Highlights

  • Mayne Pharma announced that the New South Wales Court of Appeal dismissed Cosette’s appeal on all grounds.
  • The ruling upheld the findings that no material adverse change or misleading conduct had been established.
  • The company was awarded its appeal costs, with the amount still to be determined.
  • Cosette has until 11 November 2026 to seek special leave to appeal to the High Court.
  • Mayne Pharma intends to pursue separate damages claims, whose outcome and value remain uncertain.

Mayne Pharma Group Limited (ASX:MYX) is a specialty pharmaceutical company focused on women’s health, dermatology and pharmaceutical development and manufacturing services. On 14 October 2026, the company announced a significant court decision relating to its disputed proposed transaction with Cosette. The outcome clarifies several contested contractual issues, while leaving potential further proceedings and financial consequences unresolved.

Why Did the Court Dismiss the Appeal?

According to Mayne Pharma Group Limited (ASX:MYX), the Court of Appeal of the Supreme Court of New South Wales rejected every ground advanced by Cosette. The appeal challenged findings that no Mayne Material Adverse Change had occurred and that Mayne Pharma had not engaged in misleading or deceptive conduct concerning the financial performance disputed during the transaction process. The appellate decision affirmed the lower court’s findings, as described in the company’s announcement.

The Scheme Deed and Contractual Rights

The company said the appeal court also concluded that Cosette, through its conduct at the first court hearing concerning the proposed scheme, had elected to affirm the scheme implementation deed. On the company’s account, that election meant Cosette had relinquished any alleged right to terminate the arrangement. The ruling does not establish that the acquisition has completed.

What Does the Decision Mean for Legal Costs?

Mayne Pharma Group Limited (ASX:MYX) reported that it was awarded its costs of the appeal, although the court has not yet determined the amount. The company separately noted that Cosette paid approximately A$14.4 million in May 2026 toward costs of the earlier proceeding. That payment is unaffected by the latest decision. The new costs award should not be treated as an additional confirmed cash receipt until its amount and recovery are established.

Could the Dispute Continue in the High Court?

The announcement states that Cosette has until 11 November 2026 to decide whether to apply for special leave to appeal to the High Court of Australia. An application is not itself a further hearing on the merits, and there is no certainty special leave would be granted. Mayne Pharma Group Limited (ASX:MYX) has not stated whether Cosette intends to apply. Consequently, the October appellate judgment is a major procedural development but may not be the final stage of the litigation.

Damages Claims Remain a Separate Uncertainty

Mayne Pharma Group Limited (ASX:MYX) also said it intends to continue pursuing damages claims connected with the Cosette transaction, including claims involving Cosette-related parties and controllers. Those claims are distinct from the costs awarded in the appeal. The company’s announcement did not quantify the damages sought, identify a hearing timetable or establish any probable recovery. Neither the existence of the claims nor the appeal outcome should be interpreted as a forecast of income or cash receipts.

Key Insights

Mayne Pharma Group Limited (ASX:MYX) has reported a favourable appellate decision in its dispute with Cosette, supporting the earlier findings and securing a further, unquantified costs award. The next milestones are any special-leave application and progress on separate damages proceedings. The financial outcome of these unresolved matters cannot be determined from the October announcement alone.