CoStar insider activity
What the executives and directors of CoStar actually did with their own shares, decoded from their SEC Form 4 filings. Each figure says the stretch of time it covers.
$8.0M
net open-market flow, 12 m
7 open-market buys, 12 m
0%
of sale value on 10b5-1 plans, 12 m
48 days since an insider bought, whole record
The tape: three years of insider trades
Open-market buy
Discretionary sale
Planned sale (10b5-1)
Reported-price path
Routine
Every marker sits at the price reported on the Form 4. The line is the monthly median of all prices insiders reported, so the chart needs no market feed; the grey strip is the routine flow (grants, vestings, tax withholding and gifts) that a headline gets wrong by counting it as selling.
The 122 routine events on the chart, as a list
| Date | Insider | Shares |
|---|---|---|
| Aug 1, 2026 | Cann Cynthia Cammett | 1,077 |
| Aug 1, 2026 | SAINT FREDERICK G. | 1,436 |
| Jul 1, 2026 | LOWN CHRISTIAN M. | 5,597 |
| Jun 23, 2026 | McCarthy Christine M | 8,262 |
| Jun 23, 2026 | Hill John W | 8,262 |
| Jun 23, 2026 | Musslewhite Robert W | 8,262 |
| Jun 23, 2026 | BERISFORD JOHN L | 8,262 |
| Jun 23, 2026 | Glaser Rachel C | 8,262 |
| Jun 23, 2026 | Brunner Angelique G. | 8,262 |
| Jun 23, 2026 | Sams Louise S | 8,262 |
| Jun 15, 2026 | Cann Cynthia Cammett | 461 |
| Mar 15, 2026 | Cann Cynthia Cammett | 5,568 |
| Mar 15, 2026 | Boxer Gene | 23K |
| Mar 15, 2026 | DESMARAIS MICHAEL J | 21K |
| Mar 15, 2026 | Ruggles Lisa | 2,977 |
| Mar 15, 2026 | SIMURO FRANK | 11K |
| Mar 10, 2026 | FLORANCE ANDREW C | 124K |
| Mar 10, 2026 | LOWN CHRISTIAN M. | 12K |
| Mar 1, 2026 | FLORANCE ANDREW C | 60K |
| Mar 1, 2026 | Cann Cynthia Cammett | 1,385 |
| Mar 1, 2026 | SAINT FREDERICK G. | 11K |
| Mar 1, 2026 | LOWN CHRISTIAN M. | 7,175 |
| Mar 1, 2026 | Ruggles Lisa | 8,931 |
| Mar 1, 2026 | Boxer Gene | 4,547 |
| Mar 1, 2026 | DESMARAIS MICHAEL J | 6,353 |
| Mar 1, 2026 | SIMURO FRANK | 19K |
| Feb 19, 2026 | FLORANCE ANDREW C | 19K |
| Feb 19, 2026 | SAINT FREDERICK G. | 2,149 |
| Feb 19, 2026 | Ruggles Lisa | 3,219 |
| Feb 19, 2026 | SIMURO FRANK | 4,421 |
| Feb 15, 2026 | FLORANCE ANDREW C | 17K |
| Feb 15, 2026 | SAINT FREDERICK G. | 2,424 |
| Feb 15, 2026 | Ruggles Lisa | 3,576 |
| Feb 15, 2026 | SIMURO FRANK | 4,151 |
| Sep 9, 2025 | McCarthy Christine M | 2,973 |
| Sep 9, 2025 | Hill John W | 3,177 |
| Sep 9, 2025 | Musslewhite Robert W | 3,121 |
| Sep 9, 2025 | BERISFORD JOHN L | 2,973 |
| Sep 9, 2025 | Glaser Rachel C | 3,143 |
| Sep 9, 2025 | Brunner Angelique G. | 3,143 |
| Sep 9, 2025 | Sams Louise S | 3,291 |
| Aug 1, 2025 | Cann Cynthia Cammett | 719 |
| Aug 1, 2025 | SAINT FREDERICK G. | 1,436 |
| Jul 1, 2025 | LOWN CHRISTIAN M. | 4,666 |
| Jun 15, 2025 | Cann Cynthia Cammett | 461 |
| Jun 1, 2025 | Ruggles Lisa | 12 |
| Mar 15, 2025 | Cann Cynthia Cammett | 1,191 |
