CSGP · Insider Trading
CoStar Group Inc
Every open-market purchase and sale reported by CSGP officers, directors and 10%+ beneficial owners on SEC Form 4, which must be filed within two business days of the transaction. Sales often reflect scheduled 10b5-1 plans or tax withholding rather than a directional view, so read counts alongside the size and the filer.
| Filed | Insider | Role | Type | Shares | Value |
|---|---|---|---|---|---|
| 2026-10-16 | Robin Jack Rossmann | Chief Financial Officer | F | −756 | −$24.19K |
| 2026-08-10 | Cynthia Cammett Cann | Chief Accounting Officer | Sell | −4,788 | −$147.37K |
| 2026-08-10 | John W Hill | Director | Sell | −3,500 | −$105.73K |
| 2026-08-05 | Andrew C Florance | Founder and CEO | Buy | +83,300 | +$2.49M |
| 2026-08-04 | Robin Jack Rossmann | Chief Financial Officer | A | +34,771 deriv. | — |
| 2026-08-04 | G. Saint Frederick | President, Marketplaces | F | −1,436 | −$41.30K |
| 2026-08-04 | Cynthia Cammett Cann | Chief Accounting Officer | F | −1,077 | −$30.97K |
| 2026-07-06 | Christian M. Lown | Chief Financial Officer | F | −5,597 | −$164.33K |
| 2026-06-24 | Christine M McCarthy | Director | A | +8,262 | — |
| 2026-06-24 | Louise S Sams | Director | A | +8,262 | — |
| 2026-06-24 | Robert W Musslewhite | Director | A | +8,262 | — |
| 2026-06-24 | John L Berisford | Director | A | +8,262 | — |
| 2026-06-24 | Angelique G. Brunner | Director | A | +8,262 | — |
| 2026-06-24 | John W Hill | Director | A | +8,262 | — |
| 2026-06-24 | Rachel C Glaser | Director | A | +8,262 | — |
| 2026-06-16 | Cynthia Cammett Cann | Chief Accounting Officer | F | −461 | −$14.77K |
| 2026-05-04 | Andrew C Florance | President and CEO | Buy | +71,430 | +$2.51M |
| 2026-03-17 | Gene Boxer | General Counsel and Secretary | F | −482 | −$21.03K |
| 2026-03-17 | Cynthia Cammett Cann | Chief Accounting Officer | F | −1,194 | −$52.09K |
| 2026-03-17 | Michael J Desmarais | Chief Human Resources Officer | F | −2,873 | −$125.35K |
| 2026-03-17 | Frank Simuro | Chief Technology Officer | F | −11,107 | −$484.60K |
| 2026-03-17 | Gene Boxer | General Counsel and Secretary | F | −428 | −$18.67K |
| 2026-03-17 | Lisa Ruggles | Senior VP, Global Operations | F | −2,977 | −$129.89K |
| 2026-03-11 | Michael J Desmarais | Chief Human Resources Officer | A | +17,676 | — |
| 2026-03-11 | Gene Boxer | General Counsel and Secretary | A | +21,920 | — |
| 2026-03-11 | Christian M. Lown | Chief Financial Officer | A | +12,268 | — |
| 2026-03-11 | Andrew C Florance | President and CEO | A | +124,162 | — |
| 2026-03-11 | Cynthia Cammett Cann | Chief Accounting Officer | A | +4,374 | — |
| 2026-03-09 | Louise S Sams | Director | Buy | +1,000 | +$48.36K |
| 2026-03-03 | G. Saint Frederick | President, Marketplaces | MIXED | +8,904 | +$411.39K |
| 2026-03-03 | Rachel C Glaser | Director | Buy | +1,000 | +$44.94K |
| 2026-03-03 | Frank Simuro | Chief Technology Officer | F | −18,702 | −$834.67K |
| 2026-03-03 | Lisa Ruggles | Senior VP, Global Operations | F | −8,931 | −$398.59K |
| 2026-03-03 | Cynthia Cammett Cann | Chief Accounting Officer | F | −1,385 | −$61.81K |
| 2026-03-03 | Michael J Desmarais | Chief Human Resources Officer | F | −6,353 | −$283.53K |
| 2026-03-03 | Gene Boxer | General Counsel and Secretary | F | −4,547 | −$202.93K |
