Andrew C. Florance, the founder and chief executive officer of CoStar Group, Inc. (NASDAQ: CSGP), disclosed an open-market purchase of company stock in a Form 4 filing tied to a transaction dated August 4, 2026. Florance bought 83,300 shares at a price of $29.89 per share, a total outlay of $2,489,837.00 paid with his own money.
Following the purchase, Florance’s directly held stake in CoStar Group stands at 1,806,165 shares. The filing lists his roles as both Founder and CEO and as a member of the company’s board of directors, giving him a dual vantage point on the commercial real estate data and analytics firm’s operations and strategic direction.
Why the Buy Stands Out
Open-market purchases by chief executives are watched closely by market observers because they represent a discretionary use of personal capital rather than a transaction tied to routine compensation, such as an option exercise or a scheduled equity grant. Our classification tags this filing as an open market buy, the category of insider activity that tends to draw the most attention from those who track SEC disclosures, since it signals the insider chose to commit additional personal funds to shares they already hold in significant quantity.
At $29.89 per share, the purchase price offers a specific data point for anyone comparing the transaction to where CSGP has traded in recent sessions. The founder-CEO’s decision to add to an already substantial position of over 1.8 million shares held directly is notable simply given the scale of his existing exposure to the company’s stock price.
Context Without a Recommendation
Academic research on insider trading patterns has found that clustered buying activity among corporate insiders, particularly by founders and chief executives, can correlate with subsequent periods of relative outperformance, though the relationship is statistical across large samples rather than predictive for any single filing. This report is limited to what appears in the Form 4 disclosure itself and does not constitute investment guidance or a suggestion to trade CSGP shares.
CoStar Group operates as a provider of commercial real estate information, analytics, and online marketplaces, and Florance has led the company since its founding. His continued direct ownership stake, now at 1,806,165 shares after this transaction, keeps his personal financial interest closely tied to the company’s share price performance going forward.
Further details of the transaction, including the exact filing date and any accompanying footnotes from the insider or the company, are available in the underlying SEC Form 4 document.
→ See all CSGP coverage on WhoIsBuyingNow
Source: original SEC Form 4 filing.