Castle Biosciences officer plans sale of 29K shares
Officer Derek Maetzold and related trusts file a Rule 144 notice to sell Castle Biosciences common stock under a Rule 10b5-1 selling plan.
Rhea-AI Filing Summary
Castle Biosciences, Inc. (CSTL) is the issuer for a Form 144 notice filed on behalf of officer Derek Maetzold covering proposed sales of up to 29,014 shares of common stock through Goldman Sachs & Co. LLC. The filing states that these sales are made under a selling plan dated June 2, 2026 intended to comply with Rule 10b5-1(c).
The shares to be sold include 17,164 shares by Derek Maetzold, 5,445 shares by the Derek Maetzold 2020 Irrevocable Trust, and 6,405 shares by the Maetzold Descendants 2020 Trust, including shares acquired via compensation-related stock options and gifts. The filing also lists multiple common stock sales in the prior three months by Maetzold and related trusts.
Positive
- None.
Negative
- None.
Key Figures
Shares to be sold under Form 144: 29,014 shares
Shares to be sold by Derek Maetzold: 17,164 shares
Shares to be sold by Derek Maetzold 2020 Irrevocable Trust: 5,445 shares
+5 more
8 metrics
Shares to be sold under Form 144
29,014 shares
Common stock of Castle Biosciences covered by the notice
Shares to be sold by Derek Maetzold
17,164 shares
Included in the total shares to be sold
Shares to be sold by Derek Maetzold 2020 Irrevocable Trust
5,445 shares
Included in the total shares to be sold
Shares to be sold by Maetzold Descendants 2020 Trust
6,405 shares
Included in the total shares to be sold
Selling plan date
June 2, 2026
Date of selling plan intended to comply with Rule 10b5-1(c)
Date of Notice
September 11, 2026
Form 144 notice date for the planned sales
Example sale amount
20,356 shares for $632,020.39
Common stock sale by Derek Maetzold on August 4, 2026
Example option-related acquisition
17,164 shares
Common stock acquired as compensation via stock options on May 10, 2018
Key Terms
Form 144, Rule 144, Rule 10b5-1(c), cashless exercise / same-day sale, +1 more
5 terms
Form 144 regulatory
"144: Filer Information"
Form 144 is a document that investors must file with the government when they plan to sell a large number of shares of a company's stock. It helps ensure transparency so everyone knows how many shares are being sold and when, which can impact the stock's price.
Rule 144 regulatory
"See the definition of "person" in paragraph (a) of Rule 144."
Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.
Rule 10b5-1(c) regulatory
"selling plan dated 06/02/2026 that is intended to comply with Rule 10b5-1(c)"
Rule 10b5-1(c) is an SEC guideline that lets company insiders set up a written, pre-planned schedule to buy or sell their company stock when they are not in possession of material, nonpublic information. For investors, it matters because such plans can reduce the appearance of insider trading by separating decisions from inside knowledge—like putting your trades on autopilot—while also requiring scrutiny since pre-planned trades can still affect market confidence and share value.
cashless exercise / same-day sale financial
"Compensation -- Cashless exercise / same-day sale"
selling plan financial
"The sales of shares set forth herein are made in connection with a selling plan"
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
What does Castle Biosciences (CSTL) disclose in this Form 144 filing?
The notice covers proposed sales of up to 29,014 shares of Castle Biosciences common stock for the account of officer Derek Maetzold, using Goldman Sachs & Co. LLC as broker, under a Rule 10b5-1(c)-intended selling plan dated June 2, 2026.
Was a Rule 10b5-1 plan used for the CSTL sales in this Form 144?
Yes. The remarks state that the sales of shares set forth are made in connection with a selling plan dated June 2, 2026 that is intended to comply with Rule 10b5-1(c).
What prior Castle Biosciences (CSTL) sales are reported for the past three months?
Numerous common stock sales are listed from June 15, 2026 through August 28, 2026 by Derek Maetzold and related trusts, with share amounts per transaction ranging from under 100 shares to over 20,000 shares, each with corresponding dollar amounts.
When was the Form 144 notice for CSTL dated and who signed it?
The Date of Notice is September 11, 2026. The signature block shows Goldman Sachs & Co. LLC signing on behalf of Derek Maetzold.
AI-generated analysis. How Rhea-AI works. Not financial advice.
