Starboard’s stake comes amid a time of struggle at the drugmaker, which has begun to cut costs aggressively as demand for its Covid-19 medicines recedes.

Activist investor Starboard Value has taken a stake of about $1 billion in Pfizer and wants the U.S. drug giant to make changes to turn its performance around, sources familiar with the matter said on Sunday.

Pfizer's (PFE, Financial) stock experienced a boost on Monday, surging by 3 %, following the news that activist investor Starboard Value has acquired a substantial stake in the pharmaceutical giant. The investment,