the basis of distribution cost, rather than usage.

In 2011, Standard and Poor's provided six undertakings to the European Union to remedy the situation. The full wording of the agreement can be seen here and is applicable to all consuming companies in the European Union.

ISIN Calculation Methodology

The procedure for calculating ISIN check digits uses the Luhn algorithm, a "Modulus 10 Double Add Double" technique also used in CUSIPs and SEDOLS. The Luhn algorithm was designed for numbers, but an ISIN contains letters as well, so letters must be translated to numbers before the checksum is calculated.

To calculate the check digit, first convert any letters to numbers by adding their ordinal position in the alphabet to 9, such that A = 10 and M = 22. Starting with the right most digit, every other digit is multiplied by two. (For CUSIP check digits, these two steps are reversed.) The resulting string of digits (numbers greater than 9 becoming two separate digits) are added up. Subtract this sum from the smallest number ending with zero that is greater than or equal to it: this gives the check digit, which is also known as the ten's complement of the sum modulo 10. That is, the resulting sum, including the check-digit, is a multiple of 10.

Conversion table for characters is:

A = 10	F = 15	K = 20	P = 25	U = 30	Z = 35
B = 11	G = 16	L = 21	Q = 26	V = 31
C = 12	H = 17	M = 22	R = 27	W = 32
D = 13	I = 18	N = 23	S = 28	X = 33
E = 14	J = 19	O = 24	T = 29	Y = 34

In other words; Take the ASCII code for the capital letter and subtract 55

Examples

Apple Inc.

Apple Inc.: ISIN US0378331005, expanded from CUSIP 037833100 The main body of the ISIN is the original CUSIP, assigned in the 1970s. The country code "US" has been added on the front, and an additional check digit at the end. The country code indicates the country of issue. The check digit is calculated in this way.

Convert any letters to numbers:

U = 30, S = 28. US037833100 -> 3028037833100.

Collect odd and even characters:

3028037833100 = (3, 2, 0, 7, 3, 1, 0), (0, 8, 3, 8, 3, 0)

Multiply the group containing the rightmost character (which is the FIRST group) by 2:

(6, 4, 0, 14, 6, 2, 0)

Add up the individual digits:

(6 + 4 + 0 + (1 + 4) + 6 + 2 + 0) + (0 + 8 + 3 + 8 + 3 + 0) = 45

Take the 10s modulus of the sum:

45 mod 10 = 5

Subtract from 10:

10 - 5 = 5

Take the 10s modulus of the result (this final step is important in the instance where the modulus of the sum is 0, as the resulting check digit would be 10).

5 mod 10 = 5

So the ISIN check digit is five.

Treasury Corporation of Victoria

TREASURY CORP VICTORIA 5 3/4% 2005-2016: ISIN AU0000XVGZA3

Convert any letters to numbers:

A = 10, G = 16, U = 30, V = 31, X = 33, Z = 35. AU0000XVGZA -> 103000003331163510.

Collect odd and even characters:

103000003331163510 = (1, 3, 0, 0, 3, 3, 1, 3, 1), (0, 0, 0, 0, 3, 1, 6, 5, 0)

Multiply the group containing the rightmost character (which is the SECOND group) by 2:

(0, 0, 0, 0, 6, 2, 12, 10, 0)

Add up the individual digits:

(1 + 3 + 0 + 0 + 3 + 3 + 1 + 3 + 1) + (0 + 0 + 0 + 0 + 6 + 2 + (1 + 2) + (1 + 0) + 0) = 27

Take the 10s modulus of the sum:

27 mod 10 = 7

Subtract from 10:

10 - 7 = 3

Take the 10s modulus of the result (this final step is important in the instance where the modulus of the sum is 0, as the resulting check digit would be 10).

3 mod 10 = 3

So the ISIN check digit is three.

Check-digit flaw in ISIN

The Treasury Corporation of Victoria ISIN illustrates a flaw in ISIN's check digit algorithm which allows transposed letters: Suppose the ISIN was mis-typed as AU0000VXGZA3

A = 10, G = 16, U = 30, V = 31, X = 33, Z = 35. AU0000VXGZA -> 103000003133163510.

Collect odd and even characters:

103000003133163510 = (1, 3, 0, 0, 3, 3, 1, 3, 1), (0, 0, 0, 0, 1, 3, 6, 5, 0)

Multiply the group containing the rightmost character (which is the SECOND group) by 2:

(0, 0, 0, 0, 2, 6, 12, 10, 0)

Add up the individual digits:

(1 + 3 + 0 + 0 + 3 + 3 + 1 + 3 + 1) + (0 + 0 + 0 + 0 + 2 + 6 + (1 + 2) + (1 + 0) + 0) = 27

Take the 10s modulus of the sum:

27 mod 10 = 7

Subtract from 10:

10 - 7 = 3

Take the 10s modulus of the result (this final step is important in the instance where the modulus of the sum is 0, as the resulting check digit would be 10).

3 mod 10 = 3

So the ISIN check digit is still three even though two letters have been transposed.

BAE Systems

BAE Systems: ISIN GB0002634946', expanded from SEDOL ' 000263494

The main body is the SEDOL, padded on the front with the addition of two zeros. The country code "GB" is then added on the front, and the check digit on the end as in the example above.

External links

• Javascript code for ISIN validation
• Code for ISIN in several programming languages on Rosetta Code site
• International Organisation for Standardization ISIN