What is ISIN Number

The International Securities Identification Number (ISIN) was introduced in the late 1980s to address the growing complexity of cross-border securities trading and settlement. Before its adoption, different countries used their own security identifiers, which made global clearing and reconciliation more difficult. To create a common standard, the International Organization for Standardization (ISO) developed the ISIN framework under ISO 6166. The system was formally implemented in 1990, with National Numbering Agencies (NNAs) assigned responsibility for issuing ISINs within their respective jurisdictions. Since then, ISINs have been adopted across global financial markets, supporting the standardised identification of equities, bonds, funds, and other financial instruments across exchanges, depositories, and settlement systems.

The International Securities Identification Number (ISIN) is a standardised identification code assigned to financial instruments such as equities, debt securities, and fund units. It is issued in accordance with the ISO 6166 standard and is used by market infrastructure institutions in multiple countries. Unlike ticker symbols, which are exchange-specific, an ISIN code remains the same for security across markets.

An ISIN code follows a 12-character format made up of three parts:

• Country code – The first two letters, based on ISO 3166 (for example, IN for India, US for the United States).

• NSIN (National Securities Identifying Number) – The next nine characters assigned by the national numbering agency for that security.

• Check digit – The final character, calculated using a standard algorithm to validate the code.
   

This format allows the ISIN number to be processed consistently across clearing and settlement systems.

Example of ISIN Number

For example, Apple Inc.’s ISIN number is US0378331005:
US = Country code
037833100 = NSIN
5 = Check digit

This ISIN code identifies Apple’s listed equity across exchanges and market systems.

An International Securities Identification Number (ISIN) is assigned when a financial instrument is issued and admitted into a country’s recognised securities infrastructure. The allocation is handled by the National Numbering Agency (NNA) of the issuer’s home jurisdiction, following the ISO 6166 standard. In India, this role is performed by depositories such as NSDL and CDSL, which issue ISINs once a security meets regulatory and depository requirements. The assigned ISIN is then embedded into trading, clearing, and settlement systems so that the instrument can be accurately identified across exchanges, custodians, and market participants. Once allotted, the ISIN becomes the permanent reference for that specific security unless a corporate restructuring event requires reclassification.

The International Securities Identification Number (ISIN) is designed to provide a standardised and reliable way to identify securities across global financial systems. Its structure and allocation framework are governed by internationally accepted norms, allowing securities to be tracked and processed consistently across markets, depositories, and trading platforms.

Key characteristics of an ISIN include:

• Globally standardised format of 12 alphanumeric characters defined under ISO 6166

• Country-based identification, where the first two letters indicate the issuing country

• Security-level uniqueness, ensuring no two instruments share the same ISIN

• Embedded validation, using a check digit to detect data entry or transmission errors

• Issuer-agnostic usage, allowing the same ISIN to be used across exchanges, brokers, and settlement systems
   

These characteristics enable accurate identification and processing of securities throughout their lifecycle, from issuance to trading, settlement, and regulatory reporting.

ISINs are used across financial markets for several operational and regulatory purposes:

• Standardised identification – A single ISIN number is used to reference a security across exchanges, depositories, and clearing systems.

• Trade processing and settlement – ISIN codes are used by clearing corporations and custodians when matching and settling trades.

• Operational accuracy – Using a uniform security identifier reduces ambiguity in transaction records.

• Regulatory and reporting use – ISINs are included in exchange filings, depository records, and regulatory disclosures.

The purpose of the International Securities Identification Number (ISIN) is to provide a single, standardised way to identify financial securities across markets, trading systems, and settlement platforms worldwide. Since the same security may be traded on multiple exchanges and through different intermediaries, the ISIN acts as a common reference that ensures each instrument is recognised consistently, regardless of geography or trading venue.

ISINs are used by stock exchanges, clearing corporations, custodians, and regulators to match trades, confirm settlement instructions, and maintain accurate records of securities in electronic form. They also support regulatory reporting and disclosure by linking transactions to a specific security without ambiguity. By functioning as a uniform identification code, the ISIN helps maintain reliability and traceability across global financial infrastructure.

Other identifiers are also used in securities markets, but ISIN functions as the global standard for cross-border identification.