| Mar 15, 2025 | Ruggles Lisa | 1,958 |
| Mar 15, 2025 | Boxer Gene | 481 |
| Mar 15, 2025 | DESMARAIS MICHAEL J | 3,641 |
| Mar 15, 2025 | SIMURO FRANK | 5,700 |
| Mar 5, 2025 | FLORANCE ANDREW C | 76K |
| Mar 5, 2025 | Cann Cynthia Cammett | 1,498 |
| Mar 5, 2025 | Boxer Gene | 12K |
| Mar 5, 2025 | DESMARAIS MICHAEL J | 9,026 |
| Mar 1, 2025 | Cann Cynthia Cammett | 4,848 |
| Mar 1, 2025 | Boxer Gene | 31K |
| Mar 1, 2025 | DESMARAIS MICHAEL J | 23K |
| Mar 1, 2025 | FLORANCE ANDREW C | 41K |
| Mar 1, 2025 | SAINT FREDERICK G. | 8,252 |
Where the shares went, last 12 months
Every Form 4 movement decomposed: what flowed in (grants, vested equity, purchases) and what flowed out (tax withholding, plan sales, discretionary sales, gifts). Counted in shares, because grants carry no price.
The chart, in numbers
| Flow | Shares |
|---|---|
| Granted | 238K |
| Bought on market | 232K |
| Withheld for tax | 373K |
| Discretionary sales | 12K |
| Kept | 85K |
Skin in the game
Directly held shares as reported after each trade, indexed to 100 at the start of the window, up to five years back. Direct holdings only: trust and family-entity positions are per-entity in the filings and do not sum honestly, so this chart refuses to guess. The steps are the trades.
The chart, in numbers
| Insider | Start of the window | Latest reported | Indexed, start = 100 |
|---|---|---|---|
| KLEIN MICHAEL R | 2.2M | 1.8M | 83.1 |
| FLORANCE ANDREW C | 680K | 1.8M | 265.5 |
| SIMURO FRANK | 346K | 414K | 119.8 |
| SAINT FREDERICK G. | 236K | 278K | 118.1 |
| NASSETTA CHRISTOPHER J | 269K | 230K | 85.3 |
Who holds what
the 14 largest holdings of 20| Insider | Role | Shares held | Buys 12 m | Sales 12 m | 12 m | Last trade |
|---|---|---|---|---|---|---|
| KLEIN MICHAEL R Last trade Oct 25, 2024 | Director | 1.8M | – | – | Oct 25, 2024 | |
| FLORANCE ANDREW C Founder and CEO Last trade Aug 4, 2026 | CEO | 1.8M | $7.5M | – | net buying over the year: 3 months buying, 0 months selling | Aug 4, 2026 |
| SIMURO FRANK Chief Technology Officer Last trade Jun 27, 2023 | Officer | 414K | – | – | Jun 27, 2023 | |
| Wheeler Scott T Chief Financial Officer Last trade Apr 26, 2024 | CFO | 348K | – | – | Apr 26, 2024 | |
| SAINT FREDERICK G. President, Marketplaces Last trade Mar 2, 2026 | Officer | 278K | $907K | – | net buying over the year: 1 month buying, 0 months selling | Mar 2, 2026 |
| NASSETTA CHRISTOPHER J Last trade Nov 27, 2024 | Director | 276K | – | – | Nov 27, 2024 | |
| Ruggles Lisa Senior VP, Global Operations Last trade May 9, 2024 | Officer | 175K | – | – | May 9, 2024 | |
| LOWN CHRISTIAN M. Chief Financial Officer | CFO | 130K | – | – | – | |
| Glosserman Michael J Last trade Aug 1, 2016 | Director | 101K | – | – | Aug 1, 2016 | |
| Boxer Gene General Counsel and Secretary | Officer | 95K | – | – | – | |
