CoStar Group, Inc. (CSGP) has 20 known insider and institutional holders on record. The largest holder is KLEIN MICHAEL R with 1,848,592 shares. Other notable holders include FLORANCE ANDREW C and SIMURO FRANK.
Over the last 12 months, insiders have made 59 transactions in CSGP stock — 24 buys (valued at $11.84M) and 6 sells (valued at $7.09M). Insider buying has outpaced selling during this period, which may signal confidence in the company's prospects.
CSGP Insider Ownership
Top Holder
KLEIN MICHAEL R
1,848,592 shares
Buys (12 mo)
24
$11.84M value
Sells (12 mo)
6
$7.09M value
12-Month Transaction Activity
Top Insider Holders
| # |
Name |
Role |
Shares Owned |
Last Filed |
Relative Size |
| 1 |
Klein Michael R |
Director |
1,848,592 |
2024-12-12 |
|
| 2 |
Florance Andrew C |
President and CEO |
1,651,435 |
2026-03-11 |
|
| 3 |
Simuro Frank |
Chief Technology Officer |
414,491 |
2026-03-17 |
|
| 4 |
Wheeler Scott T |
Chief Financial Officer |
303,417 |
2024-03-19 |
|
| 5 |
Bonderman David |
Director |
294,277 |
2014-09-15 |
|
| 6 |
Nassetta Christopher J |
Director |
229,715 |
2024-12-02 |
|
| 7 |
Ruggles Lisa |
Senior VP, Global Operations |
174,915 |
2026-03-17 |
|
| 8 |
Lown Christian M. |
Chief Financial Officer |
135,250 |
2026-03-11 |
|
| 9 |
Haber Warren H |
Director |
121,049 |
2018-09-24 |
|
| 10 |
Glosserman Michael J |
Director |
101,465 |
2023-11-01 |
|
| 11 |
Boxer Gene |
General Counsel and Secretary |
95,517 |
2026-03-17 |
|
| 12 |
Desmarais Michael J |
Chief Human Resources Officer |
87,725 |
2026-03-17 |
|
| 13 |
Radecki Brian J |
Chief Financial Officer |
41,473 |
2015-03-13 |
|
| 14 |
Saint Frederick G. |
President, Marketplaces |
39,652 |
2026-03-03 |
|
| 15 |
Marples Paul |
Managing Director, Costar Uk |
28,632 |
2012-08-01 |
|
| 16 |
Cann Cynthia Cammett |
Chief Accounting Officer |
25,148 |
2026-03-17 |
|
| 17 |
Kitchen Jennifer |
Sr. Vice President, Research |
22,220 |
2013-09-11 |
|
| 18 |
Sams Louise S |
Director |
20,409 |
2026-03-09 |
|
| 19 |
Linnington Matthew |
Executive VP, Sales |
19,766 |
2020-08-13 |
|
| 20 |
Musslewhite Robert W |
Director |
18,277 |
2025-09-11 |
|
Recent Transactions (last 12 months)
| Date |
Name |
Role |
Type |
Shares |
Price |
Value |
| 2025-03-25 |
Mccarthy Christine M |
Director |
Unknown |
- |
- |
- |
| 2026-03-15 |
Simuro Frank |
Chief Technology Officer |
Tax Withholding of RSU |
11,107 |
$43.63 |
$484.6K |
| 2026-03-15 |
Desmarais Michael J |
Chief Human Resources Officer |
Tax Withholding of RSU |
2,873 |
$43.63 |
$125.35K |
| 2026-03-15 |
Boxer Gene |
General Counsel and Secretary |
Tax Withholding of RSU |
482 |
$43.63 |
$21.03K |
| 2026-03-15 |
Boxer Gene |
General Counsel and Secretary |
Tax Withholding of RSU |
428 |
$43.63 |
$18.67K |
| 2026-03-15 |
Ruggles Lisa |
Senior VP, Global Operations |
Tax Withholding of RSU |
2,977 |
$43.63 |
$129.89K |
| 2026-03-15 |
Banerjee Nana |
Director |
Unknown |
- |
- |
- |
| 2026-03-15 |
Cann Cynthia Cammett |
Chief Accounting Officer |
Tax Withholding of RSU |
1,194 |
$43.63 |
$52.09K |
| 2026-03-10 |
Desmarais Michael J |
Chief Human Resources Officer |
RSU Award |
17,676 |
$46.34 |
$819.11K |
| 2026-03-10 |
Boxer Gene |
General Counsel and Secretary |
RSU Award |
21,920 |
$46.34 |
$1.02M |
| 2026-03-10 |
Lown Christian M. |
Chief Financial Officer |
RSU Award |
12,268 |
$46.34 |
$568.5K |
| 2026-03-10 |
Cann Cynthia Cammett |
Chief Accounting Officer |
RSU Award |
4,374 |
$46.34 |
$202.69K |
| 2026-03-10 |
Florance Andrew C |
President and CEO |
RSU Award |
124,162 |
$46.34 |
$5.75M |
| 2026-03-06 |
Sams Louise S |
Director |
Informative Buy |
1,000 |
$48.36 |
$48.36K |
| 2026-03-01 |
Simuro Frank |
Chief Technology Officer |
Tax Withholding of RSU |
18,702 |
$44.63 |
$834.67K |
| 2026-02-27 |
Simuro Frank |
Chief Technology Officer |
RSU Award |
52,869 |
- |
- |
| 2026-03-01 |
Desmarais Michael J |
Chief Human Resources Officer |
Tax Withholding of RSU |
6,353 |
$44.63 |
$283.53K |
| 2026-02-27 |
Desmarais Michael J |
Chief Human Resources Officer |
RSU Award |
17,926 |
- |
- |
| 2026-03-01 |
Boxer Gene |
General Counsel and Secretary |
Tax Withholding of RSU |
4,547 |
$44.63 |
$202.93K |
| 2026-02-27 |
Boxer Gene |
General Counsel and Secretary |
RSU Award |
26,888 |
- |
- |
| 2026-03-01 |
Ruggles Lisa |
Senior VP, Global Operations |
Tax Withholding of RSU |
8,931 |
$44.63 |
$398.59K |
| 2026-02-27 |
Ruggles Lisa |
Senior VP, Global Operations |
RSU Award |
28,197 |
- |
- |
| 2026-03-01 |
Lown Christian M. |
Chief Financial Officer |
Tax Withholding of RSU |
7,175 |
$44.63 |
$320.22K |
| 2026-02-27 |
Lown Christian M. |
Chief Financial Officer |
RSU Award |
39,652 |
- |
- |
| 2026-03-02 |
Saint Frederick G. |
President, Marketplaces |
Informative Buy |
20,000 |
$45.33 |
$906.6K |
