Company: ARWR
Filing Date: 2025-03-07
Form Type: 424B7
Source: 0001193125-25-049889
Chunk: 0

Company: ARROWHEAD PHARMACEUTICALS, INC.
Filing Date: 2025-03-07
Form: 424B7
Chunk 0
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Filed Pursuant to Rule 424(b)(7)
Registration Statement No. 333-268665

PROSPECTUS SUPPLEMENT

(To Prospectus dated December 5, 2022)

11,926,301 Shares

Common Stock

Pursuant to this prospectus
supplement, the selling stockholder identified herein (the “Selling Stockholder”) is offering on a resale basis an aggregate of 11,926,301 shares (the “Shares”) of common stock, par value $0.001 per share, of Arrowhead
Pharmaceuticals, Inc. (“Arrowhead,” “we,” “our” or the “Company”), a Delaware corporation. The Shares were acquired by the Selling Stockholder pursuant to a stock purchase agreement by and among the
Company and the Selling Stockholder, dated November 25, 2024 (the “Purchase Agreement”). We are registering the resale of the Shares covered by this prospectus supplement as required by an investor rights agreement by and among the
Company and the Selling Stockholder, dated February 7, 2025 (the “Investor Rights Agreement”).

We will not receive any of the proceeds
from sales by the Selling Stockholder of the Shares.

The Selling Stockholder may sell or otherwise dispose of the Shares covered by this prospectus
supplement in a number of different ways and at varying prices. However, our registration of the Shares does not mean that the Selling Stockholder will offer or sell any of the Shares. We provide more information about how the Selling Stockholder
may sell or otherwise dispose of the Shares covered by this prospectus supplement in the section entitled “Plan of Distribution” on page S-8. Discounts, concessions, commissions and similar selling expenses attributable to the sale
of the Shares covered by this prospectus supplement will be borne by the Selling Stockholder. We will pay all expenses (other than discounts, concessions, commissions and similar selling expenses) relating to the registration of the Shares with the
Securities and Exchange Commission (the “SEC”).

Our common stock is listed on The Nasdaq Global Select Market under the symbol
“ARWR.” On March 4, 2025, the last reported sale price of our common stock on The Nasdaq Global Select Market was $17.11 per share.

Investing in our securities involves a high degree of risk. Please read “Risk Factors” beginning on page S-5of this prospectus supplement and in the documents incorporated by reference or deemed to be incorporated by