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AstraZeneca exercises option to buy SixPeaks Bio

10 November 2025

AstraZeneca has finalised the acquisition of Swiss biotech SixPeaks Bio in a deal valued at up to USD 300 million, reinforcing its push into next-generation obesity treatments that emphasize muscle preservation. The agreement includes a USD 170 million upfront payment, an additional USD 30 million in two years, and up to USD 100 million tied to regulatory milestones. The acquisition, completed in late October, marks a key step in AstraZeneca’s broader effort to redefine obesity care as a metabolic and medical challenge rather than a cosmetic issue.

SixPeaks Bio, launched by Versant Ventures in 2024 through its Ridgeline Discovery Engine in Basel, is developing bispecific antibodies that block activin type IIA and IIB receptors. This mechanism is designed to help patients shed fat while maintaining muscle mass.

Walder Wyss advised SixPeaks Bio AG and its shareholders (incl. Versant Ventures) on all Swiss law aspects of the transaction. The team was led by Robert von Rosen (Partner, Corporate/M&A) and Alexander Gutmans (Partner, Corporate/M&A and Venture Capital) and further included Karina Tschon (Managing Associate, Corporate/M&A and Venture Capital), Michelle Bruni (Managing Associate, Tax), Christoph Burckhardt (Senior Associate, Corporate/M&A), Bojan Momic (Senior Associate, Corporate/M&A), Oerjan Wickart (Associate, Corporate/M&A) and Lorenzo Petrone (Associate, Corporate/M&A).

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