NEW YORK (CNNMoney.com) - Shares of Amazon.com tumbled Friday after a disappointing quarterly report prompted several Wall Street banks to cut their price targets.

Amazon (down $4.87 to $37.87, Research) sank 12 percent in morning trade on Nasdaq.

On Thursday, Amazon said fourth-quarter net profit fell in its crucial holiday quarter as shipping and technology costs rose while revenue was shy of Wall Street expectations.

After the online retailer's quarterly results came in below expectations, Citigroup reiterated its "sell" rating on the online retailer and recommended eBay Inc. (Research) instead, according to Reuters.

Citigroup also lowered its stock price target to $34 from $38.

Citigroup said the retailer's fourth-quarter results were below its estimates and noted that Amazon's fundamentals deteriorated as its year-over-year organic revenue growth in December decelerated to the lowest in years.

Deutsche Bank cut its price target to $38 from $44.

Bear Stearns lowered its price target to $47 from $50, saying that while Amazon's outlook was disappointing, it could be conservative.

And Piper Jaffray lowered its target on Amazon to $37 from $40 based on valuation.

-- from staff and wire reports

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