| DESMARAIS MICHAEL J Chief Human Resources Officer Last trade Nov 26, 2024 | Officer | 88K | – | – | Nov 26, 2024 | |
| Sams Louise S Last trade Mar 6, 2026 | Director | 29K | $48K | – | net buying over the year: 1 month buying, 0 months selling | Mar 6, 2026 |
| Musslewhite Robert W | Director | 27K | – | – | – | |
| Hill John W Last trade Aug 5, 2026 | Director | 23K | – | $260K | net selling over the year: 0 months buying, 2 months selling | Aug 5, 2026 |
Open-market trade log
the 60 most recent of 212| Date | Insider | Type | Shares | Price | Value | Since trade | Filed |
|---|---|---|---|---|---|---|---|
| Aug 7, 2026 | Cann Cynthia Cammett (Officer) 4,788 shares $30.78 −1.9% since trade filed Aug 10, 2026 | Discretionary sale | 4,788 | $30.78 | $147K | −1.9% | Aug 10, 2026 |
| Aug 5, 2026 | Hill John W (Director) 3,500 shares $30.21 +0.0% since trade filed Aug 10, 2026 | Discretionary sale | 3,500 | $30.21 | $106K | +0.0% | Aug 10, 2026 |
| Aug 4, 2026 | FLORANCE ANDREW C (CEO) 83K shares $29.89 +1.1% since trade filed Aug 5, 2026 | Open-market buy | 83K | $29.89 | $2.5M | +1.1% | Aug 5, 2026 |
| May 1, 2026 | FLORANCE ANDREW C (CEO) 3,100 shares $35.82 −15.7% since trade filed May 4, 2026 | Open-market buy | 3,100 | $35.82 | $111K | −15.7% | May 4, 2026 |
| May 1, 2026 | FLORANCE ANDREW C (CEO) 68K shares $35.17 −14.1% since trade filed May 4, 2026 | Open-market buy | 68K | $35.17 | $2.4M | −14.1% | May 4, 2026 |
| Mar 6, 2026 | Sams Louise S (Director) 1,000 shares $48.36 −37.5% since trade filed Mar 9, 2026 | Open-market buy | 1,000 | $48.36 | $48K | −37.5% | Mar 9, 2026 |
| Mar 2, 2026 | Glaser Rachel C (Director) 1,000 shares $44.94 −32.8% since trade filed Mar 3, 2026 | Open-market buy | 1,000 | $44.94 | $45K | −32.8% | Mar 3, 2026 |
| Mar 2, 2026 | SAINT FREDERICK G. (Officer) 20K shares $45.33 −33.4% since trade filed Mar 3, 2026 | Open-market buy | 20K | $45.33 | $907K | −33.4% | Mar 3, 2026 |
| Feb 27, 2026 | FLORANCE ANDREW C (CEO) 56K shares $44.52 −32.1% since trade filed Mar 2, 2026 | Open-market buy | 56K | $44.52 | $2.5M | −32.1% | Mar 2, 2026 |
| Nov 13, 2025 | Hill John W (Director) 2,250 shares $68.68 −56.0% since trade filed Nov 17, 2025 | Discretionary sale | 2,250 | $68.68 | $155K | −56.0% | Nov 17, 2025 |
| Nov 13, 2025 | Cann Cynthia Cammett (Officer) 1,841 shares $68.79 −56.1% since trade filed Nov 17, 2025 | Discretionary sale | 1,841 | $68.79 | $127K | −56.1% | Nov 17, 2025 |
| Aug 28, 2025 | SAINT FREDERICK G. (Officer) 25K shares $90.33 −66.6% since trade filed Sep 2, 2025 | Discretionary sale | 25K | $90.33 | $2.3M | −66.6% | Sep 2, 2025 |
| Jul 28, 2025 | Cann Cynthia Cammett (Officer) 2,033 shares $92.85 −67.5% since trade filed Jul 29, 2025 | Discretionary sale | 2,033 | $92.85 | $189K | −67.5% | Jul 29, 2025 |
| Jul 28, 2025 | SAINT FREDERICK G. (Officer) 25K shares $93.23 −67.6% since trade filed Jul 29, 2025 | Discretionary sale | 25K | $93.23 | $2.3M | −67.6% | Jul 29, 2025 |
