speculation meets financial evidence in pharma case

The Supreme Court of New South Wales decision in Mayne Pharma Group Limited v Cosette Pharmaceuticals, Inc. sits at the intersection of public mergers and acquisitions, valuation risk, and contractual certainty. At its core, the case examined whether a purchaser could withdraw from a signed takeover transaction by relying on a Material Adverse Change (MAC) clause when post-signing financial performance did not meet internal expectations.

The judgment provides authoritative guidance on how Australian courts interpret MAC clauses in public transactions and clarifies the distinction between commercial disappointment and legally actionable deterioration.

Background and Transaction Structure

Mayne Pharma Group Limited is an ASX-listed specialty pharmaceutical company with operations across Australia and the United States. In February 2025, Mayne entered into a Scheme Implementation Deed (SID) with Cosette Pharmaceuticals, a US-based pharmaceutical group, under which Cosette agreed to acquire all Mayne shares for A$7.40 per share in cash by way of a scheme of arrangement.

A scheme of arrangement is a court-supervised acquisition process requiring approval by shareholders and the court. Once the SID is executed, the parties are contractually bound to progress the transaction unless specific termination rights are enlivened.

The agreed consideration valued Mayne at approximately A$672 million and represented a substantial premium to Mayne’s recent trading prices. Independent expert analysis concluded the offer fell within a reasonable valuation range and was fair to shareholders in the absence of a superior proposal.

Financial Context

The valuation premium embedded in the A$7.40 offer reflected expectations about Mayne’s future earnings and operational stability. As with most public M&A transactions, those expectations were informed by forecasts rather than guarantees of future performance.

After the transaction was announced, Mayne experienced periods of weaker-than-forecast performance, including a softer third quarter relative to internal projections. While Mayne continued to operate as a going concern, the divergence between forecast expectations and actual performance became central to the dispute.

This context explains the commercial tension that followed. From the seller’s perspective, shareholders had locked in a significant premium. From the buyer’s perspective, Cosette had agreed to a fixed price that assumed certain earnings trajectories continuing through completion.

The MAC Clause

The SID contained a detailed MAC clause allowing Cosette to terminate if a “Mayne Material Adverse Change” occurred. The clause was tightly defined and required an event, change, or circumstance reasonably expected to reduce Mayne’s consolidated maintainable EBITDA by at least A$10.76 million over a 12-month period, subject to specific carve-outs.

Importantly, the clause focused on quantified financial impact, not general commercial underperformance or market sentiment.

The Dispute Emerges

In May 2025, Cosette issued a MAC notice asserting that Mayne’s financial performance relative to forecasts constituted a material adverse change. Additional notices followed, alleging breaches of representations, warranties, and disclosure obligations under the SID.

Mayne rejected those assertions, contending that no MAC had occurred within the meaning of the contract and that Cosette was attempting to exit the transaction based on forecast disappointment rather than contractual grounds.

Proceedings were commenced in the Supreme Court of New South Wales on an expedited basis, reflecting the looming transaction end date and the need for market certainty.

Legal Considerations

The case reinforces several principles relevant to public M&A:

• Deal certainty: Signed transactions are not optional arrangements subject to changing sentiment.

• Risk allocation: Forecast risk remains with the buyer unless expressly shifted.

• Drafting discipline: MAC clauses operate exactly as written, particularly where quantitative thresholds are used.

• Market stability: Courts will not permit opportunistic exits based on short-term performance variance.

  
  

Issues Before the Court

The Court was required to determine:

• Whether forecast shortfalls constituted an “event, change or circumstance” for the purposes of the MAC clause.

• Whether Cosette had demonstrated the required level of financial impact.

• Whether alternative termination rights based on representations or disclosure had been enlivened.

  
  

The Court’s Decision

The Court rejected Cosette’s termination attempt and upheld the validity of the SID.

Forecasts vs Actual Adverse Change

A central finding was that differences between forecast and actual performance are not, of themselves, a material adverse change. Forecasts represent expectations, not facts. To trigger a MAC, there must be evidence of an actual or reasonably expected deterioration of the magnitude specified in the contract.

The Court found that Cosette had not established the required EBITDA impact on an objective basis.

Objective Construction of MAC Clauses

The Court emphasised that MAC clauses in public M&A transactions are construed strictly. Where parties agree to precise numerical thresholds, courts will not dilute those standards by reference to commercial disappointment or shifting risk appetites post-signing.

Other Termination Grounds

Cosette’s alternative claims based on alleged breaches of representations, warranties, and disclosure obligations were also rejected. The Court found no established breaches capable of justifying termination under the SID.

Outcome

The Court declared that:

• Cosette’s MAC notice and purported termination were invalid

• The SID remained on foot

• Cosette was not entitled to terminate on the grounds advanced

• Cosette’s cross-claims for damages and break fees were dismissed

While subsequent regulatory developments ultimately affected the transaction’s completion, those matters sat outside the MAC analysis before the Court.

Professional Significance

For corporate lawyers, boards, and advisers, Mayne Pharma v Cosette underscores that MAC clauses are protective mechanisms of last resort, not tools for repricing or renegotiation. In an environment where valuation premiums are often justified by forward-looking assumptions, the decision affirms that the legal threshold for termination remains deliberately high.

The judgment strengthens confidence in Australia’s public M&A framework by reinforcing that contractual certainty, once achieved, will be upheld according to objective and measurable standards rather than retrospective commercial reassessment.

Authored by Campbell Dore

Publisher

The Brief

campbell@thebrieflaw.com.au