Pfizer has clinched a deal worth up to $10bn to buy weight-loss start-up Metsera, capping a dramatic takeover battle after Ozempic maker Novo Nordisk tried to gatecrash its earlier bid.

After a week-long bidding war which was prompted by Novo submitting an unsolicited offer for Metsera in late October, the weight-loss biotech said late on Friday that it had opted to pursue a deal with Pfizer because of antitrust concerns raised by the US competition watchdog over Novo’s offer.

Pfizer’s new deal to buy Metsera values the biotech at as much as $2.7bn more than an earlier agreement from September. As part of the deal, Metsera’s shareholders will receive $65.50 a share in cash upfront and a further $20.65 a share based on certain clinical trial milestones being met.