| Jun 11, 2025 | SAINT FREDERICK G. (Officer) 25K shares $81.10 −62.8% since trade filed Jun 12, 2025 | Discretionary sale | 25K | $81.10 | $2.0M | −62.8% | Jun 12, 2025 |
| Mar 10, 2025 | Cann Cynthia Cammett (Officer) 1,749 shares $79.90 −62.2% since trade filed Mar 14, 2025 late | Discretionary sale | 1,749 | $79.90 | $140K | −62.2% | Mar 14, 2025 late |
| Dec 10, 2024 | Hill John W (Director) 2,735 shares $76.76 −60.6% since trade filed Dec 12, 2024 | Discretionary sale | 2,735 | $76.76 | $210K | −60.6% | Dec 12, 2024 |
| Nov 27, 2024 | NASSETTA CHRISTOPHER J (Director) 1,681 shares $80.39 −62.4% since trade filed Dec 2, 2024 | Discretionary sale | 1,681 | $80.39 | $135K | −62.4% | Dec 2, 2024 |
| Nov 26, 2024 | DESMARAIS MICHAEL J (Officer) 5,500 shares $79.88 −62.2% since trade filed Nov 27, 2024 | Discretionary sale | 5,500 | $79.88 | $439K | −62.2% | Nov 27, 2024 |
| Nov 11, 2024 | Cann Cynthia Cammett (Officer) 1,310 shares $76.85 −60.7% since trade filed Mar 14, 2025 late | Discretionary sale | 1,310 | $76.85 | $101K | −60.7% | Mar 14, 2025 late |
| Oct 25, 2024 | FLORANCE ANDREW C (CEO) 15K shares $74.67 −59.5% since trade filed Oct 28, 2024 | Open-market buy | 15K | $74.67 | $1.1M | −59.5% | Oct 28, 2024 |
| Oct 25, 2024 | KLEIN MICHAEL R (Director) 72K shares $74.69 −59.6% since trade filed Oct 28, 2024 | Discretionary sale | 72K | $74.69 | $5.4M | −59.6% | Oct 28, 2024 |
| Jul 31, 2024 | Cann Cynthia Cammett (Officer) 1,200 shares $78.20 −61.4% since trade filed Mar 14, 2025 late | Discretionary sale | 1,200 | $78.20 | $94K | −61.4% | Mar 14, 2025 late |
| Jul 30, 2024 | Hill John W (Director) 1,325 shares $78.16 −61.4% since trade filed Aug 1, 2024 | Discretionary sale | 1,325 | $78.16 | $104K | −61.4% | Aug 1, 2024 |
| May 16, 2024 | SAINT FREDERICK G. (Officer) 2,500 shares $88.43 −65.8% since trade filed May 17, 2024 | Discretionary sale | 2,500 | $88.43 | $221K | −65.8% | May 17, 2024 |
| May 9, 2024 | Ruggles Lisa (Officer) 20K shares $91.15 −66.9% since trade filed May 10, 2024 | Discretionary sale | 20K | $91.15 | $1.8M | −66.9% | May 10, 2024 |
| Apr 26, 2024 | Wheeler Scott T (CFO) 123K shares $92.61 −67.4% since trade filed Apr 30, 2024 | Discretionary sale | 123K | $92.61 | $11M | −67.4% | Apr 30, 2024 |
| Apr 26, 2024 | DESMARAIS MICHAEL J (Officer) 3,800 shares $92.67 −67.4% since trade filed Apr 30, 2024 | Discretionary sale | 3,800 | $92.67 | $352K | −67.4% | Apr 30, 2024 |
| Nov 28, 2023 | Hill John W (Director) 3,020 shares $84.07 −64.1% since trade filed Nov 29, 2023 | Discretionary sale | 3,020 | $84.07 | $254K | −64.1% | Nov 29, 2023 |
| Nov 8, 2023 | NASSETTA CHRISTOPHER J (Director) 1,500 shares $77.86 −61.2% since trade filed Nov 9, 2023 | Discretionary sale | 1,500 | $77.86 | $117K | −61.2% | Nov 9, 2023 |
