# EDGAR Filing Document

**Accession Number:** 0001629794
**File Stem:** 0001072613-25-000617
**Filing Date:** 2025-8
**Character Count:** 33675
**Document Hash:** 59da82efeed69a7b3473a92e7a9b436c
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001072613-25-000617.hdr.sgml**: 20250814

**ACCESSION NUMBER**: 0001072613-25-000617

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D/A

**PUBLIC DOCUMENT COUNT**: 4

**FILED AS OF DATE**: 20250814

**DATE AS OF CHANGE**: 20250814

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Arcellx, Inc.
- **CENTRAL INDEX KEY:** 0001786205
- **STANDARD INDUSTRIAL CLASSIFICATION:** BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 472855917
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-93375
- **FILM NUMBER:** 251222155

**BUSINESS ADDRESS:**
- **STREET 1:** 800 BRIDGE PARKWAY
- **CITY:** REDWOOD CITY
- **STATE:** CA
- **ZIP:** 94065
- **BUSINESS PHONE:** 240-327-0603

**MAIL ADDRESS:**
- **STREET 1:** 800 BRIDGE PARKWAY
- **CITY:** REDWOOD CITY
- **STATE:** CA
- **ZIP:** 94065
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** New Enterprise Associates 15, L.P.
- **CENTRAL INDEX KEY:** 0001629794

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A

**BUSINESS ADDRESS:**
- **STREET 1:** 1954 GREENSPRING DRIVE, SUITE 600
- **CITY:** TIMONIUM
- **STATE:** MD
- **ZIP:** 21093
- **BUSINESS PHONE:** 410-842-4000

**MAIL ADDRESS:**
- **STREET 1:** 1954 GREENSPRING DRIVE, SUITE 600
- **CITY:** TIMONIUM
- **STATE:** MD
- **ZIP:** 21093

## Ex-1

**<u>EXHIBIT 1</u>**

**AGREEMENT**

Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, the undersigned hereby agree that only one statement containing the information required by Schedule 13D need be filed with respect to the ownership by each of the undersigned of shares of stock of Arcellx, Inc.

EXECUTED this 14<sup>th</sup> day of August, 2025.

NEW ENTERPRISE ASSOCIATES 15, L.P.

By: NEA PARTNERS 15, L.P. General Partner

By: NEA 15 GP, LLC General Partner

&nbsp;&nbsp;&nbsp;&nbsp;By: <u>\*</u> 

Anthony A. Florence, Jr.

Managing Partner and Co-Chief Executive Officer

&nbsp;&nbsp;&nbsp;&nbsp;By: <u>\*</u> 

Mohamad Makhzoumi

Managing Partner and Co-Chief Executive Officer

NEA PARTNERS 15, L.P.

By: NEA 15 GP, LLC<br> General Partner

&nbsp;&nbsp;&nbsp;&nbsp;By: <u>\*</u> 

Anthony A. Florence, Jr.

Managing Partner and Co-Chief Executive Officer

&nbsp;&nbsp;&nbsp;&nbsp;By: <u>\*</u> 

Mohamad Makhzoumi

Managing Partner and Co-Chief Executive Officer

NEA 15 GP, LLC

By: <u>\*</u> 

Anthony A. Florence, Jr.

Managing Partner and Co-Chief Executive Officer

By: <u>\*</u> 

Mohamad Makhzoumi

Managing Partner and Co-Chief Executive Officer

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<u>\*</u> 

Forest Baskett

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<u>\*</u> 

Anthony A. Florence, Jr.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<u>\*</u> 

Mohamad H. Makhzoumi

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<u>\*</u> 

Scott D. Sandell

<u>\*/s/ Zachary Bambach</u> 

Zachary Bambach

As attorney-in-fact

This Agreement relating to Schedule 13D was executed by Zachary Bambach on behalf of the individuals listed above pursuant to a Power of Attorney, a copy of which is attached hereto as Exhibit 2.

