CVS shares fell Wednesday, a day after CNBC reported that Amazon is hiring people to push into the pharmacy business.
CVS briefly traded more than 3 percent lower Wednesday. Shares of drugstore chain Walgreens Boots Alliance fell more than 3 percent. Pharmacy benefit manager Express Scripts shares traded slightly lower.
Walgreens and Express Scripts had no comment. CVS did not immediately respond to a CNBC request for comment. Amazon declined to comment.
Amazon shares declined more 1 percent Wednesday. The stock closed at a record high Tuesday.
CNBC reported late Tuesday that Amazon is getting serious about entering the multibillion-dollar pharmacy market. One source said the e-commerce giant is hiring a general manager to lead the business development, and another source said Amazon is starting to recruit more broadly from the pharmacy industry.
Wall Street's initial reaction to the news was mixed.
Josh Brown, CEO of Ritholtz Wealth Management, raised questions in a tweet about the viability of CVS' stock if Amazon enters pharmacy.
On the other hand, Ross Muken, senior managing director and head of Evercore ISI's Healthcare Services & Technology Research Team, pointed out that "Amazon often runs pilots in different markets" and any successful strategy often takes years to unfold.
"We are somewhat skeptical that the company is definitively moving in to pharmacy given the highly regulated nature of pharmacy distribution and their seeming lack of desire to work with current" pharmacy benefit managers, Muken said in a note Wednesday. In March, Evercore played down the likelihood that Amazon could compete in pharmacy.
— CNBC's Meg Tirrell and Christina Farr contributed to this report.