ISIN to LEI mapping

Within the world of hundreds of thousands of companies, two primary identifiers are used in finance. The first is The International Securities Identification Number, otherwise known as ISIN, and the second is The Legal Entity Identifier, an LEI.

These identifiers have a lot in common. They’re both used to increase transparency and are made up of alphanumeric digits with check numbers. The difference between them lies in their purpose. Combining the two codes, known as ISIN to LEI mapping, it’s now possible to map out the global financial system and bring a level of security to the markets that used to be unimaginable.


The International Securities Identification Number (ISIN)

ISIN was first introduced in 1981, but it took another decade to be fully endorsed after the G30 countries’ recommendation. The ISIN number (structure defined in ISO 6166) is a globally recognised identifier used for identifying particular financial instruments like securities, bonds, stocks, trusts, and futures, to name a few. In 2004, the European Union mandated the use of instrument identifiers in some of its regulatory reporting, which included ISIN as one of the valid identifiers. The ISIN is an extended version of the US Committee on Uniform Security Identification Procedures (CUSIP number).

From there, nations,  specifically in the EU, adopted the ISIN as its primary identification number for financial instruments. An ISIN can be obtained from National Numbering Agencies (NNAs). The Association of Numbering Agencies (ANNA) is the overseeing Registration Authority of the ISIN. It is devoted to using standard identifiers to create a safer, more stable, and more efficient environment for investors and the financial institutions that serve them.

The ISIN code consists of 12 characters:

  • The first two characters are taken up by the alpha-2 country code as issued under the international standard ISO 3166 of the country where the issuer of securities (other than debt securities) is registered or in which it has legal domicile. In the case of depository receipts, such as American Depository Receipts (ADRs), the country code is the organisation that issued the receipt, not the one that gave the underlying security.

  • The local numbering code of the security concerned takes up the following nine characters. When the national number is less than nine characters, zeros are put instead to fill the nine spaces used.
  • The final character is a check digit computed using the modulus 10 “Double-Add-Double” formula.


    For ISINs of the OTC derivatives, which a single global numbering agency will allocate, the initial two digits use a custom “EZ” code. The ISIN will be generated de novo without referencing previous or other codes.

The Legal Entity Identifier (LEI)

The Global LEI System (GLEIS) grew out of the 2008 Global Financial Crisis (GFC) when the need for greater transparency and security became apparent. GLEIS ensures straightforward, unambiguous identification of participants in financial transactions. The basis of GLEIS is ISO 17442, developed by the International Organization for Standardization (ISO). This standard defines the details of clear legal recognition for identifying the relevant legal identities taking part in a financial transaction. So this time, the identifier was not used for identifying financial instruments, but the market participants involved in financial transactions, the legal entities.

Identifying individual entities had been challenging, mainly if that company was international, had multiple branches worldwide, or had complex funding structures. You never knew which one was engaging in any given transaction.

An example of a legal entity that may obtain an LEI code is a limited company or partnership, a Fund, or a Trust – any company listed on a stock exchange or engaging in the transactions of securities (that may possess an ISIN) and OTC Derivatives. Similar to ANNA, The Global Legal Entity Identifier Foundation (GLEIF) is the organisation responsible for implementing the LEI and keeping an eye on the execution of the GLEIS.

Advantages of the Global LEI System

This global system has significant benefits to the economy by providing standardised data on companies trading all over the world. The best part is a public database, accessible to everyone and free of charge  Global LEI Index.

Consequently, the database has greatly simplified dealing with international clients as there’s no need for a time-consuming background check where previously the only information being relied upon was the company’s own internet presence and local registry listings, often leading to hours of translating and web browsing with little confidence of the authenticity. Reducing the risk of fraud and allowing banks to spot money laundering easier and faster.

The LEI code consists of 20 characters:

  • The first four characters are unique to the LOU, which has issued the LEI.
  • The 5th and 6th characters are the same – 0 for every company.
  • The following 12 characters are letters and numbers unique for each company.
  • The final two characters are known as the checking characters.
  • An LEI code will be issued to each company once.

    The code search will reveal crucial information based on the entity’s ownership structure. As such, it can establish  ‘who is who’ and ‘who owns whom.’ LEI search will provide access to a global directory of participants within the financial market.

ISIN to LEI mapping

On 4 September 2018, ANNA and GLEIF launched a new initiative to link ISINs with their corresponding LEIs. Finally, tradable financial assets (securities) can be linked to the legal entities purchasing, issuing, and selling that security. This is recognised as a huge step forward in aggregating the data required to analyse risk exposure accurately. The Financial Stability Board (FBS) and the European Securities and Markets Authority (ESMA) have recently endorsed the initiative. Critical importance lies in the accuracy of the data to operate a successful ISIN to LEI mapping.

GLEIF has established a certification process where organisations can link their LEIs to corresponding ISINs (ISIN to LEI mapping). Early adopters have begun the mapping process that makes the mapped identifiers available for download via CSV or PDF file. Today there are customised data mappings available for banks, insurance companies, and pension schemes. Eventually, this will generate remarkable advantages for the wider business community by simplifying and globalising a method of validating organisations and mapping identifiers. This information, on a greater scale, can be used to understand organisations identity and hierarchy, consequently contributing to newer technological innovations like blockchain.

The daily ISIN to LEI mapping files are publicly available on the GLEIF website and include new ISINs issued by early-mover NNAs. The advantages of ISIN to LEI mapping are enormous. By attaching an LEI to security, finance institutions can distinctly spot trends and analyse odd activities – all while protecting market participants from cases of attempted fraud and market abuse. 

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