## Ex-2

**<u>EXHIBIT 2</u>**

**SCHEDULE A**

Transactions during the past 60 days

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
| | | | | | &nbsp;&nbsp;**Price Range** | &nbsp;&nbsp;**Price Range** |
| <br>&nbsp;&nbsp;**Name** | <br>&nbsp;&nbsp;**Transaction Date** | <br>&nbsp;&nbsp;**Nature of Transaction** | <br>&nbsp;&nbsp;**Quantity** | <br>&nbsp;&nbsp;**Weighted Average Price Per Share\*** | &nbsp;&nbsp;**Minimum** | &nbsp;&nbsp;**Maximum** |
| &nbsp;&nbsp;Mohamad H. Makhzoumi and Katherine Makhzoumi, as Trustees of the Makhzoumi Family Trust dated February 11, 2016 (the "Makhzoumi Family Trust") | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;400 | &nbsp;&nbsp;$67.2400 | &nbsp;&nbsp;$67.24 | &nbsp;&nbsp;$67.24 |
| &nbsp;&nbsp;Makhzoumi Family Trust | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;2222 | &nbsp;&nbsp;$68.7439 | &nbsp;&nbsp;$68.32 | &nbsp;&nbsp;$69.13 |
| &nbsp;&nbsp;Makhzoumi Family Trust | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;5312 | &nbsp;&nbsp;$70.5407 | &nbsp;&nbsp;$69.83 | &nbsp;&nbsp;$70.82 |
| &nbsp;&nbsp;Makhzoumi Family Trust | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;1623 | &nbsp;&nbsp;$70.9653 | &nbsp;&nbsp;$70.84 | &nbsp;&nbsp;$71.13 |
| &nbsp;&nbsp;Baskett-McKay Family Trust dtd 3/12/2014 | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;2334 | &nbsp;&nbsp;$70.7857 | &nbsp;&nbsp;$70.22 | &nbsp;&nbsp;$71.14 |
| &nbsp;&nbsp;Baskett-McKay Family Trust dtd 3/12/2014 | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;5432 | &nbsp;&nbsp;$71.6708 | &nbsp;&nbsp;$71.22 | &nbsp;&nbsp;$72.13 |
| &nbsp;&nbsp;Baskett-McKay Family Trust dtd 3/12/2014 | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;1370 | &nbsp;&nbsp;$72.6699 | &nbsp;&nbsp;$72.41 | &nbsp;&nbsp;$72.83 |
| &nbsp;&nbsp;Anthony A. Florence, Jr. | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;4271 | &nbsp;&nbsp;$70.8366 | &nbsp;&nbsp;$70.70 | &nbsp;&nbsp;$71.64 |
| &nbsp;&nbsp;Anthony A. Florence, Jr. | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;5187 | &nbsp;&nbsp;$72.5035 | &nbsp;&nbsp;$71.71 | &nbsp;&nbsp;$72.64 |
| &nbsp;&nbsp;New Enterprise Associates, LLC | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;6.3968 | &nbsp;&nbsp;$70.8032 | &nbsp;&nbsp;$70.09 | &nbsp;&nbsp;$71.04 |
| &nbsp;&nbsp;New Enterprise Associates, LLC | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;32.4242 | &nbsp;&nbsp;$71.6509 | &nbsp;&nbsp;$71.095 | &nbsp;&nbsp;$72.05 |
| &nbsp;&nbsp;New Enterprise Associates, LLC | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;9.1790 | &nbsp;&nbsp;$72.6636 | &nbsp;&nbsp;$72.27 | &nbsp;&nbsp;$72.94 |
| &nbsp;&nbsp;NEA Investment Holdings CF, LLC | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;1375.438 | &nbsp;&nbsp;$70.8032 | &nbsp;&nbsp;$70.09 | &nbsp;&nbsp;$71.04 |
| &nbsp;&nbsp;NEA Investment Holdings CF, LLC | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;6971.983 | &nbsp;&nbsp;$71.6509 | &nbsp;&nbsp;$71.095 | &nbsp;&nbsp;$72.05 |
| &nbsp;&nbsp;NEA Investment Holdings CF, LLC | &nbsp;&nbsp;August 13, 2025 | &nbsp;&nbsp;Open Market Sale | &nbsp;&nbsp;1973.578 | &nbsp;&nbsp;$72.6636 | &nbsp;&nbsp;$72.27 | &nbsp;&nbsp;$72.94 |

---

\* The Reporting Persons undertake to provide to the SEC staff, upon request, full information regarding the number of shares purchased at each price within the ranges set forth in the table above.

