# EDGAR Filing Document

**Accession Number:** 0000879407
**File Stem:** 0000950170-25-109461
**Filing Date:** 2025-8
**Character Count:** 10748
**Document Hash:** 65ee5fd6feb4ce5a68d28701e2135999
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000950170-25-109461.hdr.sgml**: 20250815

**ACCESSION NUMBER**: 0000950170-25-109461

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

**PUBLIC DOCUMENT COUNT**: 2

**FILED AS OF DATE**: 20250815

**DATE AS OF CHANGE**: 20250815

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** ARROWHEAD PHARMACEUTICALS, INC.
- **CENTRAL INDEX KEY:** 0000879407
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 460408024
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 0930

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-48710
- **FILM NUMBER:** 251225742

**BUSINESS ADDRESS:**
- **STREET 1:** 177 E COLORADO BLVD
- **STREET 2:** SUITE 700
- **CITY:** PASADENA
- **STATE:** CA
- **ZIP:** 91105
- **BUSINESS PHONE:** 626-696-4702

**MAIL ADDRESS:**
- **STREET 1:** 177 E COLORADO BLVD
- **STREET 2:** SUITE 700
- **CITY:** PASADENA
- **STATE:** CA
- **ZIP:** 91105

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ARROWHEAD RESEARCH CORP
- **DATE OF NAME CHANGE:** 20040112

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** INTERACTIVE GROUP INC
- **DATE OF NAME CHANGE:** 20020509

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** INTERACTIVE INC
- **DATE OF NAME CHANGE:** 19940224
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Sarepta Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0000873303
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 930797222
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

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

**BUSINESS ADDRESS:**
- **STREET 1:** 215 FIRST STREET
- **STREET 2:** SUITE 415
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
- **BUSINESS PHONE:** 617-274-4000

**MAIL ADDRESS:**
- **STREET 1:** 215 FIRST STREET
- **STREET 2:** SUITE 415
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Sarepta Therapuetics, Inc.
- **DATE OF NAME CHANGE:** 20120712

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** AVI BIOPHARMA INC
- **DATE OF NAME CHANGE:** 19980930

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ANTIVIRALS INC
- **DATE OF NAME CHANGE:** 19970123

### Attached PDF Documents

**Attachment 1:** `ck0000000000-ex99_5.pdf`

_No text found in this document._

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

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**(Amendment No. 1)**

**ARROWHEAD PHARMACEUTICALS, INC.**

*(Name of Issuer)*

**Common stock, par value $0.001 per share (the "Common Stock")**

*(Title of Class of Securities)*

**04280A100**

*(CUSIP Number)*

**Cristin Rothfuss**<br>215 First Street<br>Cambridge MA 02142<br>(617) 274-4000

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

**08/13/2025**

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

| **CUSIP No.** | **04280A100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Sarepta Therapeutics, Inc.** | Name of reporting person<br>**Sarepta Therapeutics, Inc.** | |
| 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>**0.00** |
| 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>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**0.00** | Aggregate amount beneficially owned by each reporting person<br>**0.00** | |
| 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>**0.00%** | Percent of class represented by amount in Row (11)<br>**0.00%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**CO** | Type of Reporting Person (See Instructions)<br>**CO** | |

---

| **CUSIP No.** | **04280A100** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Sarepta Therapeutics Investments, Inc.** | Name of reporting person<br>**Sarepta Therapeutics Investments, Inc.** | |
| 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>**0.00** |
| 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>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**0.00** | Aggregate amount beneficially owned by each reporting person<br>**0.00** | |
| 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>**0.00%** | Percent of class represented by amount in Row (11)<br>**0.00%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**CO** | Type of Reporting Person (See Instructions)<br>**CO** | |

---

**Item 1. Security and Issuer**

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

**(b) Name of Issuer:**
ARROWHEAD PHARMACEUTICALS, INC.

**(c) Address of Issuer's Principal Executive Offices:**
177 E COLORADO BLVD, Suite 700, Pasadena, CA, 91105

This Amendment No. 1 to Schedule 13D (this "Amendment") amends the Schedule 13D (the "Original Schedule 13D") filed on February 14, 2025. Items 4, 5, 6 and 7 of the Original Schedule 13D are hereby amended and supplemented to the extent hereinafter expressly set forth. Except as amended hereby, the original disclosure set forth in the Original Schedule 13D shall remain unchanged. All capitalized terms used and not expressly defined herein have the respective meanings ascribed to such terms in the Original Schedule 13D.

**Item 4. Purpose of Transaction**

Item 4 of the Original Schedule 13D is hereby amended by adding the following:

On August 13, 2025, Sarepta Investments sold 9,265,312 shares of the Issuer's Common Stock at a price of $18.79 per share in a privately negotiated block trade pursuant to Rule 144 of the Securities Act of 1933, as amended (the "Secondary Sale").

Also on August 13, 2025, concurrently with the Secondary Sale, Sarepta, Sarepta Investments and the Issuer entered into a Letter Agreement (the "Letter Agreement") pursuant to which the Issuer agreed to redeem and acquire from Sarepta Investments 2,660,989 shares of the Issuer's Common Stock (the "Redemption") in satisfaction of the obligation of Sarepta to pay the Issuer $49,999,983.31 of the DM1 First Development Milestone Payment (as such term is defined in Section 8.3.1(a)(i) of the Collaboration Agreement).

The foregoing description of the Letter Agreement is not complete and is subject to and qualified in its entirety by reference to the full text of such agreement, which is attached as Exhibit 99.5 hereto and incorporated herein by reference.

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

**(a)**
Item 5 is hereby amended and restated in its entirety as follows:

On the date of this Amendment, the Reporting Persons beneficially own 0 shares of Common Stock, representing 0.0% of the Issuer's Common Stock outstanding.

**(b)**
0

**(c)**
Other than the sale of 9,265,312 shares of the Issuer's Common Stock pursuant to the Secondary Sale and 2,660,989 shares of the Issuer's Common Stock pursuant to the Redemption, in each case, at a price of $18.79 per share, as further described in Item 4, there have been no transactions in the securities of the Issuer effected by the Reporting Persons in the last 60 days.

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

Item 6 is hereby amended and restated in its entirety as follows:

Except as disclosed in the Original Schedule 13D and in Item 4 of this Amendment, there are no contracts, arrangements, understandings or relationships (legal or otherwise) to which any Reporting Person is a party with respect to the securities of the Issuer.

### 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:** Sarepta Therapeutics, Inc.

**Signature:** /s/ Ryan Wong

**Name/Title:** Ryan Wong, Executive Vice President, Chief Financial Officer

**Date:** 08/15/2025

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:** Sarepta Therapeutics Investments, Inc.

**Signature:** /s/ Joe Bratica

**Name/Title:** Joe Bratica, President

**Date:** 08/15/2025