• ISIN vs. CUSIP: CUSIP is a 9-character identifier used mainly in the United States and Canada. In the U.S., the CUSIP forms the middle portion of the ISIN, with a country prefix and check digit added.

• ISIN vs. SEDOL: SEDOL is a UK-based security identifier. In the UK, the SEDOL forms part of the ISIN structure, but this does not apply to all countries.

• ISIN vs. Ticker Symbols: Ticker symbols are exchange-specific and may differ across trading venues, while an ISIN remains the same for security across markets and settlement systems.
   

ISIN vs. CUSIP

CUSIP: A 9-character alphanumeric code used mainly in the United States and Canada.
ISIN: A 12-character code. For U.S. and Canadian securities, the ISIN is formed by adding a two-letter country prefix to the CUSIP and a calculated check digit at the end.
 

ISIN vs. Ticker Symbol

Ticker symbols are exchange-specific and may be reused or changed.

ISINs are designed to uniquely identify a security for settlement and reporting, although a new ISIN may be issued if the security undergoes certain corporate actions.

In India, ISINs are used to identify securities that are issued, held, and transferred in electronic form through the country’s depository system. These codes are allocated and maintained by authorised National Numbering Agencies in line with the ISO 6166 standard. For Indian securities, the ISIN begins with the country code “IN”, followed by a nine-character security identifier and a check digit. Depositories such as NSDL and CDSL assign and manage ISINs for equity shares, debt instruments, mutual fund units, and other marketable securities. Every dematerialised security traded or settled in India is linked to an ISIN, allowing accurate record-keeping, settlement, and regulatory reporting across stock exchanges and depository platforms.

ISIN numbers form a foundational layer within demat account systems, where every security is recorded, tracked, and transferred based on its unique identification code.

In India’s depository framework, securities such as equity shares, bonds, ETFs, and mutual fund units are not stored in demat accounts by name or ticker symbol. Instead, they are held and processed using their respective ISINs as assigned by recognised depositories like NSDL and CDSL. This allows depository participants, clearing corporations, and stock exchanges to identify each instrument in a uniform manner across all platforms.

When an investor buys or sells a security on a stock exchange, the transaction is matched, cleared, and settled using the ISIN linked to that security. The exchange trade file, clearing instructions, and depository credit or debit entries all reference the ISIN, ensuring that the correct instrument is transferred between the buyer’s and seller’s demat accounts.

Corporate actions such as bonus issues, rights issues, mergers, or new security issuances are also processed through ISIN mapping. Whenever a new security is created or an existing one undergoes a structural change, a corresponding ISIN is assigned or updated so that the depository system can reflect the change accurately in investor holdings.

By linking every security to a unique ISIN, the demat system ensures error-free trading and settlement.

ISINs are issued by National Numbering Agencies (NNAs) appointed in each country and coordinated globally by the Association of National Numbering Agencies (ANNA).

For example:

• United States: CUSIP Global Services (CGS)

• India: National Securities Depository Limited (NSDL) and Central Depository Services (India) Limited (CDSL)
  
  

These agencies ensure that every ISIN is unique and issued according to international standards.

An ISIN may change when the underlying security is fundamentally altered. This can occur in situations such as:

• Mergers, demergers, or spin-offs that create a new security

• Conversion of securities (for example, preference shares converting into equity)

• Delisting followed by a fresh re-listing

Routine actions such as stock splits, bonus issues, or dividends generally do not result in a new ISIN.

ISINs are published across the securities ecosystem.

• Where to find:
  ISINs appear in prospectuses, stock-exchange listings, company filings, demat statements, and financial data platforms such as Bloomberg and Reuters.
  

• How ISINs are used:
  ISINs are referenced during trade execution, clearing and settlement, portfolio records, corporate-action processing, and regulatory reporting.

In the depository system, securities are recorded and transferred based on their ISIN, ensuring accurate identification across all transactions.

ISINs provide a standardised way to identify securities across exchanges, depositories, and settlement systems. By assigning a unique code to each instrument, ISINs support accurate trade processing, record-keeping, and regulatory reporting within global financial markets.

This content is for informational purposes only and the same should not be construed as investment advice. Bajaj Finserv Direct Limited shall not be liable or responsible for any investment decision that you may take based on this content.