Buy Amazon as Prime subscribers surge past 50 million, Cowen says

An employee stacks boxes filled with merchandise for shipment at the distribution center in Phoenix, Arizona.
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Cowen reiterated its outperform rating on Amazon shares due to the growing size of the Prime membership service and the large untapped opportunities in the clothing and grocery markets. The firm called the e-commerce giant one of the "best ideas for 2017."

"We expect Amazon to capture further share gains in large 'non-core' retail verticals (Apparel, Consumables, etc) in the US and Int'ly in '17," analyst John Blackledge wrote in a note to clients Thursday.

Amazon Prime "is underappreciated. ... We expect AMZN's Prime sub count to continue to rise as AMZN converts customers to Prime."