CoStar (CSGP) insider buying and selling
Every Table I transaction reported by directors and officers of S&P 500 companies on SEC Form 4 filings (2 business days to file): each row labeled with its official transaction code, nothing filtered out beforehand.
Open-market purchases (code P) are the rare signal, in green; sales (code S) are common and often pre-scheduled (10b5-1). Table II (derivatives) is not included: its prices are exercise prices, not market values. Guide: insider buying.
| Date | Ticker | Insider | Role | Shares | Price | Amount | % of stake | Type / filing |
|---|
Download these transactions as CSV No account, no sign-up. The data is public: it comes from SEC Form 4 filings.
CoStar Group, Inc. (CSGP) insider buying and selling: 6 purchases, 5 sales
60 Form 4 Table I transactions filed with the SEC by CoStar Group, Inc. insiders between 2025-09-02 and 2026-10-16 (15-month history): 6 open-market purchases and 5 sales, plus 49 transactions under other Form 4 codes, broken down one by one below. The largest open-market trade is a purchase of $2.5M by Florance Andrew C on 2026-05-01.
CoStar insider buying and selling over the last 12 months
Between Oct 21, 2025 and Oct 20, 2026, CoStar insiders filed 6 purchases worth $8.5M and 4 sales worth $534k on the open market. The net balance is on the buy side: $8.0M more bought than sold.
The biggest buyer was Florance Andrew C (Founder and CEO): $7.5M in 3 purchases, out of 4 different buyers. The biggest seller was Cann Cynthia Cammett (Chief Accounting Officer): $274k in 2 sales, out of 2 different sellers.
The largest trade of the period was a purchase of $2.5M on May 1, 2026, by Florance Andrew C (President and CEO). Form 4 on sec.gov (0001066061-26-000012).
None of the 4 sales carries the 10b5-1 plan flag on the Form 4 (sales scheduled months ahead).
The last three months show 1 purchase and 2 sales, against 1 and 0 in the three before. The latest purchase is from Aug 4, 2026; the latest sale from Aug 7, 2026.
Against its sector (Real Estate, 30 companies with an insider page on this site), over the same dates the median is 3.5 sales and 0 purchases on the open market. CoStar has more sales than 15 of the other 29, ranks 1 of 30 by net dollars bought, and 10 of the 30 have at least one purchase, CoStar included.
The 20 most important trades
The 6 open-market purchases first, then the rest, each type from largest to smallest. The full history is in the tool above, already searched.
See all 60 CSGP trades in the full history →
| Trade date | Filed | Insider | Role | Amount | Code | Filing |
|---|---|---|---|---|---|---|
| 2026-05-01 | 2026-05-04 | Florance Andrew C | President and CEO | $2.5M | P — Open-market purchase2 Form 4 footnotesF1 Average based on sales prices ranging from $34.67 to $35.67. F2 Average based on sales prices ranging from $35.68 to $36.00. | SEC |
| 2026-08-04 | 2026-08-05 | Florance Andrew C | Founder and CEO | $2.5M | P — Open-market purchaseForm 4 footnoteF1 Average based on sales prices ranging from $29.57 to $29.99. | SEC |
| 2026-02-27 | 2026-03-02 | Florance Andrew C | President and CEO | $2.5M | P — Open-market purchaseForm 4 footnoteF1 Average based on sales prices ranging from $44.08 to $44.74. | SEC |
| 2026-03-02 | 2026-03-03 | Saint Frederick G. | President, Marketplaces | $907k | P — Open-market purchaseForm 4 footnoteF2 Average based on sales prices ranging from $45.26 to $45.38 | SEC |
| 2026-03-06 | 2026-03-09 | Sams Louise S | Director | $48k | P — Open-market purchase | SEC |
| 2026-03-02 | 2026-03-03 | Glaser Rachel C | Director | $45k | P — Open-market purchaseForm 4 footnoteF1 This amount includes shares that were inadvertently omitted from the insider's prior filing. | SEC |
| 2025-08-28 | 2025-09-02 | Saint Frederick G. | President, Marketplaces | $2.3M | S — Open-market saleForm 4 footnoteF1 Average based on sales prices ranging from $90.30 to $90.38. | SEC |
| 2025-11-13 | 2025-11-17 | Hill John W | Director | $155k | S — Open-market sale | SEC |