| Jun 30, 2023 | Ruggles Lisa (Officer) 30K shares $91.42 −67.0% since trade filed Jun 30, 2023 | Discretionary sale | 30K | $91.42 | $2.8M | −67.0% | Jun 30, 2023 |
| Jun 28, 2023 | Wheeler Scott T (CFO) 22K shares $89.30 −66.2% since trade filed Jun 30, 2023 | Discretionary sale | 22K | $89.30 | $1.9M | −66.2% | Jun 30, 2023 |
| Jun 27, 2023 | SIMURO FRANK (Officer) 92K shares $89.65 −66.3% since trade filed Jun 28, 2023 | Discretionary sale | 92K | $89.65 | $8.3M | −66.3% | Jun 28, 2023 |
| Jun 26, 2023 | Hill John W (Director) 1,500 shares $86.57 −65.1% since trade filed Jun 28, 2023 | Discretionary sale | 1,500 | $86.57 | $130K | −65.1% | Jun 28, 2023 |
| Jun 12, 2023 | Wheeler Scott T (CFO) 25K shares $80.68 −62.6% since trade filed Jun 14, 2023 | Discretionary sale | 25K | $80.68 | $2.0M | −62.6% | Jun 14, 2023 |
| Jun 7, 2023 | SAINT FREDERICK G. (Officer) 30K shares $80.24 −62.4% since trade filed Jun 9, 2023 | Discretionary sale | 30K | $80.24 | $2.4M | −62.4% | Jun 9, 2023 |
| Apr 28, 2023 | FLORANCE ANDREW C (CEO) 361K shares $76.77 −60.7% since trade filed May 2, 2023 | Discretionary sale | 361K | $76.77 | $28M | −60.7% | May 2, 2023 |
| Mar 31, 2023 | Hill John W (Director) 2,300 shares $68.50 −55.9% since trade filed Apr 4, 2023 | Discretionary sale | 2,300 | $68.50 | $158K | −55.9% | Apr 4, 2023 |
| Mar 8, 2023 | DESMARAIS MICHAEL J (Officer) 5,600 shares $70.36 −57.1% since trade filed Mar 9, 2023 | Discretionary sale | 5,600 | $70.36 | $394K | −57.1% | Mar 9, 2023 |
| Mar 1, 2023 | SIMURO FRANK (Officer) 35K shares $70.09 −56.9% since trade filed Mar 3, 2023 | Discretionary sale | 35K | $70.09 | $2.5M | −56.9% | Mar 3, 2023 |
| Nov 3, 2022 | Hill John W (Director) 3,650 shares $78.92 −61.7% since trade filed Nov 4, 2022 | Discretionary sale | 3,650 | $78.92 | $288K | −61.7% | Nov 4, 2022 |
| Oct 28, 2022 | DESMARAIS MICHAEL J (Officer) 1,296 shares $82.81 −63.5% since trade filed Oct 31, 2022 | Discretionary sale | 1,296 | $82.81 | $107K | −63.5% | Oct 31, 2022 |
| Aug 10, 2022 | Hill John W (Director) 1,400 shares $74.49 −59.4% since trade filed Aug 11, 2022 | Discretionary sale | 1,400 | $74.49 | $104K | −59.4% | Aug 11, 2022 |
| Aug 5, 2022 | KLEIN MICHAEL R (Director) 150K shares $72.42 −58.3% since trade filed Aug 9, 2022 | Discretionary sale | 150K | $72.42 | $11M | −58.3% | Aug 9, 2022 |
| Aug 3, 2022 | DESMARAIS MICHAEL J (Officer) 2,000 shares $72.51 −58.3% since trade filed Aug 5, 2022 | Discretionary sale | 2,000 | $72.51 | $145K | −58.3% | Aug 5, 2022 |
| May 24, 2022 | Hill John W (Director) 1,750 shares $57.07 −47.1% since trade filed May 26, 2022 | Discretionary sale | 1,750 | $57.07 | $100K | −47.1% | May 26, 2022 |
| May 2, 2022 | DESMARAIS MICHAEL J (Officer) 1,000 shares $63.14 −52.2% since trade filed May 4, 2022 | Discretionary sale | 1,000 | $63.14 | $63K | −52.2% | May 4, 2022 |
