CIK Number Lookup: What a CIK Is and How to Use It

What a CIK number actually is

CIK stands for Central Index Key. EDGAR, the SEC's electronic filing system, assigns one to every filer the first time that filer registers to submit documents. That includes public companies, institutional investment managers, registered funds, trusts, and individual officers and directors of public companies.

The format is deliberately boring. A CIK is an integer of up to ten digits. There is no embedded meaning, no check digit, and no encoding of entity type, unlike a CUSIP, which packs issuer and issue information into its nine characters. Berkshire Hathaway's CIK is 1067983; in EDGAR's machine-readable endpoints it appears zero-padded to ten digits as 0001067983. Both refer to the same filer, and any decent tooling should accept either form.

Two properties make the CIK the backbone of filings data. First, it is permanent: once assigned, a CIK is never reassigned to a different entity. Second, it survives renames. When a company rebrands or a fund adviser changes its legal name, the CIK stays put and EDGAR records the former names alongside it. A name is a label; the CIK is the identity. If you are building anything that joins filings across time (a holdings history, an insider timeline, a quarter-over-quarter 13F diff), key it on CIK and treat the display name as mutable metadata.

Who gets a CIK: issuers, managers, and people

A common beginner mistake is assuming CIKs belong only to public companies. In reality every party to a filing has one, and a single document often references several.

The layering matters. A Form 4 reporting an executive's stock sale carries at least two CIKs: the issuer's and the reporting owner's. A 13F carries the manager's CIK as the filer, while the holdings inside are identified by CUSIP, not by issuer CIKs. Registered funds add a third layer: the trust files under one CIK, while the individual fund series and share classes get separate series and class identifiers that are not CIKs at all.

So when someone says "look up the fund's CIK," the honest answer is "which entity, exactly?" The adviser that files the 13F, the trust that files N-PORT, and the portfolio manager who sits on a board each have a different one. Our guide to 13F vs 13D vs 13G vs Form 4 walks through which entity files which form, and on which deadline (13F at 45 days after quarter end, Form 4 within 2 business days of the trade).

How to do a CIK number lookup

You have three solid routes, in rough order of formality.

The SEC's own tools come first. EDGAR company search accepts a company name or ticker and returns matching filers with their CIKs and full filing histories. For programmatic use, the SEC publishes a ticker-to-CIK JSON mapping file. It is free and authoritative, but it only maps exchange tickers, so hedge fund advisers (which have no ticker) are not in it.

Name searches on EDGAR work, but they are messy in exactly the way legal names are messy: "L.L.C." versus "LLC," ampersands versus "and," abbreviated words, and clusters of similarly named entities under one group. Search a famous manager's brand and you will often get a list of related filers and have to pick the one that actually submits the forms you care about.

The third route is a resolution API. Arkolith's search endpoint takes a free-text query and returns matching filers with their CIKs:

curl -H "Authorization: Bearer YOUR_KEY" "https://arkolith.com/api/v1/search?q=berkshire"

Once you have the CIK, holdings are one call away:

curl -H "Authorization: Bearer YOUR_KEY" "https://arkolith.com/api/v1/funds/1067983/holdings"

Every row in the response carries provenance back to the SEC accession number it came from, so you (or your agent) can verify any position against the original filing. The quickstart covers minting a key, and the listing endpoint at /api/v1/funds enumerates tracked filers if you would rather browse than search.

CIK vs CUSIP vs ticker

Three identifiers, three different jobs, and conflating them is the root of most bad filings code.

A CIK answers "who filed this?" A CUSIP answers "which security is this?" A ticker answers "what symbol does this trade under right now?" Only the first two appear in raw SEC filings: 13Fs identify holdings exclusively by CUSIP, and reading one without a CUSIP-to-ticker map is nearly useless, as covered in how to read a 13F filing.

The directionality trips people up. NVIDIA the issuer has one CIK, but its securities carry their own CUSIPs, and a ticker can in principle change hands over time. Going from a stock page like NVDA back to filings means hopping from ticker to CUSIP to the positions that reference it, then from filer CIKs to the managers holding them. Tickers are for humans, CUSIPs are for securities, CIKs are for filers. Build your joins accordingly, and never cache a name string as identity.

The manager-change gotcha: one fund, two CIKs

This is where CIK-keyed pipelines quietly break. The CIK belongs to the legal filing entity, and fund brands do not map one-to-one onto legal entities.

The friendly case is a rebrand within the same entity: same CIK, new name, continuous history, with the former name preserved in EDGAR's records. The hostile case is a reorganization. An adviser restructures (a new holding company, a succession after a founder steps back, a jurisdiction change) and the successor entity registers fresh. New CIK, and the filings under the old CIK simply stop. To a naive screen, the old fund looks dead and a brand-new fund appears with zero track record, when economically it is the same book and the same people.

Two more variants are worth knowing. Large groups often file 13Fs from several legal entities at once, so summing "the firm's" holdings means knowing which CIKs belong to the family. Spin-outs cut the other way: a star manager's new firm gets a CIK with no history, correctly, and gluing the old firm's record onto it would be wrong.

There is no official SEC crosswalk that says "CIK A succeeded CIK B." Stitching those histories is entity-resolution work: former-name records, address and signatory overlap, and continuity of the actual portfolio. It is a large part of why a clean leaderboard of institutional investors is harder to build than it looks, and why 13F data accuracy depends as much on entity hygiene as on parsing XML.

Why agents should key on CIK, not names

If you are wiring an LLM agent to filings data, names are the hallucination vector. Ask a model for a generically branded fund's holdings and it has to guess among similarly named firms; ask it for a specific CIK and there is nothing to guess. Resolution should happen once, explicitly, through a search step whose result the agent can show, and every downstream call should use the resolved CIK.

That is how Arkolith's API is shaped. Funds are addressed by CIK in the path, every datapoint carries the accession number of the filing it came from, and the Q1 2026 13F dataset spans 1,824 institutional filers (1.87 million long positions, $53.7 trillion in reported value), each keyed to its EDGAR CIK. A response your agent cannot trace to a CIK plus an accession number is a response it should not assert, a principle unpacked in stop AI hallucinating market data.

One closing habit worth adopting even for human research: whenever you save an analysis of a manager, write the CIK next to the name. Six months later, when the brand has changed or a second entity with a similar name has started filing, the number is the only part guaranteed to still mean what it meant. The SEC's own 13F FAQ is a good companion read on what manager filings do and do not contain.

Frequently asked questions about CIK numbers

Is a CIK number the same as a ticker symbol?

No. A ticker identifies an exchange listing and can change over time, while a CIK identifies a filer on EDGAR and is permanent. Hedge fund managers, who have no ticker at all, are identified only by CIK.

Do CIK numbers ever change or get reused?

No. Once EDGAR assigns a CIK it stays with that legal entity forever and is never recycled. What changes is the name attached to it, which is why filings databases track former names under the same CIK.

How do I find the CIK for a hedge fund?

Use EDGAR's company search with the adviser's legal name, or query a resolution API such as Arkolith's /api/v1/search endpoint. Expect several similarly named entities for big groups; the one submitting 13F-HR forms is the institutional manager you usually want.

Why does one fund manager have multiple CIKs?

Because CIKs attach to legal entities, not brands. A large firm may file from several advisory entities at once, and a reorganization can move the filing obligation to a brand-new entity with a fresh CIK while the old one goes quiet.

This article explains public filings and data concepts. It is not investment advice.