Activist investor Starboard has informed Pfizer it has taken a stake Business InsiderActivist Starboard Value has $1 billion Pfizer stake, taps former executives for help, sources say CNBCPfizer Has an Activist. It’s the Latest Target of Starboard. Barron’sStarboard reportedly targets Pfizer, markets waver amid uncertainty Yahoo FinancePfizer Stock Rises on Report Starboard Takes Roughly $1B Stake Investopedia