While both the companies have insisted that the merger would benefit customers, many critics argue that the deal could lead to a rise in drug prices.
They also claim that it will be challenging for the combined company to withstand competition from Amazon (AMZN), which has forayed into the healthcare segment by acquiring online pharmacy PillPack.
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Earlier the news of Amazon entering into the competitive healthcare space had sent insurers, drug store chains and retailers into frenzy.
CVS Health’s (CVS) acquisition of Aetna (AET) had marked a new wave of vertical mergers in the healthcare space. In March, pharmacy benefits manager Express Scripts agreed to be acquired by Cigna in a deal that currently is being reviewed by Department of Justice. In April, the DOJ had asked for additional details on the deal.
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Cigna witnessed a surge in its share price after the news broke out, whereas shares of Express Script traded in the negative territory on Wednesday.