Investing.com -- Pfizer is preparing to sue Metsera and potentially Novo Nordisk after the Danish drugmaker outbid Pfizer for the U.S. obesity biotech firm, according to a Semafor report Thursday.

Pfizer reportedly plans to claim that Novo’s bid doesn’t qualify as "superior" to Pfizer’s agreed $7 billion deal and skirts regulatory approvals. Novo Nordisk launched a rival bid worth up to $8.5 billion, including $6 billion upfront and milestone payments, compared to Pfizer’s $7.3 billion offer including milestones.

The acquisition represents Pfizer’s delayed entry into the $150 billion weight-loss drug market after abandoning its efforts to produce a weight-loss pill. Pfizer is positioning itself and Metsera as U.S. national champions, characterizing Novo’s bid as a foreign attempt to eliminate competition.

"It is 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 stated.

Novo Nordisk, maker of blockbuster weight-loss drug Wegovy and diabetes drug Ozempic, made its move Thursday, disrupting Pfizer’s plans. Metsera’s board had previously rejected Novo’s two-step deal as too risky despite its higher price.

The Wall Street Journal also reported Thursday that Metsera was previously in exclusive talks with Bristol-Myers Squibb before the current bidding war emerged.