Over the 90-day window ending January 29, 2026, Costar's three dominant insider ownership positions are held by Director Michael R Klein (1.85Mn shares), President And Ceo Andrew C Florance (1.67Mn shares), Chief Technology Officer Frank Simuro (483.60K shares).
| Holder | Position | Shares | Report Date |
|---|---|---|---|
| Michael R Klein | 1,848,592 | 12 Dec, 2024 | |
| Andrew C Florance | President And Ceo | 1,672,832 | 07 Mar, 2025 |
| Frank Simuro | Chief Technology Officer | 483,599 | 18 Mar, 2025 |
| Scott T Wheeler | Chief Financial Officer | 304,958 | 30 Apr, 2024 |
| Frederick G. Saint | President And Marketplaces | 293,103 | 02 Sep, 2025 |
| Christopher J Nassetta | 275,715 | 02 Dec, 2024 | |
| Lisa Ruggles | Senior Vp And Global Operations | 211,201 | 03 Jun, 2025 |
| Christian M. Lown | Chief Financial Officer | 130,157 | 02 Jul, 2025 |
| Michael J Glosserman | 101,465 | 01 Nov, 2023 | |
| Michael J Desmarais | Chief Human Resources Officer | 79,118 | 18 Mar, 2025 |
| Gene Boxer | General Counsel And Secretary | 78,572 | 18 Mar, 2025 |
| Cynthia Cammett Cann | Chief Accounting Officer | 23,211 | 17 Nov, 2025 |
| Louise S Sams | 19,409 | 11 Sep, 2025 | |
| Robert W Musslewhite | 18,277 | 11 Sep, 2025 | |
| John W Hill | 18,231 | 17 Nov, 2025 | |
| Laura Cox Kaplan | 17,835 | 05 Aug, 2024 | |
| Angelique G. Brunner | 10,166 | 11 Sep, 2025 | |
| Rachel C Glaser | 3,143 | 11 Sep, 2025 | |
| Christine M Mccarthy | 2,973 | 11 Sep, 2025 | |
| John L Berisford | 2,973 | 11 Sep, 2025 |
* Please note that the shares above only reflect shares from the fund portfolio and the institutional portfolio. Shares from the personal portfolio are excluded from this Institutional Ownership Page. See these insiders' latest transactions here on Insider Page.
| Transaction Date | Insider Name | Security Class | Transaction Type | Shares Traded | Price | Shares Remaining | Ownership | Code |
|---|---|---|---|---|---|---|---|---|
| 13 Nov, 2025 | John W Hill | Common Stock, par value $0.01 per share | D | 2,250 | $68.68 | 18,231 | D | S |
| 13 Nov, 2025 | Cynthia Cammett Cann | Common Stock, par value $0.01 per share | D | 1,841 | $68.79 | 23,211 | D | S |
| 09 Sep, 2025 | Christine M Mccarthy | Common Stock, par value $0.01 per share | A | 2,973 | $0.00 | 2,973 | D | A |
| 09 Sep, 2025 | John W Hill | Common Stock, par value $0.01 per share | A | 3,177 | $0.00 | 20,481 | D | A |
| 09 Sep, 2025 | Robert W Musslewhite | Common Stock, par value $0.01 per share | A | 3,121 | $0.00 | 18,277 | D | A |
| 09 Sep, 2025 | John L Berisford | Common Stock, par value $0.01 per share | A | 2,973 | $0.00 | 2,973 | D | A |
| 09 Sep, 2025 | Rachel C Glaser | Common Stock, par value $0.01 per share | A | 3,143 | $0.00 | 3,143 | D | A |
| 09 Sep, 2025 | Angelique G. Brunner | Common Stock, par value $0.01 per share | A | 3,143 | $0.00 | 10,166 | D | A |
| 09 Sep, 2025 | Louise S Sams | - | - | 19,409 | D | |||
| 09 Sep, 2025 | Louise S Sams | Common Stock, par value $0.01 per share | A | 3,291 | $0.00 | 19,409 | D | A |
| 28 Aug, 2025 | Frederick G. Saint | Common Stock, par value $0.01 per share | D | 25,000 | $90.33 | 293,103 | D | S |
| 01 Aug, 2025 | Cynthia Cammett Cann | Common Stock, par value $0.01 per share | D | 719 | $95.19 | 25,052 | D | F |
| 01 Aug, 2025 | Frederick G. Saint | - | - | 318,103 | D | |||
| 01 Aug, 2025 | Frederick G. Saint | Common Stock, par value $0.01 per share | D | 1,436 | $95.19 | 318,103 | D | F |
| 28 Jul, 2025 | Cynthia Cammett Cann | Common Stock, par value $0.01 per share | D | 2,033 | $92.85 | 25,771 | D | S |
| 28 Jul, 2025 | Frederick G. Saint | Common Stock, par value $0.01 per share | D | 25,000 | $93.23 | 319,539 | D | S |
| 01 Jul, 2025 | Christian M. Lown | - | - | 130,157 | D | |||
| 01 Jul, 2025 | Christian M. Lown | Common Stock, par value $0.01 per share | D | 4,666 | $80.40 | 130,157 | D | F |
| 15 Jun, 2025 | Cynthia Cammett Cann | Common Stock, par value $0.01 per share | D | 461 | $81.16 | 27,804 | D | F |
| 11 Jun, 2025 | Frederick G. Saint | Common Stock, par value $0.01 per share | D | 25,000 | $81.10 | 344,539 | D | S |