CSTL Insider Trading & Form 4 Activity
Net flow — last 12 months
Monthly net of insider buys minus sells. Green months indicate net buying; red months indicate net selling.
Most active insiders
Ranked by total transaction value over the last 90 days.
Recent transactions
Every Form 4 transaction for CSTL, newest first.
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About CSTL insider trading data
Form 4 is the SEC filing required when an officer, director, or 10% owner of a public company buys or sells the company's stock. By law, these filings must be submitted within two business days of the trade. Tracenotes pulls every Form 4 filing for CSTL from EDGAR, parses it, and surfaces the activity on this page.
What insider buying tells you. Open-market purchases by insiders are widely studied as a meaningful signal. Unlike stock awards (which are compensation, not conviction), an executive spending their own money to buy shares of the company they run is a vote of confidence. Studies have found insider-buying clusters — three or more insiders buying within a short window — outperform the broader market over the following year.
What insider selling tells you. Selling is noisier. Many sales are pre-scheduled under SEC Rule 10b5-1 plans, which let insiders sell on a fixed schedule regardless of company news. We label these "10b5-1" so you can see them. Discretionary sales — sales not tied to a plan — are more meaningful, especially when multiple insiders sell in quick succession.
Tracenotes methodology. We scan EDGAR daily for new Form 4 filings, parse them into individual transactions, and detect clusters when three or more distinct insiders buy or sell within a 14-day window. The data on this page covers the last 12 months. For deeper analysis, Tracenotes also runs language-change detection on 10-K and 10-Q filings — that's our core product.
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Frequently asked questions
What is a Form 4 filing?
Form 4 is the SEC disclosure required when a company insider — an officer, director, or 10% owner — buys or sells the company's stock. By law these filings must be submitted within two business days of the trade.
Is insider buying CSTL always bullish?
Open-market purchases by insiders are widely viewed as a bullish signal because executives are spending their own money. Stock awards and option exercises are part of compensation and don't carry the same weight, which is why we treat them separately on this page.
What is a 10b5-1 trade?
A trade made under SEC Rule 10b5-1, which lets insiders pre-schedule sales weeks or months in advance. These sales execute on a fixed plan regardless of company news, so they're a weaker signal than discretionary sales. We label them with a "10b5-1" tag.
What is an insider cluster?
A cluster is when three or more distinct insiders buy or sell within a 14-day window. Clusters are studied as stronger signals than single trades because multiple people independently reach the same view. We surface active clusters on CASTLE BIOSCIENCES INC (CSTL) when they form.
Where does CSTL insider trading data come from?
Every Form 4 filing for CSTL is sourced directly from SEC EDGAR. Tracenotes scans EDGAR daily, parses each Form 4 into individual transactions, and updates this page within hours of new filings.
Nothing on this page constitutes investment advice. Form 4 data is sourced from SEC EDGAR and provided for research purposes only.
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