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CUSIP vs CIK

CUSIP and CIK are the two identifiers that show up everywhere in SEC filings, and they identify two completely different things. Mixing them up is the single most common bug in early-stage EDGAR pipelines.

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The one-paragraph answer

A CUSIP identifies a security (a specific stock, bond, or class of share). A CIK identifies a filer (a person or entity that submits documents to the SEC). One company has exactly one CIK but may have multiple CUSIPs (one per class of stock, one per debt issue, etc.). A single CUSIP belongs to one and only one company.

CIK: Central Index Key

A CIK is the SEC's internal identifier for any party that has ever filed with EDGAR. Public companies have CIKs. Hedge funds have CIKs. Officers and directors who file Form 4 have CIKs. Auditors who file consent letters have CIKs.

CIKs are 10-digit numbers, padded with leading zeros when written formally. The CIK for Apple Inc. is 0000320193. In API parameters and URL paths you often see them without the leading zeros: 320193.

Properties:

  • Stable for life. A company keeps the same CIK from its first filing until it deregisters. Even if the ticker changes (rebrand, M&A), the CIK does not.
  • Unique per filer. No two filers share a CIK.
  • Granted by the SEC. You can't choose your own CIK; it's issued on first filing.
  • Searchable via EDGAR. The EDGAR company search returns CIKs directly.

A CIK is the right identifier when:

  • You want to pull all filings by a specific entity (regardless of which security).
  • You're linking a Form 4 filer (a person) to their other filings.
  • You're aggregating across an entity's entire SEC history.

CUSIP: Committee on Uniform Securities Identification Procedures

A CUSIP is a 9-character identifier for a specific security. The first 6 characters identify the issuer, the next 2 characters identify the security type (common stock, preferred, debt class), and the last character is a checksum.

Examples:

  • 037833100, Apple Inc. Common Stock
  • 594918104, Microsoft Corp. Common Stock
  • 67066G104, Nvidia Corp. Common Stock

Properties:

  • Issued by CUSIP Global Services, not the SEC. They are commercial identifiers.
  • One security per CUSIP. Apple common stock has its own CUSIP. Apple's various bond issues each have separate CUSIPs.
  • Used heavily in 13F filings because institutions report holdings by security, not by issuer.
  • Not free in bulk. The CUSIP Service Bureau charges commercial users for the full database. The SEC includes them in 13F filings, so you can build a CUSIP-to-issuer map for the universe of 13F-eligible securities by parsing those filings.

A CUSIP is the right identifier when:

  • You're working with 13F holdings data.
  • You're matching positions across data providers.
  • You need to disambiguate between two share classes of the same issuer (Class A vs Class B).
  • You're integrating with brokerage feeds.

The mapping problem

The SEC has a CIK for every issuer but does not natively publish a CUSIP for each. CUSIPs only show up in filings that need them: 13Fs, certain 13D/G filings, prospectuses. To map a CUSIP to a CIK you have to:

  1. Look up the issuer name in the 13F line item.
  2. Match that issuer name to a CIK via the EDGAR company database.
  3. Handle the fact that issuer names in 13F filings are inconsistent (APPLE INC vs APPLE INC. vs Apple, Inc.).

This is a real engineering project. Many teams build their own mapping table and rebuild it quarterly when new 13Fs land.

EdgarKit handles this automatically: every 13F line item is returned with the CUSIP and the resolved ticker and the issuer CIK. The mapping is maintained internally and updated as new filings normalize the names.

# 13F line items for Berkshire Hathaway's most recent filing
curl "https://api.edgarkit.com/v1/filings?form_type=13F-HR&manager_cik=1067983&limit=1" \
  -H "Authorization: Bearer YOUR_API_KEY"

Each holding line in the response includes the CUSIP, the resolved ticker, the issuer name, the issuer CIK, value, and shares.

Ticker vs CUSIP vs CIK

Three identifiers for closely related things. Quick reference:

| Identifier | Identifies | Example (Apple) | Stable? | |---|---|---|---| | Ticker | Trading symbol | AAPL | No. Can change on rebrand or relisting. | | CIK | Filer entity | 0000320193 | Yes. Lifetime stable. | | CUSIP | Specific security | 037833100 (common stock) | Yes for that security; bonds and classes have their own. |

Tickers are useful for human-readable display. CIKs are useful for SEC filing aggregation. CUSIPs are useful for security-level work, especially 13F holdings. A robust EDGAR pipeline tracks all three and resolves between them.

Common pitfalls

  • Confusing CUSIP issuer prefix with the full CUSIP. The 6-character prefix identifies the issuer; the full 9-character string identifies a specific security. People sometimes truncate to 6 characters and lose the security distinction.
  • Assuming one CUSIP per company. Companies with multiple share classes (Google's GOOG and GOOGL, Berkshire's BRK.A and BRK.B) have separate CUSIPs.
  • Using ticker as a primary key. Tickers change. Apple was once AAPL on NASDAQ but the legal entity behind it has had many name and exchange variants over decades. The CIK never changed.
  • Trying to bulk-download the full CUSIP database. It's commercially licensed. Build your map from 13F filings instead.

FAQ

Can two companies share a CIK?

No. Each CIK is unique to one filer. Mergers create new arrangements (the surviving entity keeps its CIK; the absorbed entity's CIK becomes inactive but is never reissued).

Can two securities share a CUSIP?

No. Each CUSIP is unique to one security. Even if a company issues a new class of stock that looks identical economically, it gets a new CUSIP.

What about ISIN?

ISIN is the international equivalent of CUSIP. A US CUSIP can be converted to an ISIN by prepending US and appending a checksum digit. ISINs are common in international fillings and are the default identifier outside North America.

Does the SEC publish a free CUSIP-to-issuer map?

Not directly. The full CUSIP database is commercially licensed by CUSIP Global Services. You can build a partial map by parsing the issuer name and CUSIP fields from 13F filings, which cover most institutional-grade equities.

Which one should my system use as the primary key?

Use CIK for filer-level aggregation, CUSIP for security-level holdings work, and ticker only for human-readable display. Most production systems carry all three and resolve between them with a lookup table.