## Ex-3

**<u>EXHIBIT 3</u>**

**POWER OF ATTORNEY**

KNOW ALL MEN BY THESE PRESENTS, that the undersigned hereby constitutes and appoints Zachary Bambach, Nicole Hatcher and Stephanie Brecher, and each of them, with full power to act without the others, his or her true and lawful attorney-in-fact, with full power of substitution, to sign any and all instruments, certificates and documents that may be necessary, desirable or appropriate to be executed on behalf of himself as an individual or in his or her capacity as a direct or indirect general partner, director, officer or manager of any partnership, corporation or limited liability company, pursuant to section 13 or 16 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and any and all regulations promulgated thereunder, including, without limitation, Forms 3, 4 and 5 and Schedules 13D and 13G (and any amendments thereto), and to file the same, with all exhibits thereto, and any other documents in connection therewith, with the Securities and Exchange Commission (the "SEC"), including, but not limited to, signing a Form ID for and on behalf of the undersigned and filing such Form ID with the SEC, and with any other entity when and if such is mandated by the Exchange Act or by the Financial Industry Regulatory Authority, granting unto said attorney-in-fact full power and authority to do and perform each and every act and thing necessary, desirable or appropriate, fully to all intents and purposes as he or she might or could do in person, thereby ratifying and confirming all that said attorney-in-fact, or his or her substitutes, may lawfully do or cause to be done by virtue hereof. This power of attorney is perpetual, unless revoked by the undersigned in a signed writing delivered to each of the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, this Power of Attorney has been signed as of the 29th day of February, 2024.

---

| |
|:---|
| /s/ Peter J. Barris |
| Peter J. Barris |
| /s/ Forest Baskett |
| Forest Baskett |
| /s/ Ali Behbahani |
| Ali Behbahani |
| /s/ Ronald D. Bernal |
| Ronald D. Bernal |
| /s/ Ann Bordetsky |
| Ann Bordetsky |
| /s/ Carmen Chang |
| Carmen Chang |
| /s/ Philip Chopin |
| Philip Chopin |
| /s/ Anthony A. Florence, Jr. |
| Anthony A. Florence, Jr. |
| /s/ Jonathan Golden |
| Jonathan Golden |
| /s/ Scott Gottlieb |
| Scott Gottlieb |
| /s/ Mark Hawkins |
| Mark Hawkins |
| /s/ Jeffrey R. Immelt |
| Jeffrey R. Immelt |
| /s/ Aaron Jacobson |
| Aaron Jacobson |
| /s/ Patrick J. Kerins |
| Patrick J. Kerins |
| /s/ Hilarie Koplow-McAdams |
| Hilarie Koplow-McAdams |
| /s/ Vanessa Larco |
| Vanessa Larco |
| /s/ Julio C. Lopez |
| Julio C. Lopez |
| /s/ Tiffany Le |
| Tiffany Le |
| /s/ Mohamad H. Makhzoumi |
| Mohamad H. Makhzoumi |
| /s/ Edward T. Mathers |
| Edward T. Mathers |
| /s/ Gregory Papadopoulos |
| Gregory Papadopoulos |
| /s/ Kavita Patel |
| Kavita Patel |
| /s/ Scott D. Sandell |
| Scott D. Sandell |
| /s/ A. Brooke Seawell |
| A. Brooke Seawell |
| /s/ Peter Sonsini |
| Peter Sonsini |
| /s/ Melissa Taunton |
| Melissa Taunton |
| /s/ Paul E. Walker |
| Paul E. Walker |
| /s/ Rick Yang |
| Rick Yang |

---

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

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**(Amendment No. 4)**

**Arcellx, Inc.**

*(Name of Issuer)*

**Common Stock $0.001 par value per share**

*(Title of Class of Securities)*

**03940C100**

*(CUSIP Number)*

**Stephanie Brecher**<br>New Enterprise Associates<br>1954 Greenspring Drive, Suite 600<br>Timonium MD 21093<br>(410)842-4000

*(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)*

**08/12/2025**

*(Date of Event Which Requires Filing of this Statement)*

| **CUSIP No.** | **03940C100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**New Enterprise Associates 15, L.P.** | Name of reporting person<br>**New Enterprise Associates 15, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**3045262.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**3045262.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**3045262.00** | Aggregate amount beneficially owned by each reporting person<br>**3045262.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**5.49%** | Percent of class represented by amount in Row (11)<br>**5.49%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

| **CUSIP No.** | **03940C100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**NEA Partners 15, L.P.** | Name of reporting person<br>**NEA Partners 15, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**3045262.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**3045262.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**3045262.00** | Aggregate amount beneficially owned by each reporting person<br>**3045262.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**5.49%** | Percent of class represented by amount in Row (11)<br>**5.49%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

| **CUSIP No.** | **03940C100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**NEA 15 GP, LLC** | Name of reporting person<br>**NEA 15 GP, LLC** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**3045262.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**3045262.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**3045262.00** | Aggregate amount beneficially owned by each reporting person<br>**3045262.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**5.49%** | Percent of class represented by amount in Row (11)<br>**5.49%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**OO** | Type of Reporting Person (See Instructions)<br>**OO** | |

