Company: ARWR
Filing Date: 2025-12-11
Form Type: S-3ASR
Source: 0001193125-25-314755
Chunk: 19

Company: ARROWHEAD PHARMACEUTICALS, INC.
Filing Date: 2025-12-11
Form: S-3ASR
Chunk 19
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 also disclose whether any of the selling stockholders has held any position or office with, has been employed by or otherwise has had a material relationship with us during the three years prior
to the date of the applicable prospectus supplement, or post-effective amendment.

15

PLAN OF DISTRIBUTION We may sell the securities covered by this prospectus from time to time in any manner permitted under the Securities Act. Registration of the securities covered by this prospectus does not mean, however, that those securities will necessarily be offered or sold. We may sell the securities separately or together:

| • |     | through one or more underwriters or dealers in a public offering and sale by them; |

| • |     | directly to investors; |

| • |     | to dealers; or |

| • |     | through agents. |

We may also make direct sales through subscription rights distributed to our stockholders on a pro rata basis, which may or may not be transferable. In any distribution of subscription rights to stockholders, if all of the underlying securities are not subscribed for, we may then sell the unsubscribed securities directly to third parties or may engage the services of one or more underwriters, dealers or agents, including standby underwriters, to sell the unsubscribed securities to third parties. We may sell the securities from time to time:

| • |     | in one or more transactions at a fixed price or prices, which may be changed from time to time; |

| • |     | at market prices prevailing at the time of sale; |

| • |     | at prices related to such prevailing market prices; or |

| • |     | at negotiated prices. |

Any of the prices may represent a discount from prevailing market prices. We will describe the method of distribution of the securities and the terms of the offering in the applicable prospectus supplement. Any discounts or concessions allowed or re-allowedor paid to dealers may be changed from time to time. We may also sell equity securities covered by this registration statement in an “at the market offering” as defined in Rule 415(a)(4) under the Securities Act. Such offering may be made into an existing trading market for such securities in transactions at other than a fixed price, either:

| • |     | on or through the facilities of Nasdaq or any other securities exchange or quotation or trading service on which 
 such securities may be listed, quoted or traded at the time of sale; and/or                                      |

| • |     | to or through a market maker otherwise than