The Global Companies Database sources ISINs from an ISIN-LEI mapping file from ANNA (Association of National Numbering Agencies).
The file is sourced daily and contains an ISIN to LEI relationship for NNAs (National Numbering Agencies) that have opted into the project. The current coverage is over 4.5 million ISINs. You can read more about the project here.
As more NNAs opt in, the ISIN coverage in GCD will increase and these will be automatically added into the dataset.
The current NNAs that have opted in are:
Austria Oesterreichische Kontrollbank Aktiengesellschaft (OeKB)
Belgium SIX Financial Information Belgium S.A./N.V.
Czech Republic Centrální depozitář cenných papírů, a.s. – Central Securities Depository
Germany WM Datenservice
Iceland Nasdaq CSD Iceland hf
Italy Banca d´Italia
Japan Tokyo Stock Exchange
Malta Malta Stock Exchange PLC
Nigeria Central Securities Clearing System Plc.
Poland Central Securities Depository of Poland (KDPW SA)
Romania Depozitarul Central S.A. (Romanian Central Depository)
Slovenia KDD Central Securities Clearing Corporation
South Africa JSE Ltd – NEW as of April 16, 2020
Spain Comisión Nacional del Mercado de Valores (CNMV)
Sweden Euroclear Sweden AB
Switzerland SIX Financial Information Ltd
Turkey Istanbul Takas ve Saklama Bankası A.S.- Takasbank
United Kingdom London Stock Exchange
USA CUSIP Global Services
In addition to the jurisdictions outlined above also ISIN-LEI-Links are provided for Jersey, Guernsey, Isle of Man and Liechtenstein.