The Filings Report

CoStar Group Inc insider trading

CSGPfinancial statementsForm 4 filings on EDGAR113 transactions since Nov 3, 2024

From August 6, 2026 to November 3, 2026, 0 insiders at CoStar Group Inc bought $0 of stock in the open market, and 1 sold $147K. Officers and directors accounted for $0 of purchases and $147K of sales. The last reported transaction was a tax withholding by Rossmann Robin Jack on October 15, 2026.

The answer card and chart use the same period. Change the range above the chart to update both. Form 4 filings through October 16, 2026; awards, option exercises, tax withholding and gifts are excluded from these totals.

Stock price and insider activity

Daily price candles with insider purchases and sales directly beneath them on the same timeline. Bars show individual days; totals sum all days in the selected period.

CSGP daily priceSplit-adjusted prices in US dollars

Bought $0Sold $147KAug 6, 2026 – Nov 3, 2026

Nov 3, 2026O $31.34 · H $31.37 · L $30.42 · C $31.32Bought $0 (0)Sold $0 (0)
$26$29$31$34$362026-08-06: open $29.89, high $30.22, low $29.27, close $29.582026-08-07: open $30.05, high $31.68, low $30.04, close $30.242026-08-10: open $30.04, high $31.49, low $30.04, close $31.482026-08-11: open $31.25, high $31.52, low $30.65, close $31.122026-08-12: open $30.65, high $31.08, low $30.22, close $30.502026-08-13: open $30.68, high $33.10, low $30.68, close $33.052026-08-14: open $33.28, high $33.30, low $31.86, close $32.382026-08-17: open $31.95, high $32.15, low $30.99, close $31.352026-08-18: open $32.03, high $32.29, low $31.30, close $31.382026-08-19: open $31.28, high $33.82, low $31.20, close $33.732026-08-20: open $33.46, high $33.63, low $31.72, close $32.262026-08-21: open $32.51, high $33.26, low $31.99, close $32.262026-08-24: open $32.52, high $32.90, low $32.29, close $32.842026-08-25: open $32.59, high $33.28, low $32.25, close $32.812026-08-26: open $32.31, high $32.92, low $31.74, close $32.142026-08-27: open $32.05, high $32.49, low $31.29, close $31.342026-08-28: open $31.71, high $32.59, low $31.45, close $32.222026-08-31: open $31.95, high $32.59, low $31.79, close $32.072026-09-01: open $32.00, high $32.46, low $31.40, close $31.982026-09-02: open $31.97, high $32.65, low $31.20, close $31.262026-09-03: open $31.84, high $32.79, low $31.22, close $31.682026-09-04: open $31.25, high $31.33, low $30.32, close $30.912026-09-08: open $30.55, high $30.63, low $29.66, close $30.342026-09-09: open $30.02, high $30.29, low $29.33, close $29.582026-09-10: open $29.64, high $30.14, low $28.79, close $29.492026-09-11: open $29.72, high $30.60, low $29.71, close $30.462026-09-14: open $31.17, high $31.83, low $30.75, close $31.522026-09-15: open $31.15, high $31.79, low $30.70, close $31.562026-09-16: open $31.25, high $31.43, low $30.27, close $30.362026-09-17: open $30.48, high $30.59, low $29.24, close $29.302026-09-18: open $29.30, high $29.91, low $28.96, close $29.092026-09-21: open $29.24, high $29.64, low $28.84, close $29.042026-09-22: open $29.51, high $29.63, low $28.31, close $28.772026-09-23: open $28.69, high $28.69, low $27.89, close $28.262026-09-24: open $28.18, high $28.52, low $27.28, close $27.862026-09-25: open $27.73, high $28.63, low $27.63, close $28.092026-09-28: open $27.68, high $27.75, low $26.85, close $27.022026-09-29: open $26.84, high $27.18, low $26.52, close $26.952026-09-30: open $27.03, high $27.55, low $26.86, close $27.402026-10-01: open $27.91, high $28.23, low $27.10, close $27.722026-10-02: open $27.48, high $27.81, low $27.15, close $27.382026-10-05: open $27.25, high $27.68, low $27.18, close $27.662026-10-06: open $27.70, high $28.20, low $27.46, close $27.632026-10-07: open $27.77, high $27.87, low $27.17, close $27.602026-10-08: open $27.60, high $29.83, low $27.58, close $29.812026-10-09: open $30.02, high $30.16, low $29.54, close $29.672026-10-12: open $29.67, high $29.90, low $29.03, close $29.212026-10-13: open $29.48, high $30.02, low $29.11, close $30.002026-10-14: open $29.98, high $30.21, low $29.30, close $30.112026-10-15: open $30.59, high $32.50, low $30.59, close $32.002026-10-16: open $32.39, high $32.65, low $31.59, close $32.312026-10-19: open $31.93, high $32.05, low $31.39, close $31.812026-10-20: open $32.39, high $33.31, low $32.39, close $33.052026-10-21: open $32.95, high $33.29, low $32.68, close $32.902026-10-22: open $33.98, high $35.63, low $33.43, close $35.452026-10-23: open $35.22, high $35.59, low $33.79, close $33.922026-10-26: open $33.94, high $34.26, low $33.02, close $33.702026-10-27: open $33.69, high $33.69, low $31.87, close $31.942026-10-28: open $30.00, high $30.68, low $26.86, close $27.542026-10-29: open $27.69, high $28.39, low $27.07, close $28.142026-10-30: open $28.85, high $30.26, low $28.36, close $30.172026-11-02: open $30.04, high $32.24, low $30.01, close $31.822026-11-03: open $31.34, high $31.37, low $30.42, close $31.32Insider purchases / sales · USD$200K$0−$200K2026-08-07: 0 purchases ($0), 1 sales ($147K)Aug 6Aug 28Sep 21Oct 13Nov 3

