'We don't think it can get much better from here for Roku,' says Stephens in downgrade

The Roku 3 television streaming player menu is shown on a television in Los Angeles, California, U.S., on Thursday, Sept. 12, 2013.
Patrick T. Fallon | Bloomberg via Getty Images

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With Roku's TV partner pulling most of the weight, there's less upside for the streaming platform going forward, according to Stephens. 

The Wall Street firm downgraded shares of Roku to equal weight from overweight on Friday, largely due to its partnership with Smart TV company TCL. The call sent shares of Roku down nearly 3% in premarket trading.