WKN

A WKN (Wertpapierkennnummer, "securities identification number") is the six-character alphanumeric code assigned to securities by Germany's national numbering agency. It is the identifier German investors, brokers and retail platforms use most, appearing alongside or instead of the ISIN on order screens, factsheets aimed at the German market and financial media.

For German-issued securities the WKN sits inside the ISIN: DE000 followed by the six-character WKN and the ISIN check digit. Foreign funds sold in Germany, including Irish and Luxembourg UCITS, are also assigned WKNs even though their ISINs carry IE or LU prefixes, so there is no way to derive those WKNs mechanically.

Why it matters

If your users are in Germany or Austria, some will search by WKN, and marketing material from fund houses distributing there will print it prominently. Any fund tool serving that market needs a WKN-to-ISIN mapping at the input layer. Since one ISIN corresponds to one WKN, the mapping is unambiguous once you have it.

In the API

FundFacts API is keyed on ISIN and does not accept or return WKNs. Map the WKN to an ISIN first (fund house product pages and German exchange listings show both), then request the fund.

json
{
  "isin": "LU1681043599",
  "name": "Amundi MSCI World UCITS ETF",
  "cached": false,
  "generatedAt": "2026-07-01T08:15:00Z"
}

Example response fragment; the WKN itself is not part of the payload.

Common pitfalls

• WKNs were purely numeric until 2003 and have been alphanumeric since; store them as strings and preserve leading zeros.
• A WKN identifies a security, not a listing, so like a SEDOL it does not tell you which exchange a ticker refers to.