Company: WHWK
Filing Date: 2025-04-25
Form Type: 424B5
Source: 0001193125-25-097064
Chunk: 1

Company: Whitehawk Therapeutics, Inc.
Filing Date: 2025-04-25
Form: 424B5
Chunk 1
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 market prices by any method that is deemed to be an “at the market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended (the
“Securities Act”), including without limitation sales made through the Nasdaq Capital Market or on any other trading market for our common stock, or by any other method permitted by law. TD Cowen is not required to sell any specific amount
of securities, but will act as our sales agent using commercially reasonable efforts consistent with its normal trading and sales practices, on mutually agreed terms between TD Cowen and us. There is no arrangement for funds to be received in any
escrow, trust or similar arrangement.

The compensation to TD Cowen for sales of common stock pursuant to the sales agreement will be an amount equal to 3.0% of the
gross proceeds of any shares of common stock sold under the sales agreement. In connection with the sale of the common stock on our behalf, TD Cowen will be deemed to be an “underwriter” within the meaning of the Securities Act and the
compensation of TD Cowen will be deemed to be underwriting commissions or discounts. We have also agreed to provide indemnification and contribution to TD Cowen with respect to certain liabilities, including liabilities under the Securities Act or
the Securities Exchange Act of 1934, as amended (the “Exchange Act”).

Our business and an investment in our common stock involve significant risks. These risks are described under the caption “ Risk Factors” beginning on page S-9of this prospectus supplement and in the documents incorporated by reference into this prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or
adequacy of this prospectus. Any representation to the contrary is a criminal offense.

TD Cowen

The date of this prospectus supplement is
April 25, 2025

TABLE OF CONTENTS PROSPECTUS SUPPLEMENT

|                                                   |     | Page |      |
| About This Prospectus Supplement                  |     |      | S-1  |
| Market Industry and Other Data                    |     |      | S-3  |
| Prospectus Supplement Summary                     |     |      | S-4  |
| The Offering                                      |     |      | S-7  |
| Risk Factors                                      |     |      | S-9  |
| Special Note Regarding Forward-looking Statements |     |      |