[SCHEDULE 13D/A] Arrowhead Research Corporation SEC Filing

Rhea-AI Filing Summary

Amendment No. 1 to Schedule 13D updates prior disclosure that Sarepta Therapeutics, Inc. and its affiliate Sarepta Therapeutics Investments, Inc. no longer hold any shares of Arrowhead Pharmaceuticals, Inc. The amendment states that on August 13, 2025 Sarepta Investments sold 9,265,312 shares in a privately negotiated block trade at $18.79 per share and, concurrently, Sarepta Investments sold an additional 2,660,989 shares back to Arrowhead in a redemption under a Letter Agreement to satisfy a $49,999,983.31 milestone payment obligation. After these transactions the reporting persons beneficially own 0 shares (0.0% of the class) and ceased to be beneficial owners of more than 5% of Arrowhead's common stock.

Positive

• Milestone payment satisfied via redemption of 2,660,989 shares for $49,999,983.31, resolving a contractual obligation
• Transparent disclosure of both the privately negotiated block trade and the Letter Agreement with the issuer, with the Letter Agreement filed as an exhibit

Negative

• Former >5% holder exited, as reporting persons now beneficially own 0 shares (0.0%), which is a material change in ownership
• Large block sale of 9,265,312 shares could have impacted market liquidity and pricing at the time of the transaction

Insights

Financial Analyst

TL;DR: Large block sale and issuer redemption eliminated a >5% holder; proceeds and milestone-driven redemption materially changed ownership.

The filing discloses a significant secondary sale of 9.27 million shares and a concurrent issuer redemption of 2.66 million shares at $18.79 each. The redemption satisfied a nearly $50.0 million contractual milestone, reducing the reporting persons' stake to zero. For investors, the departure of a formerly >5% holder is material because it removes a concentrated shareholder and may alter future trading liquidity and shareholder composition. The transactions appear structured to monetize holdings and satisfy a contractual payment rather than represent smaller, incremental market sales.

Corporate Governance Expert

TL;DR: Ownership change is material to governance but the filing reports no continuing agreements affecting control.

The amendment affirms that, aside from the disclosed Letter Agreement and previously reported arrangements, there are no remaining contracts, arrangements or understandings between the reporting persons and the issuer regarding the issuer's securities. The reporting persons certify cessation of beneficial ownership above 5%, and the document attaches the Letter Agreement as an exhibit. From a governance perspective, removal of a >5% holder reduces potential activist or strategic influence, and the absence of remaining agreements limits governance implications arising from these parties.

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
215 First Street,
Cambridge, MA, 02142
(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)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on 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).

SCHEDULE 13D

CUSIP No. 04280A100

1

Name of reporting person

Sarepta Therapeutics, Inc.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0.00 %

14

Type of Reporting Person (See Instructions)

CO

SCHEDULE 13D

CUSIP No. 04280A100

1

Name of reporting person

Sarepta Therapeutics Investments, Inc.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0.00 %

14

Type of Reporting Person (See Instructions)

CO

SCHEDULE 13D

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, CALIFORNIA , 91105.
Item 1 Comment: 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.
(d)	Not applicable
(e)	The Reporting Persons ceased to be the beneficial owners of more than 5% of the shares of the Issuer's Common Stock as of August 13, 2025.
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.
Item 7.	Material to be Filed as Exhibits.
	Item 7 is hereby amended to include the following exhibit: Exhibit 99.5 Letter Agreement, dated as of August 13, 2025 among Arrowhead Pharmaceuticals, Inc., Sarepta Therapeutics, Inc. and Sarepta Therapeutics Investments, Inc.

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.

Sarepta Therapeutics, Inc.

Signature:	/s/ Ryan Wong
Name/Title:	Ryan Wong, Executive Vice President, Chief Financial Officer
Date:	08/15/2025

Sarepta Therapeutics Investments, Inc.

Signature:	/s/ Joe Bratica
Name/Title:	Joe Bratica, President
Date:	08/15/2025

FAQ

What did Sarepta Therapeutics (ARWR) disclose in this Schedule 13D/A?

The filing discloses that Sarepta Therapeutics and its affiliate sold 9,265,312 shares in a private block trade at $18.79 per share and that 2,660,989 shares were redeemed by Arrowhead to satisfy a $49,999,983.31 milestone payment, leaving the reporting persons with 0 shares (0.0%).

How many shares were sold and at what price?

Sarepta Investments sold 9,265,312 shares in a privately negotiated block trade at $18.79 per share.

What was the redemption and why did it occur?

Arrowhead agreed to redeem 2,660,989 shares from Sarepta Investments under a Letter Agreement to satisfy Sarepta's obligation to pay $49,999,983.31 as a DM1 development milestone.

Do the reporting persons retain any ownership in Arrowhead after the transactions?

No. The amendment states the reporting persons beneficially own 0 shares, representing 0.0% of Arrowhead's common stock.

Are there any remaining contracts or arrangements between Sarepta and Arrowhead regarding the securities?

The filing states that, except as disclosed in the Original Schedule 13D and this amendment (including the Letter Agreement), there are no contracts, arrangements, understandings or relationships concerning Arrowhead securities.