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Costar Group, Inc.

CSGP
Exchange
Nasdaq
Industry
Services-Business Services, NEC
SEC CIK
0001057352

No open-market purchases or sales by Costar Group, Inc. insiders were filed in the last 90 days; 764 institutions reported holding it in 13F filings for Q2 2026, worth $11.7B in total; superinvestors Akre Capital Management and Weitz Investment Management hold it.

Holders of 5% or more of CSGP

Holders whose latest Schedule 13D or 13G filing reports 5% or more of Costar Group, Inc., largest stake first. The change is against the holder's previous filing.

Holders of 5% or more of CSGP
HolderLatest formStakeChangeFirst filedLatest filingFiling
Vanguard Portfolio Management LLC13G9.12%38.3M sharesNewApr 29, 20261 filingApr 29, 2026SEC
Vanguard Capital Management LLC13G7.53%31.6M sharesNewApr 29, 20261 filingApr 29, 2026SEC
BlackRock, Inc.13G/A7.50%31.8M shares–Apr 23, 20251 filingApr 23, 2025SEC
Bamco Inc13G5.30%21.6M shares–Feb 12, 20212 filingsAug 14, 2026SEC

Stakes are as of each holder's latest filing. Holders whose last filing was in the old format (before December 18, 2024) have no stake on record and are not listed, and after an acquisition or delisting holders usually stop filing.

13D and 13G filings

18 Schedule 13D and 13G filings on Costar Group, Inc., newest first, including old-format filings without a stake.

Schedule 13D and 13G filings on CSGP
Filed (ET)FilerFormStakeChangeEvent dateFiling
Aug 14, 202610:45 AM ETBamco Incand 3 others13G5.30%21.6M shares–Jun 30, 2026SEC
Apr 29, 20265:48 PM ETVanguard Capital Management LLC13G7.53%31.6M sharesNewMar 31, 2026SEC
Apr 29, 202612:51 PM ETVanguard Portfolio Management LLC13G9.12%38.3M sharesNewMar 31, 2026SEC
Mar 26, 20265:42 PM ETVanguard Group Inc13G/A0.00%0 shares–Below 5%Mar 13, 2026SEC
Apr 23, 20258:39 PM ETBlackRock, Inc.13G/A7.50%31.8M shares–Mar 31, 2025SEC
Feb 13, 2024Vanguard Group Inc13G/AOld format–––SEC
Jan 25, 20241:48 PM ETBlackRock Inc.13G/AOld format–––SEC
Feb 14, 2023Price T Rowe Associates Inc13G/AOld format–––SEC
Feb 9, 2023Vanguard Group Inc13G/AOld format–––SEC
Jan 30, 20234:03 PM ETBlackRock Inc.13G/AOld format–––SEC
Oct 11, 2022Vanguard Group Inc13G/AOld format–––SEC
Feb 14, 2022Price T Rowe Associates Inc13G/AOld format–––SEC
Feb 9, 2022Vanguard Group Inc13G/AOld format–––SEC
Feb 1, 20225:08 PM ETBlackRock Inc.13G/AOld format–––SEC
Feb 16, 2021Price T Rowe Associates Inc13G/AOld format–––SEC
Feb 12, 2021Bamco Inc13G/AOld format–––SEC
Feb 10, 2021Vanguard Group Inc13G/AOld format–––SEC
Jan 29, 20219:57 AM ETBlackRock Inc.13G/AOld format–––SEC

Form 144: proposed insider sales

25 notices from officers, directors and other affiliates planning to sell Costar Group, Inc. shares, newest first.

