SCHEDULE: Lantheus Entities Disclose 17.3% Stake in Radiopharm Theranostics

Lantheus Omega, LLC, along with its parent entities, has reported beneficial ownership of 17.3% of Radiopharm Theranostics Limited's ordinary shares, including significant option holdings.

Summary

• Lantheus Omega, LLC, and its affiliates Lantheus Medical Imaging, Inc. and Lantheus Holdings, Inc., have jointly filed a Schedule 13G, reporting beneficial ownership of 792,958,513 ordinary shares of Radiopharm Theranostics Limited.
• This holding represents 17.3% of the company's outstanding ordinary shares.
• The beneficial ownership includes shares acquired on August 23, 2024, January 20, 2025, and December 9, 2025, as well as options to purchase an additional 255,000,000 ordinary shares.
• These options have an exercise price of AUD$0.039 and expire on October 31, 2027.
• The filing indicates that the reporting persons do not hold these securities with the purpose or effect of changing or influencing control of the issuer.

Sentiment

Score: 7

Explanation: StockSavvy.ai views this filing as moderately positive, indicating a significant but not controlling stake in Radiopharm Theranostics Limited by Lantheus entities, with clear disclosures on shareholdings and options.

Positives

• Significant beneficial ownership of 17.3% established by Lantheus entities in Radiopharm Theranostics Limited.
• Clear disclosure of shareholdings and exercisable options provides transparency to the market.
• The reporting persons explicitly state they are not seeking to change or influence control, suggesting a passive investment approach.
• The options provide potential for increased stake at a defined exercise price.

Negatives

• The filing does not detail the financial performance or strategic direction of Radiopharm Theranostics Limited, focusing solely on ownership.
• The large number of shares and options held could be perceived as a potential future overhang on the stock price if fully exercised and sold.

Risks

• The value of the reported shares and options is subject to the market performance and future success of Radiopharm Theranostics Limited.
• The options carry an expiration date, creating a time-bound opportunity for exercise.
• Potential for future share price volatility if the reporting persons decide to exercise options and sell shares.

Future Outlook

The filing does not contain forward-looking statements or guidance from Radiopharm Theranostics Limited. The future outlook for the reporting persons is tied to the performance of their investment and the potential exercise of their options.

Management Comments

• The Reporting Persons have entered into a Joint Filing Agreement, dated September 4, 2026, a copy of which is attached as Exhibit 99.1 to this Statement, pursuant to which the Reporting Persons have agreed to file this Statement jointly in accordance with the provisions of Rule 13d-1(k)(1) under the Act.
• The Reporting Persons previously filed a Schedule 13D (the "Schedule 13D") with the SEC on September 4, 2026 related to the Ordinary Shares held by Lantheus Omega, LLC.
• The Reporting Persons no longer beneficially own more than 20% of the outstanding Ordinary Shares.
• As of the date of filing of this Schedule 13G, the Reporting Persons do not hold the securities with the purpose or effect of changing or influencing control of the Issuer.

Industry Context

StockSavvy.ai notes that this Schedule 13G filing by Lantheus entities indicates a significant passive investment in Radiopharm Theranostics Limited, a company likely operating in the radiopharmaceutical or theranostics sector. Such filings often precede or follow significant corporate events or strategic shifts within the target company.

Stakeholder Impact

• Shareholders of Radiopharm Theranostics Limited: The significant stake held by Lantheus entities may influence market perception and potential future corporate actions.
• Lantheus Holdings, Inc. and its subsidiaries: This investment represents a notable holding within their portfolio, with potential for future returns or strategic involvement.

Next Steps

• Lantheus entities will continue to monitor their investment in Radiopharm Theranostics Limited.
• The options held by Lantheus Omega, LLC may be exercised before their expiration on October 31, 2027.

Key Dates

Recommendation

The filing indicates a significant passive investment by Lantheus entities, but lacks operational or financial performance data for Radiopharm Theranostics Limited. The 17.3% stake, including options, suggests a substantial interest but not necessarily a catalyst for immediate price appreciation or depreciation, warranting a 'hold' stance pending further information on the company's performance.

Keywords

Radiopharm Theranostics, Lantheus, Schedule 13G, Beneficial Ownership, Ordinary Shares, Options, Shareholder