Robin Rossmann was named Chief Financial Officer of Costar Group, Inc., succeeding Christian Lown, effective July 31, 2026. As of November 6, 2026, Costar Group, Inc. has reported one leadership change filing to the SEC under Item 5.02 of Form 8-K, on July 13, 2026, naming 1 appointment and 2 departures (Form 8-K, July 13, 2026).
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Key facts
- · In / out: In · Person: Robin Rossmann · Role: Chief Financial Officer · Effective: 2026-07-31 · 8-K, 2026-07-13
- · In / out: Out · Person: Christian Lown · Role: Chief Financial Officer · Effective: 2026-07-31 · 8-K, 2026-07-13
- · In / out: Out · Person: Christian Lown · 8-K, 2026-07-13
Costar Group, Inc. reported a change among its directors and officers to the SEC on Form 8-K, Item 5.02, on 2026-07-13. It names 2 people, with 1 appointment and 2 departures. Every row below is cited to the filing it comes from, and this page adds each new change as Costar Group, Inc. files it.
Also on the record for Costar Group, Inc.
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| August 14, 2026 | Stake report, Schedule 13G, by Baron Capital Group, Inc. | 5.3% of the class | 5%+ stakes | Source |
| April 29, 2026 | Stake report, Schedule 13G, by Vanguard Capital Management | 7.53% of the class | 5%+ stakes | Source |
| April 29, 2026 | Stake report, Schedule 13G, by Vanguard Portfolio Management | 9.12% of the class | 5%+ stakes | Source |
| March 26, 2026 | Stake report, Schedule 13G/A, by The Vanguard Group | — | 5%+ stakes | Source |
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More on Costar Group, Inc. and the records around it.
Costar Group, Inc. elsewhere on the record
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)
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Timeline
| Filed | In / out | Person | Role | Effective | Source |
|---|---|---|---|---|---|
| 2026-07-13 | In | Chief Financial Officer | 2026-07-31 | 8-K, 2026-07-13 | |
| 2026-07-13 | Out | Chief Financial Officer | 2026-07-31 | 8-K, 2026-07-13 | |
| 2026-07-13 | Out | 8-K, 2026-07-13 |
Who leads Costar Group, Inc., as last reported?
For each role that changed in the filings below, the most recent change reported. A role that did not change in these filings is not listed.
- Chief Financial Officer: Robin Rossmann, appointed, effective 2026-07-31 (filed 2026-07-13).
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Find candidates like Chief Financial Officer at Costar Group, Inc.Every change, in the filing's words
Appointed: Robin Rossmann, Chief Financial Officer, effective 2026-07-31
On July 13, 2026, the Board of Directors (the "Board") of CoStar Group, Inc. (the "Company" or "CoStar Group") appointed Robin Rossmann to serve as the Company's Chief Financial Officer, effective July 31, 2026 ("Effective Date").
Departing: Christian Lown, Chief Financial Officer, effective 2026-07-31
On July 7, 2026, Christian Lown, Chief Financial Officer (Principal Financial Officer) of the Company, informed the Company of his decision to resign, effective July 31, 2026, for another opportunity outside the Company's industry.
Departing: Christian Lown
Mr. Lown has advised the Company that his resignation was not a result of any disagreement with the Company on any matter related to the Company's operations, policies or practices.
- Mr. Rossmann, 45, who currently serves as the Company's Managing Director, Europe, and is a member of the Company's executive leadership team, brings more than 20 years of financial, operational and strategic leadership experience to the role of Chief Financial Officer.
- Over his nearly seven years with the Company, Mr. Rossmann has led several of CoStar Group's businesses internationally, distinguished himself by dramatically improving the margins of CoStar Group's European business while delivering double-digit revenue growth and launching CoStar in France.
- Rossmann joined STR in 2016, leading its businesses across EMEA, Asia Pacific and Latin America, and became part of CoStar Group through the Company's acquisition of STR in 2019.
- Over the past decade with STR and CoStar Group, he has played a central role in launching CoStar Group products across global markets, executing and integrating acquisitions, scaling international operations and advancing strategic initiatives that have strengthened the Company's competitive position.
- Prior to joining STR, Rossmann spent 13 years at Deloitte, where he served as a Senior Director advising many of the world's leading public and private real estate and hospitality companies across the United States, the United Kingdom and other international markets.
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Where this comes from
A public company must file a current report on Form 8-K with the SEC within four business days when a director leaves or is elected, or when its chief executive, chief financial, chief accounting or chief operating officer, or another named executive, departs or is appointed. That disclosure goes under Item 5.02 of the report.
Every change on this page is taken from one of those filings and quoted in the company's own words, with a link to the filing, so it can be checked at the source. Where a filing names the person, the role and the date a change takes effect, they are shown beside the quote. Where it does not, the quote stands on its own. A filing states what changed; it rarely states why, and neither does this page.