Sell CBS on weaker advertising trends: UBS

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Investors should sell shares of CBS on valuation after a more than 20 percent surge this year as of Thursday, according to UBS, which downgraded the media giant to sell from neutral. The second half of 2016 and beyond holds a bleak outlook for advertising growth, the firm said.

"CBS shares have run up this year due to the strength in U.S. national TV advertising and optimism regarding management's long-term forecasts for retransmission consent revenue and CBS All Access and Showtime OTT subscribers," UBS' Doug Mitchelson wrote in a Friday note to clients. "We do not believe the macro backdrop supports continued TV advertising strength and expect decelerating national TV advertising in 2H16 ex-Olympics."