| 2026-08-07 | 2026-08-10 | Cann Cynthia Cammett | Chief Accounting Officer | $147k | S — Open-market sale | SEC |
| 2025-11-13 | 2025-11-17 | Cann Cynthia Cammett | Chief Accounting Officer | $127k | S — Open-market saleForm 4 footnoteF1 Average based on sales prices ranging from $68.78 to $68.85. | SEC |
| 2026-08-05 | 2026-08-10 | Hill John W | Director | $106k | S — Open-market sale | SEC |
| 2026-03-01 | 2026-03-03 | Florance Andrew C | President and CEO | $2.7M | F — Tax withholding (shares surrendered for taxes)Form 4 footnoteF1 On February 27, 2026, the last preceding business day, the closing price of the Company's common stock on Nasdaq was $44.63. | SEC |
| 2026-02-19 | 2026-02-23 | Florance Andrew C | President and CEO | $943k | F — Tax withholding (shares surrendered for taxes)Form 4 footnoteF2 On February 19, 2026, the closing price of the Company's Common Stock on Nasdaq was $49.07. | SEC |
| 2026-03-01 | 2026-03-03 | Simuro Frank | Chief Technology Officer | $835k | F — Tax withholding (shares surrendered for taxes)Form 4 footnoteF1 On February 27, 2026, the last preceding business day, the closing price of the Company's common stock on Nasdaq was $44.63. | SEC |
| 2026-02-15 | 2026-02-18 | Florance Andrew C | President and CEO | $787k | F — Tax withholding (shares surrendered for taxes)Form 4 footnoteF1 On February 13, 2026, the last preceding business day, the closing price of the Company's common stock on Nasdaq was $44.99. | SEC |
| 2026-03-01 | 2026-03-03 | Saint Frederick G. | President, Marketplaces | $495k | F — Tax withholding (shares surrendered for taxes)Form 4 footnoteF1 On February 27, 2026, the last preceding business day, the closing price of the Company's common stock on Nasdaq was $44.63. | SEC |
| 2026-03-15 | 2026-03-17 | Simuro Frank | Chief Technology Officer | $485k | F — Tax withholding (shares surrendered for taxes)Form 4 footnoteF1 On March 13, 2026, the last preceding business day, the closing price of the Company's common stock on Nasdaq was $43.63. | SEC |
| 2026-03-01 | 2026-03-03 | Ruggles Lisa | Senior VP, Global Operations | $399k | F — Tax withholding (shares surrendered for taxes)Form 4 footnoteF1 On February 27, 2026, the last preceding business day, the closing price of the Company's common stock on Nasdaq was $44.63. | SEC |
| 2026-03-01 | 2026-03-03 | Lown Christian M. | Chief Financial Officer | $320k | F — Tax withholding (shares surrendered for taxes)Form 4 footnoteF1 On February 27, 2026, the last preceding business day, the closing price of the Company's common stock on Nasdaq was $44.63. | SEC |
| 2026-03-01 | 2026-03-03 | Desmarais Michael J | Chief Human Resources Officer | $284k | F — Tax withholding (shares surrendered for taxes)2 Form 4 footnotesF1 On February 27, 2026, the last preceding business day, the closing price of the Company's common stock on Nasdaq was $44.63. F2 Includes 157 shares acquired under the CoStar Group, Inc. Employee Stock Purchase Plan. | SEC |
The period balance: money in, money out
Across the Form 4 filings submitted between Sep 2, 2025 and Oct 16, 2026, CoStar Group, Inc. open-market activity adds up to 6 purchases worth $8.5M and 5 sales worth $2.8M. The net balance is $5.7M on the buy side.
Only codes P and S count, where an insider puts in or takes out their own money. A buying balance like CoStar Group, Inc.'s is the less common case in the S&P 500: its insiders are already paid in stock and still put in their own money. It is not a recommendation to buy or sell: it is what was filed.
Every transaction, code by code
| Code | What it means | Trades | Reported amount |
|---|---|---|---|
| F | Tax withholding (shares surrendered for taxes) | 26 | $9.0M |
| A | Grant or award | 19 | $0 |
| P | Open-market purchase | 6 | $8.5M |
| S | Open-market sale | 5 | $2.8M |
| D | Sale back to the issuer | 4 | $0 |
| Total | Everything filed in the period | 60 | $20.3M |
23 of the 60 rows carry no usable amount on the Form 4: they count as trades and add $0. The code labels come from the SEC index.
