ISIN Validator

ISIN: the global identifier for securities under ISO 6166

The ISIN (International Securities Identification Number) is the 12-character code defined by ISO 6166 to uniquely identify any tradable financial instrument across borders: stocks, corporate and government bonds, commercial paper, ETFs, warrants, depositary receipts, options, futures and structured products. Its purpose is to remove the ambiguity of local tickers such as PETR4 or AAPL, which can collide between exchanges, change after corporate actions or even be reused for different issuers.

An ISIN is allocated by a National Numbering Agency (NNA), the country body authorized by the Association of National Numbering Agencies (ANNA). In Brazil the NNA is B3 (B3 S.A. – Brasil, Bolsa, Balcao); in the US it is CUSIP Global Services; in Germany WM Datenservice; in the UK the London Stock Exchange. ANNA itself operates the global ISIN database and the free ANNA Service Bureau public lookup.

Examples of well-known ISINs: US0378331005 (Apple Inc. common stock), BRPETR3ACNOR9 mapped to BRPETR3 family for Petrobras ON, DE000BASF111 (BASF SE), GB0002374006 (Diageo plc), FR0000131104 (BNP Paribas).

Anatomy of the 12 characters

• Positions 1-2: two-letter country prefix using ISO 3166-1 alpha-2 (US, BR, DE, FR, JP). Supranational issues use XS (Euroclear/Clearstream), EU or XF.
• Positions 3-11: nine-character alphanumeric NSIN (National Securities Identifying Number) allocated by the local NNA. In the US the NSIN is the 9-character CUSIP; in the UK it is the 7-character SEDOL right-padded with zeros.
• Position 12: a single decimal check digit calculated by a modified Luhn algorithm.

Check-digit algorithm step by step

The DV uses Luhn mod 10 after converting letters to numbers. Each letter is replaced by its position in the alphabet plus 9 (A=10, B=11, ..., Z=35). The resulting digit string is then processed right to left: starting from the rightmost digit before the DV, every second digit is doubled; if doubling produces a number greater than 9 the two digits are summed. All digits are added; the DV is the value that brings the sum to the next multiple of 10.

US0378331005
U=30, S=28 -> 3 0 2 8 0 3 7 8 3 3 1 0 0 5
double odd positions from right; sum; DV = (10 - sum mod 10) mod 10

ISIN versus ticker, CUSIP, SEDOL, FIGI and CFI

A ticker like PETR4 or TSLA is exchange-specific, may collide across markets and can be reassigned after delisting. The ISIN is global and uniquely identifies the security itself, but does not say where it trades. To pin down a venue you combine the ISIN with the MIC (Market Identifier Code, ISO 10383) of the exchange, for example XNAS for Nasdaq or BVMF for B3.

• CUSIP: 9-character US/Canada identifier; becomes the NSIN inside a US/CA ISIN.
• SEDOL: 7-character UK identifier; right-padded inside a GB ISIN.
• FIGI (Financial Instrument Global Identifier): Bloomberg-led 12-character open standard, case-sensitive, free of licensing fees via the OpenFIGI API.
• CFI (ISO 10962): 6-letter companion code describing instrument type (equity, bond, derivative, option), voting rights and form.

Use cases in modern finance

• Portfolio reporting: custodians and asset managers consolidate positions across global markets using ISIN as the join key.
• MiFID II in the EU and EMIR in derivatives reporting both require ISIN identification on every trade.
• KYC and AML: ISINs travel through SWIFT MT and ISO 20022 settlement messages.
• ETFs and mutual funds: each share class gets its own ISIN even when based on the same strategy.
• Brazilian fintechs (XP Investimentos, Rico, Nubank Invest, Inter) carry ISINs internally to route international orders and consolidate offshore holdings.

Common pitfalls and limitations

An ISIN that passes the Luhn check is only well-formed. The arithmetic does not prove the security exists, is still issued or is currently listed. Some specific pitfalls:

• Delisting and reuse: ISIN of a delisted security can theoretically be reissued, although NNAs avoid it. Always combine with an issue date.
• Same issuer, many ISINs: ordinary, preferred, ADR, GDR, ETF share classes each have a distinct ISIN.
• Free vs paid lookup: official ANNA Service Bureau and OpenFIGI are free; Bloomberg, Refinitiv Eikon and S&P Capital IQ charge for richer metadata.
• Case sensitivity: ISIN is uppercase; FIGI is case-sensitive — do not mix them in databases.

FAQ

What is the difference between a ticker and an ISIN?

A ticker is local to an exchange and ambiguous globally; an ISIN is unique worldwide and stays attached to the security itself, regardless of where it trades.

Is ISIN lookup free?

The ANNA Service Bureau offers a free lookup with rate limits. OpenFIGI by Bloomberg provides a free public API mapping ISIN to FIGI and tickers. Premium data still requires Bloomberg, Refinitiv or S&P.

Give a Brazilian example.

BRPETR3 is the Petrobras ordinary-share family allocated by B3 (the country prefix is BR, NSIN PETR3ACNOR, DV computed by Luhn).

Does this validator query a live exchange?

No. It runs the ISO 6166 Luhn check in your browser. Nothing leaves your machine, and the result confirms only that the 12 characters form an arithmetically valid sequence.

Can two securities share the same ISIN?

No — by design ISIN is globally unique. However, the same underlying may trade on multiple venues; the ISIN stays the same and the MIC differentiates the venue.