A great switch-off is under way on US primetime television with a majority of cable channels losing viewers in 2015, a trend that is reshaping the media landscape and rattling investors.

美国观众正大举放弃在黄金时段观看电视节目，今年大多数有线电视频道的收视率都出现下滑，这一趋势正在重塑媒体格局，并让投资者不安。

Audience data compiled by Nielsen, the research firm, show that 26 of the top 35 cable channels attracted lower average primetime audiences in 2015 compared with 2014. ESPN, Bravo, Comedy Central and MTV were among those hit.

研究机构尼尔森(Nielsen)编制的收视率数据显示，2015年，在最受欢迎的35个有线电视频道中，有26个频道的黄金时段平均观众数量低于2014年，其中包括ESPN、Bravo、Comedy Central和MTV。

“This is a multiyear issue and is leading to lower industry advertising growth,” said Michael Nathanson, a media analyst with MoffettNathanson. “A business that had been growing in advertising is now struggling.”

“这种情况已持续多年，正导致行业广告增速下滑，”墨菲特纳萨森公司(MoffettNathanson)媒体分析师迈克尔纳萨森(Michael Nathanson)表示，“曾经在广告收入方面增长的行业现在步履维艰。”

Lower audience ratings and fears about “cord-cutting” — the cancellation of cable and satellite television subscriptions — hit US media shares in 2015 with the S&P 500 Media Index falling 5.5 per cent, far more than the broader market, which was flat for the year.

收视率下滑以及对“掐线”（cord-cutting，取消有线电视和卫星电视订阅）的担忧在2015年打击了美国的传媒类股，标准普尔500指数(S&P 500)的传媒指数(Media Index)下跌5.5%，跌幅远超大盘，今年标普500与去年持平。

Walt Disney, which recently released Star Wars: The Force Awakens , and AMC Networks, home of The Walking Dead series, are the only media companies to end the year with their shares up on 2014. Disney sparked a sell-off in media stocks this summer when it warned that subscriber growth at its ESPN network had slowed. The channel lost an estimated 3m subscribers in the year to August, said Nielsen.

2015年进入尾声之际，股价较2014年上涨的传媒公司只有沃尔特迪斯尼公司(Walt Disney)和AMC Networks。迪斯尼最近发布了《星球大战：原力觉醒》(Star Wars: The Force Awakens)，而AMC Networks的频道播放电视剧《行尸走肉》(The Walking Dead)。迪士尼今年夏季警告称，旗下ESPN频道的订户增长放缓，这引发了传媒股的抛售潮。尼尔森表示，ESPN在截止今年8月的一年时间里失去了约300万订户。

Lower average audience ratings for cable networks are indicative of a big shift in viewing habits. Audiences are increasingly using on-demand streaming services, such as Netflix, Amazon and Hulu, rather than tuning in to watch live television. “The world is moving to on-demand viewing,” Mr Nathanson said.

有线网络的平均收视率下降表明，观看习惯发生了重大转变。观众日益使用Netflix、亚马逊(Amazon)和Hulu等点播流媒体服务，而不是打开电视看直播。纳萨森表示：“世界正在转向点播观看。”