The Pfizer facility in Pleasant Prairie, Wisconsin.Kamil Krzaczynski/AFP via Getty ImagesStarboard Value has taken a stake in Pfizer, people familiar with the matter said.The drug giant's stock has dropped significantly since its 2021 COVID-19 vaccine rollout.Starboard has recently taken positions in Starbucks and Match.Starboard Value has its next target: pharma giant Pfizer.The activist investor has informed Pfizer that it has taken a significant stake in the drugmaker, people familiar with the matter told Business Insider.Pfizer stock has fallen sharply since it reached record highs in 2021 during the rollout of its COVID-19 vaccine.The Wall Street Journal earlier reported the Starboard stake.Under CEO Albert Bourla, Pfizer's annual revenue soared to $100 billion during the pandemic thanks to the release of the first COVID-19 vaccine in the US and later the antiviral treatment Paxlovid.