US biotech viewed as lucrative target partly because of its promising pipeline of weight-loss drugs

Novo Nordisk has launched a surprise $9bn (£6.9bn) offer for the US obesity-focused biotech firm Metsera that could gazump an existing bid from Pfizer as the pharmaceutical giants fight for dominance in the weight-loss market.

The bid comes weeks after Metsera agreed to a $7.3bn takeover from the US group Pfizer. Denmark’s Novo Nordisk, which owns the weight-loss drugs Ozempic and Wegovy, lost out in a competitive auction processin September.

Pfizer criticised the unsolicited bid, accusing Novo Nordisk of making a “reckless” offer and claiming it was “an attempt by a company with a dominant market position to suppress competition in violation of law by taking over an emerging American challenger”.

Pfizer now has just four business days to sweeten its offer for the American upstart, which listed on the Nasdaq index earlier this year.