How to Find a Stock's CUSIP, and When It Actually Changes

A stock's CUSIP is a 9-character code that identifies the specific security, not the company's ticker symbol and not the company itself if it has more than one class of stock. If you are holding a stock and need its CUSIP for a transfer, a cost basis form or a 13F cross-check, the fastest free source is the security's own SEC filings, since the number is printed on cover pages throughout EDGAR.

This guide covers what the characters in a CUSIP mean, where to find one for a specific stock, and the one thing most explainers skip: CUSIPs are not permanent the way tickers can feel permanent, and a real corporate reorganization is proof.

What a stock's CUSIP actually looks like

A CUSIP (Committee on Uniform Securities Identification Procedures number) is 9 characters, split into three parts:

• Characters 1 to 6: the issuer number, assigned to the company or entity.
• Characters 7 and 8: the issue number, identifying the specific class of security (common stock, a preferred series, a specific bond).
• Character 9: a check digit, computed from the other 8 characters using a fixed formula (a weighted sum, alternating multipliers of 1 and 2, modulo 10). A tool that only checks the length of a code without validating this digit will accept typos.

Apple's common stock CUSIP is 037833100: issuer number 037833, issue number 10, check digit 0. If Apple ever issued a separate preferred class, it would carry the same issuer number with a different issue number.

Where a stock's CUSIP shows up in SEC filings

Because 13F filings report a CUSIP for every position every quarter, they are one of the most reliable free, repeating sources for a specific stock's CUSIP if the stock is held by large institutional managers.

Finding the CUSIP for a specific stock you hold

1. Check your brokerage statement or trade confirmation. Most brokers print the CUSIP for each position you hold, since they need it to settle the trade.
2. Search EDGAR full text search for the company name plus "CUSIP." Prospectuses, 13D/13G cover pages and 13F filings that hold the stock will surface it.
3. Use a one-off CUSIP lookup tool if you only need a single, well known large-cap stock's CUSIP. What a CUSIP number actually is covers the free lookup options and their coverage limits, since most of them only reach securities large managers actually reported holding, not every bond or thinly traded security.

Why a stock split does not change its CUSIP, but a reorganization can

A forward or reverse stock split changes the number of shares outstanding and the price per share, but it does not change the underlying security's identity, so the CUSIP stays the same. What does change a CUSIP is anything that changes the legal issuer itself: a merger into a new holding company, a reincorporation that creates a new entity, or a reorganization where shareholders receive stock in a different legal person than the one they originally held.

A common simplification treats a stock's CUSIP as effectively permanent once assigned. That holds only as long as the company issuing the stock does not itself change, and large, well known reorganizations show it does not always hold.

A real example: Google's CUSIP after becoming Alphabet

On October 2, 2015, Google Inc. completed a holding company reorganization under Exchange Act Rule 12g-3, becoming a subsidiary of a new parent, Alphabet Inc. Google filed a Form 8-K that day (accession 0001193125-15-336550) and Alphabet filed its own Form 8-K12B (accession 0001193125-15-336577) establishing Alphabet as the successor issuer; a Form 25-NSE (accession 0001354457-15-000182) was filed the same day as part of the transition.

The CUSIP changed with the entity. Checking Form 13F filings for the same institutional holder across the transition shows it directly: Vanguard's Q3 2015 13F reported "GOOGLE INC" under CUSIPs 38259P508 and 38259P706 (Class C and Class A shares), and its Q4 2015 13F reported the same underlying shares as "ALPHABET INC" under new CUSIPs 02079K305 and 02079K107. The shares kept trading through the reorganization; the CUSIP did not survive it, because the issuer on record changed from Google Inc. to Alphabet Inc.

Looking up CUSIP data in code

For a single CUSIP, SecFeed resolves it to the issuer and ticker as reported across 13F filings:

curl "https://secfeedapi.com/v1/mapping/cusip?cusip=037833100" \
  -H "Authorization: Bearer YOUR_API_KEY"

{
  "cusip": "037833100",
  "issuer": "APPLE INC",
  "ticker": "AAPL",
  "cik": "320193"
}

To go the other direction and see every CUSIP ever reported for a given company, including ones that stopped being used after a reorganization like Alphabet's, query the 13F holdings data by CIK and look at the distinct CUSIPs across quarters:

from secfeed import Client

sf = Client("YOUR_API_KEY")
rows = sf.holdings_13f(cik="1652044")  # Alphabet Inc.
cusips = sorted({r["cusip"] for r in rows if r["cusip"]})
print(cusips)

Mapping a CUSIP to a ticker and CIK walks through this join in more detail, and 13F holders by CUSIP shows the reverse lookup: every manager holding a given security in a given quarter.

CUSIP vs ticker vs ISIN

A US security's ISIN is typically built from its CUSIP (US plus the CUSIP plus a check digit), so a change to one usually means a change to the other.

Frequently asked questions

Is a CUSIP the same as a ticker symbol?

No. A ticker identifies how a stock trades on an exchange and can be short, memorable and sometimes reused after a delisting. A CUSIP identifies the specific security and class, independent of where or whether it currently trades.

Does every stock have a CUSIP?

Most US and Canadian publicly traded securities have one, assigned when the security is created. Some foreign securities trading only outside North America use an ISIN without a CUSIP as their primary identifier.

Can two different stocks share a CUSIP?

No. CUSIPs are unique to a security and class. If you see what looks like the same CUSIP on two different companies, check the check digit and issue number carefully, since CUSIPs for separate issuers do not legitimately collide.

Why did my broker show a different CUSIP for the same company I remember?

If the company went through a merger, holding company reorganization or similar restructuring, the issuing entity changed even though the shares you hold kept trading under the same or a similar name. The Google to Alphabet reorganization is a documented example of exactly this.

Where can I verify a CUSIP for free?

EDGAR full text search and the underlying 13F, 13D/13G and prospectus filings are free and do not require a CUSIP Global Services subscription. How to find your CUSIP number walks through the free options and their coverage limits in more detail.