"Yes, it's a declaration of intent from Amazon," said Walgreens CEO Stefano Pessina on the call, according to a transcript from FactSet. "[But] the pharmacy world is much more complex than the delivery of a certain [pill or] packages." Walgreens shares were down slightly more than 1 percent in Thursday's premarket session after the company reported its fiscal third-quarter earnings results and announced a $10 billion share buyback. Then the Amazon-PillPack news was released, and Walgreens shares traded sharply lower and ended the day down 9.9 percent.