---

| **CUSIP No.** | **03940C100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Forest Baskett** | Name of reporting person<br>**Forest Baskett** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**X1** | Citizenship or place of organization<br>**X1** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**3045262.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**3045262.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**3045262.00** | Aggregate amount beneficially owned by each reporting person<br>**3045262.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**5.49%** | Percent of class represented by amount in Row (11)<br>**5.49%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

| **CUSIP No.** | **03940C100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Anthony A. Florence, Jr.** | Name of reporting person<br>**Anthony A. Florence, Jr.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**X1** | Citizenship or place of organization<br>**X1** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**3045262.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**3045262.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**3045262.00** | Aggregate amount beneficially owned by each reporting person<br>**3045262.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**5.49%** | Percent of class represented by amount in Row (11)<br>**5.49%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

| **CUSIP No.** | **03940C100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Mohamad H. Makhzoumi** | Name of reporting person<br>**Mohamad H. Makhzoumi** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**X1** | Citizenship or place of organization<br>**X1** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**3045262.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**3045262.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**3045262.00** | Aggregate amount beneficially owned by each reporting person<br>**3045262.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**5.49%** | Percent of class represented by amount in Row (11)<br>**5.49%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

| **CUSIP No.** | **03940C100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Scott D. Sandell** | Name of reporting person<br>**Scott D. Sandell** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**X1** | Citizenship or place of organization<br>**X1** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**7910.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**3047450.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**7910.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**3047450.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**3055360.00** | Aggregate amount beneficially owned by each reporting person<br>**3055360.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**5.51%** | Percent of class represented by amount in Row (11)<br>**5.51%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Stock $0.001 par value per share

**(b) Name of Issuer:**
Arcellx, Inc.

**(c) Address of Issuer's Principal Executive Offices:**
800 Bridge Parkway, Redwood City, CA, 94065

This Amendment No. 4 ("Amendment No. 4") to Schedule 13D amends and supplements the Schedule 13D originally filed on February 17, 2022 (the "Schedule 13D"), Amendment No. 1 thereto filed on January 24, 2023 ("Amendment No. 1"), Amendment No. 2 thereto filed on June 23, 2023 ("Amendment No. 2") and Amendment No. 3 thereto filed on May 12, 2025 ("Amendment No. 3"), relating to the Common Stock of the Issuer.

Certain terms used but not defined in this Amendment No. 4 have the meanings assigned thereto in the Schedule 13D (and Amendment No. 1, Amendment No. 2 and Amendment No. 3 thereto). Except as specifically provided herein, this Amendment No. 4 does not modify any of the information previously reported on the Schedule 13D (and Amendment No. 1, Amendment No. 2 and Amendment No. 3 thereto).

**Item 4. Purpose of Transaction**

NEA 15 acquired the NEA 15 Shares for investment purposes. Depending on market conditions, its continuing evaluation of the business and prospects of the Issuer and other factors, NEA 15 and the other Reporting Persons may dispose of or acquire additional shares of the Issuer. Except as set forth above, none of the Reporting Persons has any present plans which relate to or would result in:

(a) The acquisition by any person of additional securities of the Issuer, or the disposition of securities of the Issuer;

(b) An extraordinary corporate transaction, such as a merger, reorganization or liquidation, involving the Issuer or any of its subsidiaries;

(c) A sale or transfer of a material amount of assets of the Issuer or any of its subsidiaries;

(d) Any change in the present board of directors or management of the Issuer, including any plans or proposals to change the number or term of directors or to fill any existing vacancies on the board;

(e) Any material change in the present capitalization or dividend policy of the Issuer;

(f) Any other material change in the Issuer's business or corporate structure;

(g) Changes in the Issuer's charter, bylaws or instruments corresponding thereto or other actions which may impede the acquisition of control of the Issuer by any person;

(h) Causing a class of securities of the Issuer to be delisted from a national securities exchange or to cease to be authorized to be quoted in an inter-dealer quotation system of a registered national securities association;

(i) A class of equity securities of the Issuer becoming eligible for termination of registration pursuant to Section 12(g)(4) of the Securities Exchange Act of 1934; or

(j) Any action similar to any of those enumerated above.

**Item 5. Interest in Securities of the Issuer**

**(a)**
NEA 15 is the record owner of the NEA 15 Shares (as defined below). As the general partner of NEA 15, NEA Partners 15 may be deemed to own beneficially the NEA 15 Shares. As the sole general partner of NEA Partners 15, NEA 15 LLC may be deemed to own beneficially the NEA 15 Shares. As members of NEA 15 LLC, each of the Managers may be deemed to own beneficially the NEA 15 Shares.

