What is a CIK number?
A CIK (Central Index Key) is the unique, permanent number the SEC assigns to every filer — the stable identifier behind a company, even when its ticker changes.
The permanent ID behind every filer
A CIK — Central Index Key — is the unique number the SEC assigns to every entity that files through EDGAR: companies, funds, and individuals. Once assigned, a CIK never changes.
Why it matters
Tickers and company names are not stable identifiers. A company can change its ticker, rebrand, merge, or be acquired — but its CIK stays the same. That makes the CIK the reliable key for tracking a filer's history across all of those changes.
This is why FiledFeed keys companies on their CIK internally. Tickers are treated as attributes that can come and go; the CIK is the anchor. It's also why a company's page works whether you arrive by ticker (/company/aapl) or by CIK (/company/320193) — both resolve to the same entity, and the CIK form redirects to the canonical ticker URL.
What it looks like
A CIK is just a number, often shown zero-padded to ten digits (for example, Apple's 0000320193). You'll see it on every company page and in the address of the underlying SEC filings. Each individual filing also has its own accession number.