Skip to content
All library documents

SEC Central Index Keys Are Permanent Identifiers

Article Quant Q&A · Author: Till Hoffmann
Read the original

Summary

The document answers whether the SEC can give a former registrant’s Central Index Key to a later company. It states that CIKs are unique over time and are not reassigned or recycled after an entity ceases to exist. For financial researchers, this establishes that a CIK can serve as a persistent identifier when linking SEC filings across time, including periods after a registrant has disappeared.

The support cited is a response attributed to someone who contacted the SEC, quoted in an answer to the original question. The document does not describe the SEC’s identifier assignment process, provide formal documentation, or discuss how to handle mergers, name changes, subsidiaries, or other entity-resolution complications. Its claim is specifically about CIK reuse; it should not be taken to mean that a CIK alone resolves every question about corporate identity across filings.

Key ideas

  • The document states that SEC Central Index Keys are not reassigned after a registrant ceases to exist.
  • It presents CIKs as identifiers intended to remain unique over time.
  • Persistent identifiers can help researchers link filings across dates.
  • The cited answer does not address other corporate identity and entity-resolution issues.

Tags

EquitiesUS markets
Full text
# Can Central Index Keys (CIKs) issued by the SEC be reassigned?


# Can Central Index Keys (CIKs) issued by the SEC be reassigned?












Suppose company A has CIK 0000012345 and ceases to exist. At some later time, company B registers with the SEC to submit filings.

Is it possible that company B will be assigned the same CIK 0000012345? In other words, are CIKs unique for all time or are CIKs unique at any instant of time?

## Answer by Till Hoffmann (score 1, accepted)

https://quant.stackexchange.com/a/7782

I have been in touch with the securities and exchange commission. CIKs cannot be reassigned and are unique for all time. See the excerpt below:

> CIKs are not reassigned or recycled by the SEC -- they are intended to be forever unique.

Shown in full with attribution under the source's licence. Licence: CC BY-SA 4.0 (Stack Exchange)

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.