CoStar Group, Inc. (CSGP) ownership: Top institutional holder: VANGUARD GROUP INC ($4.71B). Insider activity: Net Seller (5 buys, 15 sells). 10 recent congressional STOCK Act disclosures. SEC EDGAR first-party data.
| Holder | Shares | Market Value | Reported |
|---|---|---|---|
| VANGUARD GROUP INC | 70108999.00 | $4.71B | 2025-12-31 |
| VANGUARD PORTFOLIO MANAGEMENT LLC | 38234133.00 | $1.54B | 2026-03-31 |
| BlackRock, Inc. | 33808184.00 | $1.36B | 2026-03-31 |
| VANGUARD CAPITAL MANAGEMENT LLC | 27423903.00 | $1.11B | 2026-03-31 |
| STATE STREET CORP | 18650975.00 | $752.38M | 2026-03-31 |
| PRINCIPAL FINANCIAL GROUP INC | 17696192.00 | $713.87M | 2026-03-31 |
| BAMCO INC /NY/ | 16314175.00 | $658.11M | 2026-03-31 |
| Capital International Investors | 15513753.00 | $625.82M | 2026-03-31 |
| Insider | Transaction | Value | Date |
|---|---|---|---|
| Sell | null | 2026-06-15 | |
| Buy | null | 2026-05-01 | |
| Buy | null | 2026-05-01 | |
| Sell | null | 2026-03-15 | |
| Sell | null | 2026-03-15 | |
| Sell | null | 2026-03-15 | |
| Sell | null | 2026-03-15 | |
| Sell | null | 2026-03-15 |
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Institutional data from SEC Form 13F. Insider data from SEC Form 4. Congressional data from STOCK Act disclosures. Not personalized investment advice.