Amazon is acquiring online pharmacy PillPack in a deal that is already shaking up the drugstore industry. 
 
 The move is the strongest indication yet of Amazon's intent to push further into the health-care industry. It threatens to remove one of the few distinguishing factors pharmacy chains have relied on to fend off Amazon, the sale of prescription drugs. Retailers like Walgreens Boots Alliance, CVS Health and Rite Aid have seen their so-called front of store sales threatened as shoppers increasingly buy household staples online or from convenience stores. 
 
 Shares of all three tanked Thursday on the news, along with drug distributors Cardinal Health, AmerisourceBergen and McKesson. Rite Aid, Walgreens and CVS Health lost about $12.8 billion in market value on Thursday alone. 
 
 PillPack, which organizes and delivers packages of medications for consumers, is licensed to ship prescriptions in 49 states, according to its website. 
 
 "Yes, it's a declaration of intent from Amazon," Walgreens Boots Alliance CEO Stefano Pessina acknowledged to analysts in a planned call to discuss its quarterly earnings, according to an initial transcript from FactSet. "[But] the pharmacy world is much more complex than the delivery of a certain [pills or] packages." 
 
 Terms of the deal with Amazon were not disclosed, though people familiar with the matter told CNBC that Amazon paid roughly $1 billion. The companies expect it to close during the second half of the year. 
 
 The start-up has raised $118 million in funding from investors including CRV and Menlo Ventures, and it reached more than $100 million in revenue in 2017, the company has said. In 2016 it was reported to be valued at $330 million. 
 
 The company previously had sale talks with Walmart, which had considered buying the start-up for less than $1 billion, CNBC has reported. 

 Amazon is buying online pharmacy PillPack — a move that could disrupt the drug store business. 
 
 PillPack has pharmacy licenses in all 50 states. The company delivers medications to customers in pre-sorted doses designed to make it easier for people to take multiple medications a day. 
 
 Amazon (AMZN) was widely expected to move into the pharmacy business. 
 
 And Amazon CEO Jeff Bezos, the world's richest man, is creating a health care company along with JPMorgan Chase (JPM) and Warren Buffett's Berkshire Hathaway (BRKA). 
 
 The PillPack deal is already scaring investors in the top two drug store chains. 
 
 CVS (CVS) fell 9% in early trading. Walgreens Boots Alliance (WBA), the newest Dow component, plunged more than 10%. Walgreens was already trading lower after reporting a drop in same-store sales at its US pharmacies. 
 
 Related: Amazon is already trying to disrupt health care 
 
 Rite Aid (RAD) shares also fell, as did the stocks of big drug distributors Cardinal Health (CAH) and AmerisourceBergen (ABC). 
 
 These and other health care stocks rose a few months ago after reports that Amazon may not have been interested in selling prescription drugs. So much for that. 
 
 It's not clear yet just what Amazon plans for PillPack. Will it eventually merge it into a broader health care platform on Amazon or keep it independent as it has done with other subsidiaries like shoe retailer Zappos and video site Twitch? 
 
 The fact that PillPack is already licensed to sell prescriptions may persuade Amazon to keep it independent. 
 
 But all the companies said on Thursday was the deal was subject to some regulatory approvals and that the companies hope to close the transaction during the second half of this year. 
 
 Related: PillPack vs. Express Scripts -- People suffer when business turns ugly 
 
 Walgreens doesn't seem too worried. 
 
 During the company's earnings call Thursday morning, Walgreens CEO Stefano Pessina said in response to a question about the PillPack deal that the pharmacy business is "much more complex than just delivering certain pills or certain packages." 
 
 Pessina added that physical pharmacies "will continue to be very, very important in the future." 
 
 The PillPack acquisition comes just a week after CVS announced it will start delivering prescriptions to people's homes — a response to growing competition from PillPack and Capsule, another online pharmacy startup. 
 
 Related: Amazon wants you to start a business to deliver its packages 
 
 The health care industry is also in the midst of merger mania. CVS is buying insurer Aetna for while Cigna (CI), another insurer, is scooping up pharmacy benefits manager Express Scripts (ESRX). Both deals are valued at nearly $70 billion. 
 
 Those deals were announced after two mega insurer mergers were blocked by federal judges early last year on antitrust grounds. Aetna had hoped to combine with rival Humana (HUM) while Cigna was planning to merge with Anthem (ANTM).
– There's a reason shares of CVS, Walgreens, and Rite Aid were tumbling Thursday, and it can be summed up in one word: Amazon. The retailing behemoth made its first significant move into the pharmacy business by buying PillPack, an online company that ships medications to customers' homes, reports the Wall Street Journal. It's not clear yet what Amazon plans to do with the new business, including whether it will allow the firm to remain independent (as with shoe retailer Zappos) or turn it into the foundation of a bigger health-care push, reports CNNMoney. The big pharmacy chains have been bracing for Amazon's arrival, and this deal could "shake up the drugstore industry," per CNBC. The CEO of Walgreens sought to reassure investors. "The pharmacy world is much more complex than just delivering certain pills or packages," says Stefano Pessina. "I strongly believe that the role of the physical pharmacy will continue to be very, very important in the future." The move comes after CVS announced a deal with the US Postal Service to deliver drugs to people's homes for $4.99, notes the Journal. And CVS' purchase of Aetna last year was seen as a pre-emptive strike against Amazon.