Company: RDPTF
Filing Date: 2025-12-10
Form Type: 20-F/A
Source: 0001213900-25-119835
Chunk: 0

Company: Radiopharm Theranostics Ltd
Filing Date: 2025-12-10
Form: 20-F/A
Chunk 0
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As filed with the Securities and Exchange Commission on December 10, 2025 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 20-F/A (Amendment No. 1) (Mark One)

| ☐ | REGISTRATION                                                                      
 STATEMENT PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 |

OR

| ☒ | ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 |

For the fiscal year ended June 30, 2025 OR

| ☐ | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 |

OR

| ☐ | SHELL COMPANY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 |

Date of event requiring this shell company report For the transition period fromto Commission file number 001-41621 RADIOPHARM THERANOSTICS LIMITED (Exact name of Registrant as specified in its charter) Not Applicable (Translation of Registrant’s name into English) Australia (Jurisdiction of incorporation or organization) Level 3, 62 Lygon Street Carlton VIC 3053
Australia (Address of principal executive offices) Riccardo Canevari, Chief Executive Officer Level 3, 62 Lygon Street
Carlton VIC 3053
Australia Phone: +61 3 9824 5254E-mail: rc@radiopharmtheranostics.com (Name, Telephone, E-mail and/or Facsimile number and Address of Company Contact Person) Securities registered or to be registered, pursuant to Section 12(b) of the Act:

| Title of each class                                           |     | Trading Symbol(s) |     | Name of each exchange on which registered |
| Ordinary Shares, as represented by American Depositary Shares |     | RADX              |     | The Nasdaq Stock Market LLC               |

Securities registered or to be registered pursuant to Section 12(g) of the Act: None Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act: None The number of ordinary shares outstanding as of June 30, 2025 was 2,364,949,502ordinary shares. Indicate by check mark if the registrant is