TL;DR: A CUSIP is a 9-character code that uniquely identifies a specific U.S. (and Canadian) security. SEC filings like 13F list holdings by CUSIP, not ticker, so working with ownership data means mapping CUSIPs to tickers. The first 6 characters identify the issuer, the next 2 the specific issue, and the last is a check digit.

The structure

A CUSIP is 9 characters: issuer (6) + issue (2) + a check digit (1). Illustrative.

Characters 1-6 (issuer): which company or entity.
Characters 7-8 (issue): which specific security from that issuer (e.g., a particular share class or bond).
Character 9 (check digit): a math check that catches typos.

CUSIP vs ticker vs ISIN

Ticker (e.g., AAPL) is the friendly exchange symbol, but it can be reused or change.
CUSIP is a stable, granular identifier used in filings and settlement.
ISIN is the international 12-character identifier (a country prefix plus, often, the CUSIP).

For holdings analysis, the CUSIP is what you'll actually find in the raw data, and the ticker is what humans want to read.

Why it matters for filings data

13F filings identify every position by CUSIP. To make that data usable you have to resolve CUSIP → ticker → company, handle issues where a CUSIP doesn't cleanly map, and keep up as identifiers change with corporate actions. This resolution work is unglamorous but essential, and it's a big part of why clean ownership data is valuable. (See how to read a 13F filing.)

Frequently asked questions

How many characters is a CUSIP?

Nine: six for the issuer, two for the issue, and one check digit.

Why do 13F filings use CUSIPs instead of tickers?

CUSIPs are stable and unambiguous at the security level; tickers can change or be reused. Filings need precision.

Is a CUSIP the same as an ISIN?

No. An ISIN is a 12-character international ID that often embeds the CUSIP with a country code and its own check digit.

Arkolith resolves CUSIPs to tickers and serves clean, sourced holdings data. Browse the funds or get a key.