Costar Group Inc (CSGP) insider trading
Recent insider transactions reported to the SEC on Form 4 — directors and officers buying or selling their own company’s stock. Sourced directly from public SEC filings, latest filed Oct 16, 2026.
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- Filings shown
- 9
- Open-market buys
- 1
- Open-market sells
- 2
- Buys, 10b5-1 box not checked
- 1 of 1
Counts cover the 9 most recent Form 4 filings Tradune holds for CSGP (filed Jun 24 – Oct 16, 2026); the score below covers only the trailing 90 days (1 buy, 2 sells). No completed check of CSGP's Form 4 list on SEC EDGAR is on record yet; the latest CSGP filing Tradune holds was filed Oct 16, 2026. This is not guaranteed to be the complete record — see CSGP's full Form 4 filing history on SEC EDGAR.
Open-market activity, last 90 days
Purchases (Form 4 code P) and sales (code S) on the 7 filings Tradune holds for CSGP filed Aug 4 – Oct 16, 2026. Grants, exercises, tax withholding and the other Form 4 transaction codes are left out.
2 open-market sales by Rule 10b5-1 checkbox
- On filings with the 10b5-1 box checked
- 0 sales· 0 sh
- checkbox disclosed
- On filings with the box not checked
- 2 sales· 8,288 sh
- not proof that no plan exists
- Not comparable
- 0 sales· 0 sh
- filed before Apr 1, 2023, or no checkbox value in the filing data
Counts are Form 4 lines as filed. The checkbox is one per filing, so every sale on a filing with the box checked is counted there even if only some of its transactions were under a plan; it records what the filer disclosed, and the three categories are not a judgement about why a sale was made.
| Insider | Buys | Sells | Shares bought | Shares sold | Value |
|---|---|---|---|---|---|
| Andrew C. FloranceFounder and CEO | 1 | 0 | 83,300 | — | +$2,489,837 |
| Cynthia Cammett CannChief Accounting Officer | 0 | 1 | — | 4,788 | −$147,375 |
| John W. HillDirector | 0 | 1 | — | 3,500 | −$105,735 |
Value = shares × the price reported on each Form 4 (+ purchases, − sales); every open-market line in this window disclosed a price.
Summarises ~90 days of public SEC Form 4 activity — more distinct buyers, officer involvement and net buying score higher. A description of filing activity, not a rating or buy signal. How this score is computed →
Weekly signal history
CSGP appeared in 1 archived weekly edition as a top net buyer. These are frozen weekly snapshots, not a complete filing history.
- Week of Sep 9, 2026 1 open-market buy · $2,236,727 net
An entry means this company met that edition’s displayed cluster or top-buyer threshold. Missing weeks do not mean no insider transaction occurred. All figures are derived from SEC Form 4 filings; open-market buys minus sales are shown as net only when every transaction value was disclosed.
How to read this: an open-market purchase (Form 4 code P) is a buy at the market price with the insider’s own money, as opposed to a grant, award or option exercise; an open-market sale is code S. When two or more distinct insiders report open-market purchases in the same 90-day window, this site labels that a cluster — a definition, not a forecast; see insider cluster buying. “Held after” is Form 4 Table I column 5; “Change” = shares ÷ holdings before the trade (held after − shares for an acquisition, held after + shares for a disposition).
Insider Buying at CSGP
Insiders reported 1 open-market purchase of CSGP between Jun 24, 2026 and Oct 16, 2026, across 1 distinct buyer. The most recent purchase was reported by Andrew C. Florance (Founder and CEO) on Aug 4, 2026. Grants, option exercises, and tax-withholding transactions are excluded from these counts.