Who has traded
Over the 15 months of history, 16 distinct people or entities have filed CoStar Group, Inc. transactions: 4 bought on the open market and 3 sold. Counted by CIK, the fixed number the SEC gives each filer, and not by name, which each filer types their own way.
| Filer | Role | Transactions | Bought (count) | Sold (count) | Last filed |
|---|---|---|---|---|---|
| Florance Andrew C | Founder and CEO | 8 | $7.5M (3) | — | 2026-08-05 |
| Saint Frederick G. | President, Marketplaces | 7 | $907k (1) | $2.3M (1) | 2026-08-04 |
| Cann Cynthia Cammett | Chief Accounting Officer | 7 | — | $274k (2) | 2026-08-10 |
| Hill John W | Director | 4 | — | $260k (2) | 2026-08-10 |
| Sams Louise S | Director | 3 | $48k (1) | — | 2026-06-24 |
| Glaser Rachel C | Director | 3 | $45k (1) | — | 2026-06-24 |
| Ruggles Lisa | Senior VP, Global Operations | 5 | — | — | 2026-03-17 |
| Simuro Frank | Chief Technology Officer | 5 | — | — | 2026-03-17 |
Shown here are the 8 who moved the most money, out of 16. The rest are in the full history, one link above. The name links to all their trades, in any company. "Transactions" counts any code; the money, open market only. Role: from their latest filing.
Month by month
By the month the trade was executed, not the month it was filed; months with no trades show zero. The busiest month was Mar 2026: 3 purchases and 0 sales, worth $1.0M. 9 of the 15 months have none.
| Month | Purchases | Amount | Sales | Amount |
|---|---|---|---|---|
| Aug 2025 | 0 | $0 | 1 | $2.3M |
| Sep 2025 | 0 | $0 | 0 | $0 |
| Oct 2025 | 0 | $0 | 0 | $0 |
| Nov 2025 | 0 | $0 | 2 | $281k |
| Dec 2025 | 0 | $0 | 0 | $0 |
| Jan 2026 | 0 | $0 | 0 | $0 |
| Feb 2026 | 1 | $2.5M | 0 | $0 |
| Mar 2026 | 3 | $1.0M | 0 | $0 |
| Apr 2026 | 0 | $0 | 0 | $0 |
| May 2026 | 1 | $2.5M | 0 | $0 |
| Jun 2026 | 0 | $0 | 0 | $0 |
| Jul 2026 | 0 | $0 | 0 | $0 |
| Aug 2026 | 1 | $2.5M | 2 | $253k |
| Sep 2026 | 0 | $0 | 0 | $0 |
| Oct 2026 | 0 | $0 | 0 | $0 |
The last month may be partial: a Form 4 is filed up to two business days later. The table does not say whether the pattern is good or bad; it says when it happened.
CoStar Group, Inc. (CSGP) analysis page →
Other Real Estate companies with insider trades
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How to read this data
None of the 5 sales in the table is flagged as scheduled (10b5-1 plan), the kind signed months ahead and executed automatically. CoStar's 6 open-market purchases (code P) are the rare signal: insiders are already paid in stock, so buying more means putting in their own money. The latest filing is from Oct 16, 2026, and a Form 4 arrives up to two business days after the trade.
16 of the 20 rows in the table carry footnotes from the Form 4 itself, folded into the code column and copied verbatim; a row with no footnote means the filing has none.
Guide: Insider buying · all guides
What is behind these trades
The concepts on this page, explained from scratch in the Academy. Free, no account.
- What the efficiency hypothesis says and what it does NOT sayIf an insider's purchase is public and anyone can read it, is there any information left in it? That is the exact question that brings people here.
- Who really moves the market: the types of investorWho sits on the other side of each order, and where a company's own insiders fit among them.
- Supply, demand and price: why it rises and falls constantlyHow a piece of news ends up inside the price, and why the reaction to a filed sale is rarely the one you would expect.
Source: SEC EDGAR Form 4. This is a list of public facts, not financial advice or a recommendation to buy or sell.