Financial Identifier Conversion: The Complete Guide

Last updated: February 2026 · 15 min read

Financial markets use dozens of identifier systems to track securities, entities, and instruments. This comprehensive guide covers every major identifier type, explains how they relate to each other, and provides a practical conversion matrix showing which identifiers can be converted between and how.

The Seven Major Identifiers

The Conversion Matrix

Not all conversions are possible algorithmically. Some require database lookups. Here's the reality:

Key: ✅ Algo = algorithmic conversion possible | 🔍 Lookup = database/API lookup required | ❌ N/A = not applicable (LEI identifies entities, not securities)

How ISIN Wraps National Identifiers

The genius of the ISIN system is that it embeds each country's national identifier inside a universal wrapper:

US ISIN:  US  [CUSIP 9 chars]     [check]   → US0378331005
DE ISIN:  DE  000[WKN 6 chars]    [check]   → DE0007664039
GB ISIN:  GB  00[SEDOL 7 chars]   [check]   → GB0005405286
CH ISIN:  CH  [VALOR padded 9d]   [check]   → CH0038863350
CA ISIN:  CA  [CUSIP 9 chars]     [check]   → CA7800871021
JP ISIN:  JP  [Securities Code]   [check]   → JP3633400001

This design means that for same-country conversions, you can extract the national identifier algorithmically. For cross-country conversions (e.g., US ISIN → German WKN), you always need a database lookup.

Algorithmic Conversions

ISIN → National Identifier

• US/CA ISIN → CUSIP: Characters 3–11
• DE ISIN → WKN: Characters 6–11
• GB ISIN → SEDOL: Characters 5–11
• CH ISIN → VALOR: Characters 3–11, strip leading zeros

National Identifier → ISIN

Reverse the process: add country code, pad with zeros, calculate Luhn check digit.

Database Lookup Methods

For non-algorithmic conversions, you need a data source:

Identifier by Use Case

The History: Why So Many?

The proliferation of identifiers is a product of history. Each system was created by a different organization at a different time:

Frequently Asked Questions

Which identifier should I use if I can only pick one?

ISIN. It's the most universally accepted, works across borders, embeds national identifiers, and is used in virtually all regulatory frameworks. For US-only applications, FIGI is a strong alternative (free, more granular).

Are there identifiers for other asset classes?

Yes. ISINs cover equities, bonds, ETFs, and some derivatives. For OTC derivatives, the UTI (Unique Transaction Identifier) and UPI (Unique Product Identifier) are used. For funds, there's also the CFI (Classification of Financial Instruments) code. Currencies use ISO 4217 codes (EUR, USD, GBP).

Will these ever be unified into one system?

Unlikely. ISIN is the closest to universal, but CUSIPs persist due to deep integration in US infrastructure, WKNs due to German financial culture, and SEDOLs due to UK market practices. FIGI was an attempt at unification but has become yet another identifier alongside the others. The cost of migration is too high for any single system to replace all others.

How do I handle securities with multiple identifiers in my database?

Best practice: use ISIN as your primary key. Create a mapping table with columns for CUSIP, WKN, SEDOL, VALOR, FIGI, and ticker. Populate via OpenFIGI API or your data vendor. Index all columns for fast lookup by any identifier type.