Recent Form 4 filings
Source: SEC EDGAR Form 4 · transaction codes explained
| Transaction | Shares | Price | Held after | Change† | Date |
|---|---|---|---|---|---|
| Tax withholding | 756 | $32.00 | 85,935 | −0.9% | Oct 15, 2026 |
† change in this filer’s own reported holding line (Form 4 Table I, col. 5), not of total company ownership; small prior holdings produce large percentages, so under 100 shares the prior holding is shown instead.
| Transaction | Shares | Price | Held after | Change† | Date |
|---|---|---|---|---|---|
| Open-market sale 10b5-1 box not checked | 4,788 | $30.78 | 18,822 | −20% | Aug 7, 2026 |
“10b5-1 box checked” = the filer checked the Form 4 box stating that a transaction on the filing was made under a plan intended to satisfy Rule 10b5-1(c); “10b5-1 box not checked” = the box was left blank, which does not prove that no plan exists. The box applies to Form 4s filed from April 1, 2023; older filings, and boxes we could not read, carry no tag. What the 10b5-1 box means.
| Transaction | Shares | Price | Held after | Change† | Date |
|---|---|---|---|---|---|
| Open-market sale 10b5-1 box not checked | 3,500 | $30.21 | 22,993 | −13% | Aug 5, 2026 |
| Transaction | Shares | Price | Held after | Change† | Date |
|---|---|---|---|---|---|
| Open-market purchase 10b5-1 box not checked | 83,300 | $29.89 | 1,806,165 | +4.8% | Aug 4, 2026 |
| Transaction | Shares | Price | Held after | Change† | Date |
|---|---|---|---|---|---|
| Tax withholding | 1,436 | $28.76 | 278,415 | −0.5% | Aug 1, 2026 |
| Transaction | Shares | Price | Held after | Change† | Date |
|---|---|---|---|---|---|
| Tax withholding | 1,077 | $28.76 | 23,610 | −4.4% | Aug 1, 2026 |
| Grant / award Restricted Stock Units | 26,078 | — | — | — | Jul 31, 2026 |
| Transaction | Shares | Price | Held after | Change† | Date |
|---|---|---|---|---|---|
| Grant / award Restricted Stock Units | 34,771 | — | — | — | Jul 31, 2026 |
| Transaction | Shares | Price | Held after | Change† | Date |
|---|---|---|---|---|---|
| Tax withholding | 5,597 | $29.36 | 129,653 | −4.1% | Jul 1, 2026 |
| Transaction | Shares | Price | Held after | Change† | Date |
|---|---|---|---|---|---|
| Grant / award | 8,262 | — | 12,419 | +199% | Jun 23, 2026 |
Insider filings reported around the same time
Other companies whose most recent Form 4 was filed closest to CSGP's (Oct 16, 2026).
Frequently asked about CSGP insider activity
How many insiders bought CSGP stock in these Form 4 filings?
1 distinct insider at Costar Group Inc reported 1 open-market purchase (Form 4 code P) of CSGP shares between Jun 24, 2026 and Oct 16, 2026, the most recent filed by Andrew C. Florance (Founder and CEO) on Aug 4, 2026. Grants, option exercises, and tax-withholding transactions are excluded from these counts.
Who filed the most recent Form 4 for CSGP?
The most recent Form 4 on this page was filed by Robin Jack Rossmann (Chief Financial Officer) on Oct 16, 2026, reporting 1 transaction. The original document is linked from the filing list above on SEC EDGAR. Amended filings (Form 4/A) may later revise reported figures.
What was the largest open-market CSGP insider purchase shown?
The largest open-market purchase among the filings shown was 83,300 CSGP shares at $29.89 (about $2,489,837) by Andrew C. Florance (Founder and CEO) on Aug 4, 2026. Value is shares × the price reported on the Form 4; its Rule 10b5-1 box is not checked.
Do the recent CSGP insider purchases have the Form 4 10b5-1 box checked?
No. The one CSGP open-market purchase shown was reported with the Rule 10b5-1 box not checked. A blank box records what the filer disclosed; it does not prove that no plan exists. Latest: Andrew C. Florance (Founder and CEO) on Aug 4, 2026, 83,300 shares.
New to Form 4s? The transaction codes, the 90-day window and the 0–100 score are defined on the insider-activity score methodology page.
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Track CSGP insider filings free →This score summarizes SEC Form 4 filing activity over the trailing 90 days. It is descriptive, not predictive — not a rating, recommendation, or investment advice. Data: SEC EDGAR (public domain), as filed; amendments may revise figures. Tradune is not a registered investment adviser.
Data as filed; amended filings (Form 4/A) may revise figures. Sales may occur under prearranged Rule 10b5-1 trading plans.