Shares of Roku Inc. are up 2.1% in premarket trading after Needham analyst Laura Martin questioned whether the company would be impacted much from Amazon.com Inc.'s plans to set Fire-equipped smart TVs at Best Buy Co. Inc. News of Amazon's collaboration with Best Buy sent Roku shares tumbling in Wednesday's session. Because Amazon's partnership with Best Buy is exclusive, "this eliminates Amazon as a competitive threat in Walmart Costco Target etc, and Best Buy can still sell all other Roku TVs," wrote Needham's Martin. She also questioned the popularity of the TV brands Amazon is partnering with: "The Insignia brand has not held a top 13 TV market share in the past 10 years and the Toshiba brand fell from about 7.2% market share in 2011 to nearly zero in 2017." Martin rates Roku a buy with a $50 price target on the stock. Roku shares are down 39% so far this year, while the S&P 500 is up 1.3%.