Shares of CVS (NYSE: CVS), Walgreens (NYSE: WBA) and Rite-Aid (NYSE: RAD) lost USD 12.8 Billion in value after Amazon.com, Inc. (NASDAQ: AMZN) announced that it had signed an agreement to buy the online pharmacy, PillPack, on Thursday.

PillPack organizes and delivers presorted doses of medications. According to their website, it is licensed to ship prescriptions in 49 States. The Chief Executive Officer of PillPack said in November that it was on track to post more than USD 100 Million in revenue for 2017. Jeff Wilke, Amazon Chief Executive Officer Worldwide Consumer, said in a statement, “PillPack is meaningfully improving its customers’ lives, and we want to help them continue making it easy for people to save time, simplify their lives, and feel healthier. We’re excited to see what we can do together on behalf of customers over time.”

Healthcare investors anticipated Amazon’s entry into the pharmaceutical sector, with CNBC reporting Amazon hiring people to break into the multi-billion dollar market back in May 2017.

In October 2017, the St. Louis Post-Dispatch reported that Amazon had gained approval for wholesale pharmacy licenses for at least 12states, a report that aided in shrinking the stocks of CVS, Walgreens, and Rite-Aid over 10% in the last 12 months.

Over 4 Billion prescription orders are made in the U.S. every year. Patients, insurance companies and others spent about USD 300 Billion on prescription drugs in 2015. The Companies expect the deal to close during the second half of 2018.

Walgreens Boots Alliance recognized Amazon’s move into the pharmaceutical e-commerce space with Chief Executive Officer, Stefano Passina, describing it as “a declaration of intent from Amazon” and that “the pharmacy world is much more complex than the delivery of certain [pills or] packages.” Walgreens shares were down over 1% on Thursday pre-market when the company reported its third-quarter earnings results and announced a USD 10 Billion share buyback, before the news of the Amazon-PillPack deal.

Other drug distributors stocks McKesson, Cardinal Health, and AmerisourceBergan dropped more than 6% upon the news.