Metsera Inc. shares saw a significant drop of up to 16% in premarket trading, following news that Novo Nordisk A/S would not raise its offer further in the face of competition from Pfizer Inc.

Pfizer (PFE) announced on Monday that it will acquire weight-loss drug developer Metsera (MTSR) in a deal valued at up to $4.9 billion, aiming to strengthen its foothold in the rapidly growing obesity treatment market.