Amazon.com Inc. (AMZN - Get Report) is making its way into the pharmaceutical retail business.

The retail giant announced Thursday, June 28, that it had entered into a "definitive merger agreement" with PillPack, an online pharmacy that specializes in delivery. 

U.S.-based PillPack is a pharmacy company that focuses on customers who take multiple-daily prescriptions. "PillPack delivers medications in pre-sorted dose packaging, coordinates refills and renewals, and makes sure shipments are sent on time," the press release states. 

Amazon's Worldwide Consumer CEO Jeff Wilke stated in a Thursday release, "PillPack's visionary team has a combination of deep pharmacy experience and a focus on technology."

"Amazon's acquisition of PillPack is a warning shot in what is about to become a major battle within the pharmacy space. Not only has Amazon finally made a solid move into pharmacy, it has done so via an innovative supplier which helps patients manage and organize their prescription drugs," wrote Neil Saunders, managing director of GlobalData Retail in an email.

The deal has shaken Wall Street's confidence in other pharmaceutical retailers.

In early trading after the deal was announced. Walgreens Boots Alliance Inc. (WBA - Get Report) was down over 10%, CVS Health Corp. (CVS - Get Report) was down nearly 9% and Rite Aid (RAD - Get Report) was down 11%.

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