Castle Biosciences: Principal reports 4.9% stake

The reported 4.9% position falls within the stated ownership category of 5% or less.

Rhea-AI Filing Summary

Castle Biosciences Inc. (CSTL) common stock was the subject of an ownership report by Principal Global Investors, which reported beneficial ownership of 1,500,897 shares, or 4.9% of the class, as of September 30, 2026. Principal Global Investors reported shared voting and dispositive power over those shares and no sole voting or dispositive power. J. Markham Penrod, Chief Compliance Officer - North America, Principal Asset Management, signed the amendment.

Key Figures

Beneficial ownership: 1,500,897 shares Percent of class: 4.9% Shared voting power: 1,500,897 shares +1 more

4 metrics

Beneficial ownership 1,500,897 shares Principal Global Investors; as of September 30, 2026

Percent of class 4.9% Principal Global Investors; as of September 30, 2026

Shared voting power 1,500,897 shares Principal Global Investors

Shared dispositive power 1,500,897 shares Principal Global Investors

Key Terms

beneficially owned, Shared Voting Power, Shared Dispositive Power

3 terms

beneficially owned financial

"Amount beneficially owned: 1,500,897"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

Shared Voting Power financial

"Shared Voting Power 1,500,897.00"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

Shared Dispositive Power financial

"Shared Dispositive Power 1,500,897.00"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many CSTL shares did Principal Global Investors report owning?

Principal Global Investors reported beneficial ownership of 1,500,897 shares, or 4.9% of the class, as of September 30, 2026.

What voting and disposition authority did Principal Global Investors report for CSTL shares?

Principal Global Investors reported shared voting power and shared dispositive power over 1,500,897 shares, with no sole voting or dispositive power.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 10/29/2026 - 10:32 AM EDT Accepted by SEC EDGAR 10/29/2026 - 10:32 AM EDT Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

CASTLE BIOSCIENCES INC

(Name of Issuer)

Common Stock, $0.001 par value per share

(Title of Class of Securities)

14843C105

(CUSIP Number)

09/30/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 14843C105

1

Names of Reporting Persons

PRINCIPAL GLOBAL INVESTORS

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,500,897.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,500,897.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,500,897.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

4.9 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: CASTLE BIOSCIENCES INC
(b)	Address of issuer's principal executive offices: 1500 W. PARKWOOD AVE., SUITE 400, FRIENDSWOOD, TEXAS 77546
Item 2.
(a)	Name of person filing: PRINCIPAL GLOBAL INVESTORS
(b)	Address or principal business office or, if none, residence: 711 HIGH STREET DES MOINES, Iowa 50392-0300
(c)	Citizenship: PRINCIPAL GLOBAL INVESTORS - DELAWARE
(d)	Title of class of securities: Common Stock, $0.001 par value per share
(e)	CUSIP No.: 14843C105
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 1,500,897
(b)	Percent of class: 4.9 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: PRINCIPAL GLOBAL INVESTORS - 0
	(ii) Shared power to vote or to direct the vote: PRINCIPAL GLOBAL INVESTORS - 1,500,897
	(iii) Sole power to dispose or to direct the disposition of: PRINCIPAL GLOBAL INVESTORS - 0
	(iv) Shared power to dispose or to direct the disposition of: PRINCIPAL GLOBAL INVESTORS - 1,500,897
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

PRINCIPAL GLOBAL INVESTORS

Signature:	/s/ J. Markham Penrod
Name/Title:	J. Markham Penrod, Chief Compliance Officer - North America, Principal Asset Management
Date:	10/28/2026