Each Reporting Person disclaims beneficial ownership of the NEA 15 Shares other than those shares which such person owns of record.

The percentage of outstanding Common Stock of the Issuer which may be deemed to be beneficially owned by each Reporting Person is set forth on Line 13 of such Reporting Person's cover sheet. Such percentage was calculated based on 55,458,912 shares of Common Stock reported by the Issuer to be outstanding as of August 1, 2025, on the Issuer's Form 10-Q filed with the Securities and Exchange Commission on August 7, 2025.

**(b)**
Regarding the number of shares as to which such person has:
(i) sole power to vote or to direct the vote: See line 7 of cover sheets
(ii) shared power to vote or to direct the vote: See line 8 of cover sheets
(iii) sole power to dispose or to direct the disposition: See line 9 of cover sheets
(iv) shared power to dispose or to direct the disposition: See line 10 of cover sheets.

**(c)**
On August 12, 2025, NEA 15 made a pro rata distribution of 700,000 shares of Common Stock of the Issuer to its general partner and its limited partners for no consideration (the "NEA 15 Distribution"). NEA Partners 15 acquired 168,217 shares of Common Stock of the Issuer as a result of the NEA 15 Distribution and, subsequent to the NEA 15 Distribution, on August 12, 2025, made a pro rata distribution of 168,217 shares of Common Stock of the Issuer to its limited partners for no consideration (the "NEA Partners 15 Distribution"). NEA 15 now holds a total of 3,045,262 shares of Common Stock of the Issuer (the "NEA 15 Shares").

On August 12, 2025, Baskett, Florence, Makhzoumi and Sandell received shares in the NEA Partners 15 Distribution (either directly or indirectly via entities or trusts for which they may be deemed to have a beneficial ownership interest), certain of which shares were sold on August 13, 2025. Schedule A attached hereto as Exhibit 2 describes all transactions in the Issuer's Common Stock that were effected during the past 60 days by the Reporting Persons.

As of August 14, 2025, the Blue Mountain Trust, dated April 29, 2019 (the "Blue Mountain Trust") is the record owner of 7,910 shares of Common Stock (the "Blue Mountain Trust Shares"). As trustee of the Blue Mountain Trust, Sandell may be deemed to own beneficially the Blue Mountain Trust Shares. As of August 14, 2025, Sandell may be deemed to own beneficially the 1,094 shares of Common Stock held by the Scott Sandell Rising River Trust, dated December 20, 2012 and the 1,094 shares of Common Stock held by the Jennifer Ayer Sandell Rising River Trust, dated December 20, 2012.

**Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.**

Not applicable.

### 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.

**Reporting Person:** New Enterprise Associates 15, L.P.

**Signature:** /s/ Zachary Bambach

**Name/Title:** Zachary Bambach as attorney-in-fact for Anthony A. Florence Jr., Managing Partner and Co-Chief Executive Officer

**Date:** 08/14/2025

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.

**Reporting Person:** NEA Partners 15, L.P.

**Signature:** /s/ Zachary Bambach

**Name/Title:** Zachary Bambach as attorney-in-fact for Anthony A. Florence Jr., Managing Partner and Co-Chief Executive Officer

**Date:** 08/14/2025

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.

**Reporting Person:** NEA 15 GP, LLC

**Signature:** /s/ Zachary Bambach

**Name/Title:** Zachary Bambach as attorney-in-fact for Anthony A. Florence Jr., Managing Partner and Co-Chief Executive Officer

**Date:** 08/14/2025

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.

**Reporting Person:** Forest Baskett

**Signature:** /s/ Zachary Bambach

**Name/Title:** Zachary Bambach as attorney-in-fact for Forest Baskett

**Date:** 08/14/2025

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.

**Reporting Person:** Anthony A. Florence, Jr.

**Signature:** /s/ Zachary Bambach

**Name/Title:** Zachary Bambach as attorney-in-fact for Anthony A. Florence Jr.

**Date:** 08/14/2025

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.

**Reporting Person:** Mohamad H. Makhzoumi

**Signature:** /s/ Zachary Bambach

**Name/Title:** Zachary Bambach as attorney-in-fact for Mohamad H. Makhzoumi

**Date:** 08/14/2025

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.

**Reporting Person:** Scott D. Sandell

**Signature:** /s/ Zachary Bambach

**Name/Title:** Zachary Bambach as attorney-in-fact for Scott D. Sandell

**Date:** 08/14/2025