Company: ARWR
Filing Date: 2025-12-11
Form Type: S-3ASR
Source: 0001193125-25-314755
Chunk: 32

Company: ARROWHEAD PHARMACEUTICALS, INC.
Filing Date: 2025-12-11
Form: S-3ASR
Chunk 32
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 our 2013                                                                                                        
 Incentive Plan (the “2013 Plan”), our 2021 Incentive Plan (the “2021 Plan”), our Inducement Plan (the “Inducement Plan”) and issued as inducement grants to new employees outside of our equity compensation plans 
 having a weighted average exercise price of $28.90 per share;                                                                                                                                                      |

| • |     | 5,810,351 restricted stock units granted and outstanding as of September 30, 2025 under the 2013 Plan, 2021      
 Plan, Inducement Plan and issued as inducement grants to new employees outside of our equity compensation plans; |

| • |     | 2,378,770 shares reserved for issuance under the 2021 Plan; |

| • |     | 255,244 shares reserved for issuance under the Inducement Plan; and |

| • |     | 917,441 shares of common stock issuable upon the exercise of outstanding            
 pre-funded warrants at an exercise price of $0.001 per share (which do not expire). |

S-5

RISK FACTORS

An investment in shares of our common stock involves a high degree of risk. Prior to making a decision about investing in shares of our common stock, you should carefully consider the risk factors described below and the risk factors discussed in the sections entitled “Risk Factors” contained in our most recent Annual Report on Form 10-K,Quarterly Reports in Form 10-Qsand our other filings with the SEC incorporated by reference in this prospectus supplement, together with all of the other information contained in this prospectus supplement. Additional risks and uncertainties not presently known to us, or that we currently view as immaterial, may also impair our business. Our business, financial condition and results of operations could be materially and adversely affected as a result of these risks. This could cause the trading price of our common stock to decline, resulting in a loss of all or part of your investment.

Risks Related to this Offering

We will have broad discretion in the use of the net proceeds from this offering and, despite our efforts, we may use the net proceeds in a manner that does not increase the value of your investment.

We currently intend to use the net proceeds from this offering for general corporate purposes, including working capital, capital expenditures,
research and development expenditures and clinical trial expenditures. A portion of the net proceeds may also be used for the acquisition of businesses, products and technologies or for other strategic