SC 13G/A

NAMES OF REPORTING PERSONS

Perceptive Advisors LLC

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)

(a) ☐ (b) ☐

SEC USE ONLY

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware

SC 13G/A 1 d783014dsc13ga.htm SC 13G/A SC 13G/A

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 13G/A

Under the Securities Exchange Act of 1934

(Amendment No. 1)*

Arcellx, Inc.

(Name of Issuer)

Common Stock, par value $0.001 per share

(Title of Class of Securities)

03940C 100

(CUSIP Number)

December 31, 2023

(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)

*	The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 03940C 100

CUSIP No. 03940C 100

CUSIP No. 03940C 100

Item 1(a).

Name of Issuer:

Arcellx, Inc. (the “Issuer”)

Item 1(b).

Address of Issuer’s Principal Executive Offices:

25 West Watkins Mill Road, Suite A, Gaithersburg, MD 20878

Item 2(a).

Names of Persons Filing:

The names of the persons filing this report (collectively, the “Reporting Persons”) are:

Perceptive Advisors LLC (“Perceptive Advisors”)

Joseph Edelman (“Mr. Edelman”)

Perceptive Life Sciences Master Fund, Ltd. (the “Master Fund”)

Item 2(b).

Address of Principal Business Office or, if None, Residence:

The address of the principal business office of each of the Reporting Persons is:

51 Astor Place, 10th Floor

New York, NY 10003

Item 2(c).

Citizenship:

Perceptive Advisors is a Delaware limited liability company

Mr. Edelman is a United States citizen

The Master Fund is a Cayman Islands corporation

Item 2(d).

Title of Class of Securities:

Common Stock, par value $0.001 per share (“Common Stock”)

Item 2(e).

CUSIP Number:

03940C 100

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:

Not applicable.

Item 4.

Ownership.

The information required by this item with respect to each Reporting Person is set forth in Rows 5 through 9 and 11 of the cover page to this Schedule 13G. The ownership percentages reported are based on an aggregate of 51,928,729 shares of Common Stock, consisting of (i) 48,686,187 outstanding shares of Common Stock outstanding as of November 9, 2023, as reported in the Issuer’s Form 10-Q filed with the Securities and Exchange Commission (the “SEC”) on November 13, 2023, and (ii) 3,242,542 shares of Common Stock issued on December 28, 2023, in connection with a certain purchase agreement, as reported in the Issuer’s Current Report on Form 10-K filed on December 28, 2023.

The Master Fund directly holds 4,544,809 shares of Common Stock. Perceptive Advisors serves as the investment manager to the Master Fund and may be deemed to beneficially own such shares. Mr. Edelman is the managing member of Perceptive Advisors and may be deemed to beneficially own such shares.

Item 5.

Ownership of Five Percent or Less of a Class.

If this statement is being filed to report the fact that as of the date hereof the Reporting Persons have ceased to be the beneficial owner of more than five percent of the class of securities, check the following ☐.

Item 6.

Ownership of More than Five 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.

Certification.

Not applicable.

SIGNATURE

After reasonable inquiry and to the best of its knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Date: February 14, 2024


PERCEPTIVE ADVISORS LLC

By:		/s/ Joseph Edelman
		Name: Joseph Edelman
		Title: Managing Member

/s/ Joseph Edelman
JOSEPH EDELMAN

PERCEPTIVE LIFE SCIENCES MASTER FUND, LTD.

By:		Perceptive Advisors LLC

By:		/s/ Joseph Edelman
		Name: Joseph Edelman
		Title: Managing Member

SEC Form SC 13G/A filed by Arcellx Inc. (Amendment)