Starboard Value has taken a stake in Pfizer, people familiar with the matter said.The drug giant's stock price has dropped significantly since its COVID-19 vaccine rollout.Starboard's stake in Pfizer is reportedly worth about $1 billion.

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.

Starboard has reached out to former Pfizer CEO Ian Read and ex-finance chief Frank D'Amelio, and both have expressed interest in supporting the activist investor's turnaround efforts, reports said.