Denmark's Novo Nordisk launched a rival bid for U. obesity biotech firm Metsera on Thursday, hijacking an offer from Pfizer as drugmakers jostle for advantage in the fast-growing and competitive weight-loss drug market.

From a more company-specific point of view, Pfizer has also agreed to buy Metsera. This will help the company deal with upcoming patent cliffs, in which older drugs lose their patent protections. The acquisition was necessitated by the fact that Pfizer's own drug pipeline was looking a little weak.