Novo Nordisk raised its offer for obesity drug developer Metsera to as much as $10 billion, escalating a bidding war with Pfizer and pushing Metsera’s board to declare Novo’s proposal superior. Novo’s structure would pay a large dividend on signing and acquire remaining shares later, a tactic that has drawn regulatory attention. The dispute has already generated litigation from Pfizer and heightened antitrust scrutiny of consolidation in the obesity-drug market.