| 2026-03-03 | Andrew C Florance | President and CEO | F | −59,593 | −$2.66M |
| 2026-03-03 | G. Saint Frederick | President, Marketplaces | A | +39,652 deriv. | — |
| 2026-03-03 | Christian M. Lown | Chief Financial Officer | F | −7,175 | −$320.22K |
| 2026-03-02 | Andrew C Florance | President and CEO | Buy | +55,720 | +$2.48M |
| 2026-02-23 | Lisa Ruggles | Senior VP, Global Operations | MIXED | −20,802 | −$157.96K |
| 2026-02-23 | Andrew C Florance | President and CEO | MIXED | −124,204 | −$943.17K |
| 2026-02-23 | G. Saint Frederick | President, Marketplaces | MIXED | −19,732 | −$105.45K |
| 2026-02-23 | Frank Simuro | Chief Technology Officer | MIXED | −35,148 | −$216.94K |
| 2026-02-18 | G. Saint Frederick | President, Marketplaces | F | −2,424 | −$109.06K |
| 2026-02-18 | Lisa Ruggles | Senior VP, Global Operations | F | −3,576 | −$160.88K |
| 2026-02-18 | Andrew C Florance | President and CEO | F | −17,482 | −$786.52K |
| 2026-02-18 | Frank Simuro | Chief Technology Officer | F | −4,151 | −$186.75K |
| 2025-11-17 | Cynthia Cammett Cann | Chief Accounting Officer | Sell | −1,841 | −$126.64K |
| 2025-11-17 | John W Hill | Director | Sell | −2,250 | −$154.53K |
| Insider | Role | Shares Held | Value |
|---|---|---|---|
| Michael R Klein | Director | 1,848,592 | $57.64M |
| Andrew C Florance | Founder and CEO | 1,806,165 | $56.32M |
| Frank Simuro | Chief Technology Officer | 414,491 | $12.92M |
| G. Saint Frederick | President, Marketplaces | 278,415 | $8.68M |
| Christopher J Nassetta | Director | 275,715 | $8.60M |
| Lisa Ruggles | Senior VP, Global Operations | 174,915 | $5.45M |
| Christian M. Lown | Chief Financial Officer | 129,653 | $4.04M |
| Gene Boxer | General Counsel and Secretary | 95,517 | $2.98M |
| Michael J Desmarais | Chief Human Resources Officer | 87,725 | $2.74M |
| Robin Jack Rossmann | Chief Financial Officer | 85,935 | $2.68M |
| Louise S Sams | Director | 28,671 | $893.96K |
| Robert W Musslewhite | Director | 26,539 | $827.49K |
| John W Hill | Director | 22,993 | $716.92K |
| Cynthia Cammett Cann | Chief Accounting Officer | 18,822 | $586.87K |
| Angelique G. Brunner | Director | 18,428 | $574.59K |
| Rachel C Glaser | Director | 12,419 | $387.22K |
| Christine M McCarthy | Director | 11,585 | $361.22K |
| John L Berisford | Director | 11,235 | $350.31K |
Form 4 reports a change in beneficial ownership by an officer, director or 10%+ holder, and must be filed within two business days of the transaction — so this is close to real time, unlike the 45-day-lagged 13F institutional data.
Transaction codes matter more than the raw buy/sell count. Code P is an open-market purchase — an insider choosing to buy with their own money, which is the signal most research treats as informative. Code S is a sale, but sales are frequently pre-scheduled under a 10b5-1 plan or cover tax withholding on vesting equity, so a run of sales often says nothing directional. Codes A and M are grants and option exercises rather than open-market decisions.
Full filing history and per-insider positions are on the CSGP quote page; the site-wide leaderboard is on the insider transactions hub.
Market data may be delayed, incomplete, or inaccurate. Not a recommendation to buy, sell, or hold any security. Verify quotes with your broker before trading. See Terms §17.