CoStar Group, Inc. (CSGP) Shareholders & Insider Trades
CoStar shareholders at a glance
The largest holder of CoStar stock is Vanguard Portfolio Management LLC, with 37.9 million shares (9.36% of the company), worth about $1.22 billion as of September 25, 2026. The 10 largest holders together own 48.0%.
In Q2 2026, 802 institutional holdings reports listed shares worth $13.00 billion.
Insiders reported 44 transactions in the last two years: 11 sales worth $13.56 million and 6 purchases. The newest one on file is from May 1, 2026 (Florance Andrew Colden, Chief Executive Officer).
Major holders as of September 25, 2026; quarterly totals from institutional holdings reports (latest Q2 2026); insider transactions on file through May 1, 2026.
CoStar Group, Inc.
Shareholders Summary
2026Q2
Ownership by Type
Geographic Distribution
Largest CoStar shareholders
| Holder | Shares | % of company | Value |
|---|---|---|---|
| Vanguard Portfolio Management LLC | 37.9 million | 9.36% | $1.2B |
| BlackRock Advisors LLC | 27.5 million | 6.78% | $881.0M |
| Vanguard Capital Management LLC | 26.7 million | 6.58% | $856.0M |
| BAMCO, Inc. | 21.6 million | 5.34% | $694.0M |
| State Street Corporation | 18.4 million | 4.54% | $590.0M |
| Capital Research & Management Co. (International Investors) | 16.6 million | 4.11% | $534.0M |
| Baillie Gifford & Co. | 13.2 million | 3.25% | $422.0M |
| Geode Capital Management LLC | 12.2 million | 3.00% | $390.0M |
| Akre Capital Management LLC | 11.7 million | 2.89% | $375.0M |
| Polen Capital Management LLC | 8.8 million | 2.16% | $281.0M |
As of September 25, 2026.
CoStar institutional holdings by quarter
| Quarter | Reports | Shares | Value |
|---|---|---|---|
| Q2 2026 | 802 | – | $13.0B |
| Q1 2026 | 837 | 416.0 million | $16.8B |
| Q4 2025 | 900 | – | $28.6B |
| Q3 2025 | 960 | 417.0 million | $35.1B |
| Q2 2025 | 921 | 427.0 million | $34.4B |
| Q1 2025 | 904 | 430.0 million | $34.1B |
| Q4 2024 | 846 | 410.0 million | $29.3B |
| Q3 2024 | 815 | 401.0 million | $30.2B |
Shares and value held by institutions that file quarterly holdings reports (options not included).
CoStar insider trades
| Insider | Date | Title | Transaction | Value |
|---|---|---|---|---|
| Florance Andrew Colden | May 1, 2026 | Chief Executive Officer | Purchase at price 35.17 - 35.82 per share. | $2.5M |
| Cann Cynthia Cammett | Mar 10, 2026 | Officer | Stock Award(Grant) at price 0.00 per share. | – |
| Lown Christian M | Mar 10, 2026 | Chief Financial Officer | Stock Award(Grant) at price 0.00 per share. | – |
| Florance Andrew Colden | Mar 10, 2026 | Chief Executive Officer | Stock Award(Grant) at price 0.00 per share. | – |
| Boxer Gene | Mar 10, 2026 | General Counsel | Stock Award(Grant) at price 0.00 per share. | – |
| Desmarais Michael J | Mar 10, 2026 | Officer | Stock Award(Grant) at price 0.00 per share. | – |
| Sams Louise S. | Mar 6, 2026 | Director | Purchase at price 48.36 per share. | $48,360 |
| Glaser Rachel C | Mar 2, 2026 | Director | Purchase at price 44.94 per share. | $44,940 |
| Saint Frederick G | Mar 2, 2026 | Officer | Purchase at price 45.33 per share. | $906,600 |
| Florance Andrew Colden | Feb 27, 2026 | Chief Executive Officer | Purchase at price 44.52 per share. | $2.5M |
| Hill John W | Nov 13, 2025 | Director | Sale at price 68.68 per share. | $154,530 |
| Cann Cynthia Cammett | Nov 13, 2025 | Officer | Sale at price 68.79 per share. | $126,642 |
Newest 12 of 44 insider transactions in the last two years.
Questions and answers
Who owns the most CoStar stock?
Vanguard Portfolio Management LLC, with 9.36% of the company (as of September 25, 2026). Next: BlackRock Advisors LLC (6.78%) and Vanguard Capital Management LLC (6.58%).
How many institutions own CoStar stock?
802 institutional holdings reports listed CoStar shares in Q2 2026 worth $13.00 billion.
Are CoStar insiders buying or selling the stock?
In the last two years insiders reported 11 sales and 6 purchases (44 transactions in all); the newest on file is from May 1, 2026.