purchases above zero; sales below. Both use the transaction date and the same dollar scale. Hover, tap, or use arrow keys to inspect a date. Awards, exercises, tax withholding and gifts are excluded.

Dates with prices or insider activity are spaced evenly; empty weekends and holidays are omitted. Prices through Nov 3, 2026. Insider data through Nov 3, 2026. Prices are adjusted for splits; transaction values are reported dollars.

Every transaction

113 transactions from November 3, 2024 to November 3, 2026, newest first. Open-market purchases and sales are coloured; awards, exercises, tax withholding and gifts are grey and not counted.

TradedInsiderRoleTransactionSharesPriceValueHeld afterFiled
Oct 15, 2026Rossmann Robin JackChief Financial Officertax withholding756$32.00$24K85,935Oct 16, 2026
Aug 7, 2026Cann Cynthia CammettChief Accounting Officeropen-market sale4,788$30.78$147K18,822Aug 10, 2026
Aug 5, 2026Hill John WDirectoropen-market sale3,500$30.21$106K22,993Aug 10, 2026
Aug 4, 2026Florance Andrew CFounder and CEO, Directoropen-market buy83,300$29.89$2M2MAug 5, 2026
Aug 1, 2026Cann Cynthia CammettChief Accounting Officertax withholding1,077$28.76$31K23,610Aug 4, 2026
Aug 1, 2026Saint Frederick G.President, Marketplacestax withholding1,436$28.76$41K278,415Aug 4, 2026
Jul 1, 2026Lown Christian M.Chief Financial Officertax withholding5,597$29.36$164K129,653Jul 6, 2026
Jun 23, 2026Glaser Rachel CDirectoraward8,262$0.00—12,419Jun 24, 2026
Jun 23, 2026Berisford John LDirectoraward8,262$0.00—11,235Jun 24, 2026
Jun 23, 2026Hill John WDirectoraward8,262$0.00—26,493Jun 24, 2026
Jun 23, 2026Brunner Angelique G.Directoraward8,262$0.00—18,428Jun 24, 2026
Jun 23, 2026Musslewhite Robert WDirectoraward8,262$0.00—26,539Jun 24, 2026
Jun 23, 2026Sams Louise SDirectoraward8,262$0.00—28,671Jun 24, 2026
Jun 23, 2026McCarthy Christine MDirectoraward8,262$0.00—11,585Jun 24, 2026
Jun 15, 2026Cann Cynthia CammettChief Accounting Officertax withholding461$32.04$15K24,687Jun 16, 2026
May 1, 2026Florance Andrew CPresident and CEO, Directoropen-market buy68,330$35.17$2M2MMay 4, 2026
May 1, 2026Florance Andrew CPresident and CEO, Directoropen-market buy3,100$35.82$111K2MMay 4, 2026
Mar 15, 2026Boxer GeneGeneral Counsel and Secretarytax withholding482$43.63$21K95,463Mar 17, 2026
Mar 15, 2026Ruggles LisaSenior VP, Global Operationstax withholding2,977$43.63$130K174,915Mar 17, 2026
Mar 15, 2026Boxer GeneGeneral Counsel and Secretarytax withholding428$43.63$19K95,517Mar 17, 2026
Mar 15, 2026Simuro FrankChief Technology Officertax withholding11,107$43.63$485K414,491Mar 17, 2026
Mar 15, 2026Desmarais Michael JChief Human Resources Officertax withholding2,873$43.63$125K87,725Mar 17, 2026