| Mar 2, 2022 | Ruggles Lisa (Officer) 22K shares $59.88 −49.6% since trade filed Mar 3, 2022 | Discretionary sale | 22K | $59.88 | $1.3M | −49.6% | Mar 3, 2022 |
| Nov 11, 2021 | Wheeler Scott T (CFO) 85 shares $81.72 −63.0% since trade filed Nov 15, 2021 | Discretionary sale | 85 | $81.72 | $7K | −63.0% | Nov 15, 2021 |
| Nov 10, 2021 | NASSETTA CHRISTOPHER J (Director) 2,120 shares $83.21 −63.7% since trade filed Nov 12, 2021 | Discretionary sale | 2,120 | $83.21 | $176K | −63.7% | Nov 12, 2021 |
| Nov 5, 2021 | Kaplan Laura Cox (Director) 4,040 shares $83.29 −63.7% since trade filed Nov 8, 2021 | Discretionary sale | 4,040 | $83.29 | $336K | −63.7% | Nov 8, 2021 |
| Oct 29, 2021 | Hill John W (Director) 9,235 shares $86.97 −65.3% since trade filed Nov 2, 2021 | Discretionary sale | 9,235 | $86.97 | $803K | −65.3% | Nov 2, 2021 |
| Aug 9, 2021 | Hill John W (Director) 6,160 shares $85.77 filed Aug 11, 2021 | Discretionary sale | 6,160 | $85.77 | $528K | – | Aug 11, 2021 |
| Apr 30, 2021 | Kaplan Laura Cox (Director) 1,062 shares $869.03 filed May 3, 2021 | Discretionary sale | 1,062 | $869.03 | $923K | – | May 3, 2021 |
| Mar 23, 2021 | SAINT FREDERICK G. (Officer) 7,834 shares $831.70 filed Mar 25, 2021 | Discretionary sale | 7,834 | $831.70 | $6.5M | – | Mar 25, 2021 |
| Mar 16, 2021 | Wheeler Scott T (CFO) 7,326 shares $843.28 filed Mar 17, 2021 | Discretionary sale | 7,326 | $843.28 | $6.2M | – | Mar 17, 2021 |
| Mar 10, 2021 | FLORANCE ANDREW C (CEO) 20K shares $818.37 filed Mar 11, 2021 | Discretionary sale | 20K | $818.37 | $16M | – | Mar 11, 2021 |
| Sep 2, 2020 | Ruggles Lisa (Officer) 7,596 shares $870.00 filed Sep 3, 2020 | Discretionary sale | 7,596 | $870.00 | $6.6M | – | Sep 3, 2020 |
| Aug 27, 2020 | FLORANCE ANDREW C (CEO) 16K shares $851.66 filed Aug 28, 2020 | Discretionary sale | 16K | $851.66 | $13M | – | Aug 28, 2020 |
| Aug 26, 2020 | FLORANCE ANDREW C (CEO) 16K shares $848.16 filed Aug 28, 2020 | Discretionary sale | 16K | $848.16 | $13M | – | Aug 28, 2020 |
“Since trade” compares with the latest insider-implied price, not a market quote: these pages are built from filings alone. A role here is the one on that day's Form 4, so somebody promoted since appears under both titles.
Filing hygiene
161 Forms 4, 3 years
12 filed late
2 amendments
3.6 avg. days to file
How to read this
A Form 4 transaction code decides everything. P is an open-market purchase and S an open-market sale; those two are the only codes where an insider chose to trade. A is a grant, M an option exercise or vesting, F shares withheld to cover tax, G a gift. Most “insiders dumped billions” headlines are code F and M mechanics.
Sales flagged 10b5-1 run on a plan the insider adopted in advance; since 2023 every Form 4 carries that flag. Buys have historically predicted returns, sales mostly have not, and this page states filings, not advice.