Hear that thud? That’s the sound of Amazon getting into the retail pharmacy business. Today the online retail giant snatched up PillPack, an online pharmacy that presorts prescription drugs and delivers them to your door. Walgreens, Rite Aid and CVS all saw their stock prices take a dive in early trading on news of the deal. Amazon’s decision to spend an estimated $1 billion on a tiny company is making other pharmacies nervous.

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