Mar 15, 2026Cann Cynthia CammettChief Accounting Officertax withholding1,194$43.63$52K25,148Mar 17, 2026
Mar 10, 2026Cann Cynthia CammettChief Accounting Officeraward4,374——26,342Mar 11, 2026
Mar 10, 2026Florance Andrew CPresident and CEO, Directoraward124,162——2MMar 11, 2026
Mar 10, 2026Lown Christian M.Chief Financial Officeraward12,268——135,250Mar 11, 2026
Mar 10, 2026Boxer GeneGeneral Counsel and Secretaryaward21,920——95,945Mar 11, 2026
Mar 10, 2026Desmarais Michael JChief Human Resources Officeraward17,676——90,598Mar 11, 2026
Mar 6, 2026Sams Louise SDirectoropen-market buy1,000$48.36$48K20,409Mar 9, 2026
Mar 2, 2026Glaser Rachel CDirectoropen-market buy1,000$44.94$45K4,157Mar 3, 2026
Mar 2, 2026Saint Frederick G.President, Marketplacesopen-market buy20,000$45.33$907K279,851Mar 3, 2026
Mar 1, 2026Lown Christian M.Chief Financial Officertax withholding7,175$44.63$320K122,982Mar 3, 2026
Mar 1, 2026Florance Andrew CPresident and CEO, Directortax withholding59,593$44.63$3M2MMar 3, 2026
Mar 1, 2026Boxer GeneGeneral Counsel and Secretarytax withholding4,547$44.63$203K74,025Mar 3, 2026
Mar 1, 2026Desmarais Michael JChief Human Resources Officertax withholding6,353$44.63$284K72,922Mar 3, 2026
Mar 1, 2026Cann Cynthia CammettChief Accounting Officertax withholding1,385$44.63$62K21,968Mar 3, 2026
Mar 1, 2026Ruggles LisaSenior VP, Global Operationstax withholding8,931$44.63$399K177,892Mar 3, 2026
Mar 1, 2026Simuro FrankChief Technology Officertax withholding18,702$44.63$835K425,598Mar 3, 2026
Mar 1, 2026Saint Frederick G.President, Marketplacestax withholding11,096$44.63$495K259,851Mar 3, 2026
Feb 27, 2026Florance Andrew CPresident and CEO, Directoropen-market buy55,720$44.52$2M2MMar 2, 2026
Feb 19, 2026Simuro FrankChief Technology Officerdisposition to issuer30,727$0.00—448,721Feb 23, 2026
Feb 19, 2026Simuro FrankChief Technology Officertax withholding4,421$49.07$217K444,300Feb 23, 2026
Feb 19, 2026Saint Frederick G.President, Marketplacesdisposition to issuer17,583$0.00—273,096Feb 23, 2026
Feb 19, 2026Saint Frederick G.President, Marketplacestax withholding2,149$49.07$105K270,947Feb 23, 2026
Feb 19, 2026Florance Andrew CPresident and CEO, Directordisposition to issuer104,983$0.00—2MFeb 23, 2026
Feb 19, 2026Florance Andrew CPresident and CEO, Directortax withholding19,221$49.07$943K2MFeb 23, 2026
Feb 19, 2026Ruggles LisaSenior VP, Global Operationstax withholding3,219$49.07$158K186,823Feb 23, 2026
Feb 19, 2026Ruggles LisaSenior VP, Global Operationsdisposition to issuer17,583$0.00—190,042Feb 23, 2026
Feb 15, 2026Simuro FrankChief Technology Officertax withholding4,151$44.99$187K479,448Feb 18, 2026
Feb 15, 2026Florance Andrew CPresident and CEO, Directortax withholding17,482$44.99$787K2MFeb 18, 2026

