A spate of streaming services are on their way from major tech and entertainment companies, promising viewers a trove of binge-worthy new shows and movies.

There’s something for advertisers, too: your personal data.

Recent deals involving the media conglomerate AT&T, the streaming device seller Roku, the advertising giant Publicis and other companies have expanded the surveillance infrastructure that operates in the background of streaming services. While viewers focus on the action onscreen, tracking technology quietly sops up information about their habits and uses it to target them with more relevant, traceable ads.

It is a “digital daisy chain of data-gathering on viewers,” according to Jeff Chester, the executive director of the Center for Digital Democracy. Many streaming customers are unaware that the sitcom titles they prefer, the ads they do not skip, their email addresses and the serial numbers identifying the devices they use are being harvested and distributed. Others willingly opt in to, say, have a record of their recent cooking show binge, watched through Amazon Fire TV, transmitted to an advertiser that can then deliver a recipe book ad to their laptop or tablet.

But recent research suggests that even when viewers try to shield their information, it is sometimes tracked without their permission and shared with corporate giants like Facebook, Google and Netflix.