As of November 6, 2026, CoStar Group, Inc. is a publicly traded company (Nasdaq: CSGP); its largest reported holder is Vanguard, with 9.12% on Schedule 13G of April 29, 2026, then Vanguard (7.53%). The largest insider holding is Michael R. Klein, a director, with 1,848,592 shares (0.46% of shares outstanding), per Form 4 of December 12, 2024 (Schedule 13G, April 29, 2026).
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Is CoStar Group, Inc. a real, registered company?
- CoStar Group, Inc. files with the SEC under CIK 1057352 (its SEC filings).
- Its shares are listed under the ticker CSGP on Nasdaq (SEC company record).
- Incorporated in Delaware; business address in Arlington, Virginia, as its SEC filings state.
- Court and bankruptcy records: see Before you sign or pay below.
Before you sign or pay
- Court and bankruptcy: No federal court case or bankruptcy filing found under CoStar Group, Inc. in our court records and SEC 8-K records (as of 2026-11-06).
- Leadership changes: the latest reported is Robin Rossmann, Chief Financial Officer (Form 8-K filed 2026-07-13). Check you are dealing with the people now in charge.
- Ownership: 5%+ holders are reported on Schedule 13D or 13G; the latest names Baron Capital Group, Inc. (filed 2026-08-14).
Who are CoStar Group, Inc.'s owners and officers?
CoStar Group, Inc.: incorporated in Delaware; business address in Arlington, Virginia; industry Services-Business Services, NEC (Schedule 13G, 2026-08-14).
| Report | Holder | Share |
|---|---|---|
| Schedule 13G, 2026-08-14 | Baron Capital Group, Inc. | 5.3% |
| Schedule 13G, 2026-04-29 | Vanguard Capital Management | 7.53% |
| Schedule 13G, 2026-04-29 | Vanguard Portfolio Management | 9.12% |
| Schedule 13G/A, 2026-03-26 | The Vanguard Group | 0% |
Questions about who owns CoStar Group, Inc.
Who owns CoStar Group, Inc.?
On this page, 3 holders' latest ownership filings report 5% or more of CoStar Group, Inc.: Vanguard Portfolio Management (9.12%, Schedule 13G, filed 2026-04-29), Vanguard Capital Management (7.53%, Schedule 13G, filed 2026-04-29) and Baron Capital Group, Inc. (5.3%, Schedule 13G, filed 2026-08-14).
Who are the largest shareholders of CoStar Group, Inc.?
By the share each holder's latest filing reports, the largest holders of CoStar Group, Inc. on this page are Vanguard Portfolio Management (9.12%), Vanguard Capital Management (7.53%) and Baron Capital Group, Inc. (5.3%).
When did Vanguard Portfolio Management buy into CoStar Group, Inc.?
The filings give report dates, not purchase dates. The earliest filing from Vanguard Portfolio Management on this page is the Schedule 13G, filed 2026-04-29, reporting 9.12%.
Is this an audit or a full list?
Neither. The ownership list on this page covers only Schedule 13D and 13G filings, which holders make once they own 5% or more of a class of shares (an amendment can report a stake that has since fallen below 5%); 4 such filings are shown here. It is not an audit and not a full cap table: holders who never reached 5% are not listed, and a stake can change after its latest filing.
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| Filed | Person | Role | Change | Effective |
|---|---|---|---|---|
| Form 8-K, 2026-07-13 | Robin Rossmann | Chief Financial Officer | appointed | 2026-07-31 |
| Form 8-K, 2026-07-13 | Christian Lown | Chief Financial Officer | departed | 2026-07-31 |
| Form 8-K, 2026-07-13 | Christian Lown | departed |
Which insiders own CoStar Group, Inc. shares?
Directors, officers and holders of 10% or more report their shares on Forms 3, 4 and 5. Each line is the latest such report, largest holding first.
- , a director: 1,848,592 shares (0.46% of shares outstanding) (Form 4, 2024-12-12).
- , the chief executive and a founder: 1,806,165.03 shares (0.45% of shares outstanding) (Form 4, 2026-08-05).
- , the chief technology officer: 414,491 shares (0.10% of shares outstanding) (Form 4, 2026-03-17).
- , the president and marketplaces: 278,415 shares (0.07% of shares outstanding) (Form 4, 2026-08-04).
- , a director: 275,715 shares (0.07% of shares outstanding), 229,715 held directly and 46,000 indirectly (Form 4, 2024-12-02).
Shares outstanding: 402,337,328 as of 2026-10-26, from the company's latest SEC cover page.
How much has CoStar Group, Inc. raised?
No fundraising or offering filing from CoStar Group, Inc. is on file with us.
Keep reading
More on CoStar Group, Inc. and the records around it.
CoStar Group, Inc. elsewhere on the record
- Leadership changes Jul 2026
Companies that share a holder
- BAMCO INC /NY/ also filed stake reports on 22 other companies: Birkenstock Holding plc (Aug 2026), Blackstone Digital Infrastructure Trust Inc. (Aug 2026), CAREDX, INC. (Aug 2026)
- Vanguard Portfolio Management also filed stake reports on 941 other companies: Newmark Group Inc (Nov 2026), A10 Networks Inc (Oct 2026), ADT Inc (Oct 2026)
- Vanguard Capital Management also filed stake reports on 1495 other companies: A10 Networks Inc (Oct 2026), Altisource Portfolio Solutions SA (Oct 2026), Alto Neuroscience Inc (Oct 2026)
Related pages
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