Were the CSTL COO’s share sales made under a Rule 10b5-1 plan?

Yes. The filing states the transactions were made under a Rule 10b5-1 trading plan adopted on March 17, 2026. Such plans schedule trades in advance, providing a structured way for insiders to sell shares over time under preset instructions.

Castle Biosciences (CSTL) COO sells 8,586 shares under 10b5-1 plan

Filing Impact

(Moderate)

Filing Sentiment

(Negative)

Form Type

Rhea-AI Filing Summary

Castle Biosciences Chief Operating Officer Kristen M. Oelschlager reported open-market sales of a total of 8,586 shares of Common Stock on July 1, 2026, executed under a pre-arranged Rule 10b5-1 trading plan adopted on March 17, 2026.

The sales were completed in two weighted-average price transactions: 8,186 shares at $24.40 per share and 400 shares at $24.78 per share, across multiple trades within disclosed price ranges. Following these transactions, she holds 21,874 shares directly and 97,251 shares indirectly through the Fritz Shorter Trust, where she and her spouse serve as trustees and beneficiaries.

Insider Trade Summary 10b5-1

Net Seller: 8,586 shares ($209,650)

Net Sell 3 txns

Insider Oelschlager Kristen M

Role Chief Operating Officer

Sold 8,586 shs ($210K)

Type	Security	Shares	Price	Value
Sale	Common Stock	8,186	$24.40	$200K
Sale	Common Stock	400	$24.78	$10K
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 22,274 shares (Direct, null); Common Stock — 97,251 shares (Indirect, The Fritz Shorter Trust)

Footnotes (1)

These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person, on March 17, 2026. This transaction was executed in multiple trades at prices ranging from $23.73 to $24.72, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $24.77 to $24.79, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. Held by the Fritz Shorter Trust of which the Reporting Person and her spouse are the trustees and beneficiaries.

Key Figures

Shares sold: 8,586 shares Weighted-average sale price (8,186 shares): $24.40 per share Weighted-average sale price (400 shares): $24.78 per share +4 more

7 metrics

Shares sold 8,586 shares Total Common Stock sold on July 1, 2026

Weighted-average sale price (8,186 shares) $24.40 per share Open-market sale on July 1, 2026

Weighted-average sale price (400 shares) $24.78 per share Open-market sale on July 1, 2026

Direct holdings after sale 21,874 shares Common Stock directly owned after transactions

Indirect trust holdings 97,251 shares Held via the Fritz Shorter Trust

Price range first transaction $23.73–$24.72 Multiple trades comprising one reported sale

Price range second transaction $24.77–$24.79 Multiple trades comprising second reported sale

Key Terms

Rule 10b5-1 plan, weighted-average sale price, open-market sale, indirect ownership

4 terms

Rule 10b5-1 plan regulatory

"These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person"

A Rule 10b5-1 plan is a prearranged, written schedule that lets corporate insiders buy or sell company stock at set times or amounts, even if they later learn material nonpublic information. Think of it like setting an automatic thermostat for trades: it creates a clear record that trades were planned in advance, reducing the risk of insider-trading accusations and helping investors trust that insider transactions are routine rather than based on secret information.

weighted-average sale price financial

"The price reported above reflects the weighted-average sale price"

open-market sale financial

"transaction_action: open-market sale"

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

indirect ownership financial

"Held by the Fritz Shorter Trust of which the Reporting Person and her spouse are the trustees and beneficiaries"

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 07/06/2026 - 04:25 PM Accepted by SEC EDGAR 07/06/2026 - 04:24 PM

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Oelschlager Kristen M

(Last)

(First)

(Middle)

C/O CASTLE BIOSCIENCES, INC.

1500 W. PARKWOOD AVE SUITE 400

(Street)

FRIENDSWOOD

TEXAS

77546

(City)

(State)

(Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
CASTLE BIOSCIENCES INC [ CSTL ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director	10% Owner
X	Officer (give title below)	Other (specify below)
	Chief Operating Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
07/01/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	07/01/2026		S⁽¹⁾		8,186	D	$24.4⁽²⁾	22,274	D
Common Stock	07/01/2026		S⁽¹⁾		400	D	$24.78⁽³⁾	21,874	D
Common Stock								97,251	I	The Fritz Shorter Trust⁽⁴⁾

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

Explanation of Responses:

1. These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person, on March 17, 2026.

2. This transaction was executed in multiple trades at prices ranging from $23.73 to $24.72, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

3. This transaction was executed in multiple trades at prices ranging from $24.77 to $24.79, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

4. Held by the Fritz Shorter Trust of which the Reporting Person and her spouse are the trustees and beneficiaries.

Remarks:

	/s/ Frank Stokes, Attorney-in-fact	07/06/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR

FAQ

What insider transaction did CSTL’s COO report on this Form 4?

Castle Biosciences’ COO, Kristen M. Oelschlager, reported selling 8,586 shares of Common Stock in open-market transactions. These trades occurred on July 1, 2026 and were executed under a pre-arranged Rule 10b5-1 trading plan adopted earlier in March 2026.

At what prices did the CSTL COO sell Castle Biosciences shares?

The COO’s sales used weighted-average prices of $24.40 and $24.78 per share. Individual trades occurred within ranges of $23.73–$24.72 and $24.77–$24.79, with full trade and price details available to regulators and shareholders upon request.

How many Castle Biosciences shares does the COO hold after these sales?

After the reported transactions, the COO directly holds 21,874 Castle Biosciences shares. She also has indirect ownership of 97,251 shares through the Fritz Shorter Trust, where she and her spouse act as trustees and beneficiaries for the trust’s holdings.

What type of ownership does the Fritz Shorter Trust represent for CSTL shares?

The Fritz Shorter Trust represents indirect ownership of Castle Biosciences shares for the COO. The filing notes that she and her spouse are trustees and beneficiaries of the trust, which holds 97,251 Common Stock shares attributed as indirect holdings.