Form 144 notices for CSGP
Filed (ET)SellerShares to sellMarket valuePlanned saleBrokerFiling
Aug 5, 20261:58 PM ETHill John WDirector3.50K$106.1KAug 5, 2026Ameritas Investment CorpSEC
Nov 13, 20253:57 PM ETHill John WDirector · Family member of an insider2.25K$151.9KNov 13, 2025Ameritas Investment CorpSEC
Aug 28, 20255:02 PM ETFrederick SaintOfficer25.0K$2.26MAug 28, 2025Morgan Stanley Smith Barney LLC Executive Financial ServicesSEC
Jul 28, 20254:10 PM ETFrederick SaintOfficer25.0K$2.33MJul 28, 2025Morgan Stanley Smith Barney LLC Executive Financial ServicesSEC
Jun 11, 20255:35 PM ETFrederick SaintOfficer · Director25.0K$2.03MJun 11, 2025Morgan Stanley Smith Barney LLC Executive Financial ServicesSEC
May 12, 20254:28 PM ETMichael KleinFormer Board Member, retired less than 90 days ago267.9K$20.1MMay 12, 2025UBS Financial Services IncSEC
May 9, 20254:45 PM ETMichael KleinFormer Board Member, retired less than 90 days ago32.1K$2.42MMay 9, 2025UBS Financial Services IncSEC
Dec 10, 20242:37 PM ETHill John WDirector2.73K$215.1KDec 10, 2024Ameritas Investment CorpSEC
Nov 27, 20244:32 PM ETChristopher J NassetaDirector1.68K$134.3KNov 27, 2024Goldman Sachs & Co. LLCSEC
Nov 26, 20244:17 PM ETMichael DesmaraisOfficer5.50K$439.3KNov 26, 2024Morgan Stanley Smith Barney LLC Executive Financial ServicesSEC
Oct 25, 20244:58 PM ETMichael KleinDirector71.6K$5.30MOct 25, 2024UBS Financial Services IncSEC
Jul 30, 20242:12 PM ETHill John WDirector1.32K$103.0KJul 30, 2024Ameritas Investment CorpSEC
May 16, 20244:48 PM ETFrederick SaintOfficer2.50K$221.1KMay 16, 2024Morgan Stanley Smith Barney LLC Executive Financial ServicesSEC
May 9, 20244:47 PM ETLisa C. RugglesOfficer20.0K$1.82MMay 9, 2024Morgan Stanley Smith Barney LLC Executive Financial ServicesSEC
Apr 26, 20244:16 PM ETScott WheelerOfficer122.7K$11.4MApr 26, 2024Morgan Stanley Smith Barney LLC Executive Financial ServicesSEC
Apr 26, 20244:10 PM ETMichael DesmaraisOfficer3.80K$352.2KApr 26, 2024Morgan Stanley Smith Barney LLC Executive Financial ServicesSEC
Nov 28, 20238:59 AM ETHill John WDirector3.02K$250.0KNov 28, 2023Ameritas Investment CorpSEC
Nov 8, 20234:48 PM ETChristopher J NassettaDirector1.50K$116.8KNov 8, 2023Goldman Sachs & Co. LLCSEC
Jun 30, 20235:36 PM ETLisa RugglesOfficer30.5K$2.79MJun 30, 2023Morgan Stanley Smith Barney LLCSEC
Jun 28, 20235:16 PM ETScott WheelerOfficer21.5K$1.92MJun 28, 2023Morgan Stanley Smith Barney LLCSEC
Jun 27, 20232:10 PM ETSimuro FrankOfficer92.3K$8.10MJun 27, 2023Vanguard Marketing CorporationSEC
Jun 23, 202311:26 AM ETHill John WDirector1.50K$125.9KJun 23, 2023Ameritas Investment corpSEC
Jun 12, 20237:08 PM ETScott WheelerOfficer24.7K$1.99MJun 12, 2023Morgan Stanley Smith Barney LLCSEC
Jun 7, 20236:34 PM ETFrederick SaintOfficer30.0K$2.41MJun 7, 2023Morgan Stanley Smith Barney LLCSEC
Apr 28, 20235:21 PM ETAndrew FloranceOfficer · Director360.5K$27.7MApr 28, 2023Morgan Stanley Smith Barney LLCSEC