Who the insiders are

Everyone who reported a transaction since November 3, 2024, by open-market value over twelve months. Shares held are after the insider’s latest directly held transaction.

InsiderRoleLast transactionKindShares heldBought, 12 monthsSold, 12 monthsSales under a plan
Florance Andrew CFounder and CEO, DirectorAug 4, 2026open-market buy2M$7M (4)——
Saint Frederick G.President, MarketplacesAug 1, 2026tax withholding278,415$907K (1)——
Cann Cynthia CammettChief Accounting OfficerAug 7, 2026open-market sale18,822—$274K (2)0 of 2
Hill John WDirectorAug 5, 2026open-market sale22,993—$260K (2)0 of 2
Sams Louise SDirectorJun 23, 2026award28,671$48K (1)——
Glaser Rachel CDirectorJun 23, 2026award12,419$45K (1)——
Ruggles LisaSenior VP, Global OperationsMar 15, 2026tax withholding174,915———
Simuro FrankChief Technology OfficerMar 15, 2026tax withholding414,491———
Boxer GeneGeneral Counsel and SecretaryMar 15, 2026tax withholding95,463———
Desmarais Michael JChief Human Resources OfficerMar 15, 2026tax withholding87,725———
Lown Christian M.Chief Financial OfficerJul 1, 2026tax withholding129,653———
Berisford John LDirectorJun 23, 2026award11,235———
Brunner Angelique G.DirectorJun 23, 2026award18,428———
Musslewhite Robert WDirectorJun 23, 2026award26,539———
McCarthy Christine MDirectorJun 23, 2026award11,585———
Rossmann Robin JackChief Financial OfficerOct 15, 2026tax withholding85,935———
Klein Michael RDirectorDec 10, 2024gift2M———
Nassetta Christopher JDirectorNov 27, 2024open-market sale229,715———

Questions

Are CoStar Group Inc insiders buying or selling?

Over the twelve months to November 3, 2026, 2 insiders at CoStar Group Inc sold $534K of stock in the open market, all by officers and directors, and 4 insiders bought $8M, all by officers and directors. Net, insiders bought $8M. Only open-market purchases and sales are counted.

Who sold the most CoStar Group Inc stock in the last year?

Cann Cynthia Cammett (Chief Accounting Officer) sold $274K in 2 open-market sales over the twelve months to November 3, 2026.

Do CoStar Group Inc executives sell under 10b5-1 plans?

0 of the 4 open-market sales in the last twelve months (0%) were reported as made under a Rule 10b5-1 trading plan, set up in advance. A sale under a plan is still counted as a sale.

What counts as insider buying here?

Only open-market purchases (Form 4 code P) and sales (code S) by officers, directors and 10% owners. Stock awards, option exercises, shares withheld for tax and gifts are listed in the table but never counted as buying or selling.

More on CoStar Group Inc

From Form 4, 4/A and 5 filings with the SEC. A record of insider transactions, not a recommendation.