Arcellx (NASDAQ: ACLX) — T. Rowe Price reports 4.5% holding in 13G/A

Rhea-AI Filing Summary

Arcellx Inc. Schedule 13G/A discloses that T. Rowe Price Investment Management, Inc. beneficially owned 2,653,848 shares of Arcellx common stock, representing 4.5% of the class as of 02/28/2026. The filing states sole voting power of 2,503,059 shares and sole dispositive power of 2,647,494. Item 5 notes ownership of 5 percent or less of a class.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 3)

ARCELLX INC

(Name of Issuer)

COMMON STOCK

(Title of Class of Securities)

02/28/2026

(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)

SCHEDULE 13G

CUSIP Number(s):

1

Names of Reporting Persons

T. Rowe Price Investment Management, Inc.

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

MARYLAND

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 2,503,059.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 2,647,494.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,653,848.00

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)

4.5 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: ARCELLX INC
(b)	Address of issuer's principal executive offices: 800 BRIDGE PARKWAY, REDWOOD CITY, CA, 94065
Item 2.
(a)	Name of person filing: T. Rowe Price Investment Management, Inc.
(b)	Address or principal business office or, if none, residence: 1307 Point Street, Baltimore, MD 21231
(c)	Citizenship: Maryland
(d)	Title of class of securities: COMMON STOCK
(e)	CUSIP No.: 03940C100
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: 2653848
(b)	Percent of class: 4.5 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 2503059
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 2647494
	(iv) Shared power to dispose or to direct the disposition of: 0
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. T. Rowe Price Investment Management, Inc. hereby declares and affirms that the filing of Schedule 13G shall not be construed as an admission that Price Investment Management is the beneficial owner of the securities referred to, which beneficial ownership is expressly denied.

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.

T. Rowe Price Investment Management, Inc.

Signature:	Ellen York
Name/Title:	Vice President
Date:	03/06/2026

FAQ

What did T. Rowe Price report for ACLX in the Schedule 13G/A?

Direct answer: T. Rowe Price reported beneficial ownership of 2,653,848 shares (4.5%) of Arcellx common stock as of 02/28/2026. Context: The filing lists sole voting power of 2,503,059 and sole dispositive power of 2,647,494.

Does the filing indicate T. Rowe Price controls more than 5% of ACLX?

Direct answer: No, the filing indicates ownership of 4.5%, which is under 5 percent. Context: Item 5 expressly states "Ownership of 5 percent or less of a class," and the cover shows the 4.5% figure.

What powers over the shares does T. Rowe Price report for ACLX?

Direct answer: The filer reports sole voting power for 2,503,059 shares and sole dispositive power for 2,647,494 shares. Context: The filing shows no shared voting or dispositive power for these holdings.

What date is the ownership in the ACLX Schedule 13G/A measured as of?

Direct answer: The filing lists the measurement date as 02/28/2026. Context: The amendment header shows that date and the signature block is dated 03/06/2026, consistent with the Schedule 13G/A amendment timing.

Does the Schedule 13G/A imply beneficial ownership by an individual at T. Rowe Price?

Direct answer: No, the filer is listed as T. Rowe Price Investment Management, Inc., a Maryland entity, not an individual. Context: The filing includes a corporate signature by a Vice President, and it disclaims admission of beneficial ownership in the text.