Vanguard Realignment: Arcellx (ACLX) Beneficial Ownership Reported as 0%

Rhea-AI Filing Summary

Arcellx Inc Schedule 13G/A: The Vanguard Group filed Amendment No. 2 reporting 0 shares beneficially owned of Arcellx common stock following an internal realignment. The filing states certain Vanguard subsidiaries will report separately in reliance on SEC Release No. 34-39538 and that Vanguard no longer is deemed to beneficially own those securities. The amendment is dated 03/26/2026 and references the realignment on 01/12/2026.

Insights

Institutional Ownership Analyst

Vanguard disaggregated holdings; reported zero beneficial ownership for ACLX.

The amendment explains an internal realignment effective 01/12/2026 that caused certain subsidiaries or business divisions to report beneficial ownership separately under SEC Release No. 34-39538. The filing lists 0 shares and 0% ownership for The Vanguard Group.

This is an administrative disclosure of reporting structure rather than a market transaction; subsequent separate filings by Vanguard subsidiaries may show where holdings reside.

Securities Compliance Counsel

Amendment aligns reporting with SEC disaggregation guidance; no indication of a sale.

The text cites the release that permits separate reporting by subsidiaries and states Vanguard no longer is deemed to beneficially own the relevant securities. The signature block is by Head of Global Fund Administration dated 03/26/2026.

Regulatory focus should be on follow-up disclosures from the named subsidiaries or business divisions to trace actual beneficial holders.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 2)

Arcellx Inc

(Name of Issuer)

Common Stock

(Title of Class of Securities)

(CUSIP Number)

03/13/2026

(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 No.

1

Names of Reporting Persons

The Vanguard Group

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

PENNSYLVANIA

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

0.00

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)

0 %

12

Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person: On January 12, 2026, The Vanguard Group, Inc. went through an internal realignment. In accordance with SEC Release No. 34-39538 (January 12, 1998), certain subsidiaries or business divisions of subsidiaries of The Vanguard Group, Inc., that formerly had, or were deemed to have, beneficial ownership with The Vanguard Group, Inc., will report beneficial ownership separately (on a disaggregated basis) from The Vanguard Group, Inc. in reliance on such release. These subsidiaries and/or business divisions pursue the same investment strategies as previously pursued by The Vanguard Group, Inc. prior to the realignment. Further in accordance with SEC Release No. 34-39538 (January 12, 1998), The Vanguard Group, Inc. no longer has, or is deemed to have, beneficial ownership over securities beneficially owned by such subsidiaries and/or business divisions.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Arcellx Inc
(b)	Address of issuer's principal executive offices: 25 West Watkins Mill Road, Suite A, Gaithersburg, MD, 20878
Item 2.
(a)	Name of person filing: The Vanguard Group
(b)	Address or principal business office or, if none, residence: 100 Vanguard Blvd.,, Malvern, PA, 19355
(c)	Citizenship: PA
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.:
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: 0
(b)	Percent of class: 0 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 0
	(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.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. The Vanguard Group, including investment companies registered under the Investment Company Act of 1940 and other managed accounts, have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the securities reported herein.No one other person's interest in the securities reported herein is more than 5%.
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.

The Vanguard Group

Signature:	Ashley Grim
Name/Title:	Head of Global Fund Administration
Date:	03/26/2026

FAQ

What does the ACLX Schedule 13G/A filed by The Vanguard Group state?

It states The Vanguard Group reports 0 beneficially owned shares of Arcellx common stock and 0% ownership after an internal realignment on 01/12/2026. The filing cites SEC Release No. 34-39538 for disaggregated reporting.

Why does Vanguard report zero ownership for ACLX on this amendment?

Vanguard says an internal realignment caused certain subsidiaries to report separately in reliance on SEC Release No. 34-39538. As a result, The Vanguard Group no longer is deemed to beneficially own the securities previously reported under its umbrella.

Does the filing indicate Vanguard sold Arcellx (ACLX) shares?

No. The amendment explains a reporting change due to internal realignment and disaggregation under SEC Release No. 34-39538; it does not state any sale or transfer of shares by Vanguard in this excerpt.

Who signed the ACLX Schedule 13G/A amendment for Vanguard and when?

The filing is signed by Ashley Grim, Head of Global Fund Administration, on 03/26/2026. The signature attests to the amended beneficial ownership statement provided in the filing.

Will other Vanguard filings show who now reports ownership of ACLX?

Possibly. The amendment states certain Vanguard subsidiaries or business divisions will report separately; follow-up Schedule 13G/A or 13D/13G filings by those entities may disclose their respective beneficial ownership amounts.