Shares of Netflix  (NFLX - Get Report) tumbled Friday after the release of a critical analyst's report that downgraded the stock, citing growing competition and management flux.

Netflix's stock price dropped .85% to close Friday at $349.60, following a downgrade to neutral from buy by Buckingham Research Group.

Netflix is vulnerable to a market pullback and faces a big increase in competition in the video streaming space as Walt Disney Co. (DIS - Get Report) and other competitors gear up their own offerings, wrote Buckingham analyst Matthew Harrigan wrote.

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While Netflix now has more than 139 million members across the globe, Disney and AT&T   (T - Get Report) , through Warner Media, are readying the rollout of their own streaming platforms in the second half the year.

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Up next is Comcast,  (CMCSA - Get Report) , which is planning to hit the market in 2020 with its own streaming service through NBC Universal.

Meanwhile, the Buckingham Research analyst note also mentioned management flux as another reason for concern, with Netflix announcing Thursday that Chief Marketing Officer Kelly Bennett would be stepping down.

Over seven years, Bennett oversaw five-fold growth in Netflix's membership base, while also launching big hits like "Orange is the New Black," and "House of Cards." Netflix's stock price fell Thursday afternoon after word of Bennett's pending departure broke.

Bennett's decision to leave Netflix comes on the heels of two other big defections at the top.

David Wells, the video streaming and content company's finance chief, left in August, while communication chief Jonathan Friedland was ousted last year following "his descriptive use of the N-word on at least two occasions at work," Netflix CEO Reed Hastings wrote.