Just months ago investors were cheering the stock of Walgreen Boots Alliance Inc. (WBA) as a solid buy on its revamped deal with Rite Aid Corp. (RAD). Now, analysts have turned sour on the drugstore chain.

Health care investment bank Leerink Partners warns clients on potential downside in WBA shares as the Deerfield, Illinois-based company faces intense competition on a number of fronts, including the expected entrance of e-commerce giant Amazon.com Inc. (AMZN) into the market. (See also: Amazon Will Next Take Retail Pharmacy: Bernstein.)

Leerink Partners’ David Larsen issued a research note on Wednesday downgrading WBA to market perform. The analyst also reduced his price target to $72 from $86, 7.8% above Thursday's close at $66.78.

“The headwinds in the pharmacy retail industry are intensifying, and we do not see any relief in the medium term,” wrote Larsen. “We believe Amazon will be entering into the market within the next few years, and we believe WBA is most exposed to share loss.”

The FTC Weighs In

While the Seattle-based tech giant is expected to announce by Thanksgiving if it will enter the market, the analyst highlights a new $66 billion deal between CVS Health Corp. (CVS) and insurer Aetna Inc. (AET) as a threat to Walgreens. In September, the U.S. Federal Trade Commission finally approved the Walgreens and Rite Aid deal but did not allow all of Rite Aid’s stores to be acquired, leaving 2,600 to still compete with Walgreens and CVS.

“WBA, CVS and RAD are seeking to capture share by accepting lower reimbursement rates from plans and PBMs [pharmacy benefit managers], thereby putting downward pressure on WBA’s gross margin,” wrote the Leerink analyst, noting that CVS recently signed deals with Anthem Inc. (ANTM), United Health’s (UNH) Optum platform, Cigna Corp. (CI) and Aetna to capture Medicare preferred network patients.

“We believe that CVS is taking the right steps to capture volumes, after a difficult 2017. In 2018 and beyond we would expect these deals to cause WBA's retail prescription volume growth rate to slow, and we would expect WBA's response to be to continue to lower reimbursement rates in an effort to capture volumes,” added Larsen. (See also: Amazon Could Buy Walgreens, Rite Aid, Express Scripts.)