Clypd, which counts TV networks Discovery and CBS as partners, uses data to enable advertisers to target viewers more precisely by their interests. TV commercials are traditionally purchased with only the capability to target people by age and gender.

The purchase amount could not be learned. A Xandr spokesman declined to comment. Clypd did not immediately respond to a request for comment.

The deal will also add linear TV ad inventory, or ad space, from clypd's clients to Xandr Community, a product that pools advertising space from AT&T-owned properties that include WarnerMedia and DirecTV, but also third parties like cable networks A+E and AMC, the source said.

The addition helps resolve a concern from some advertising buyers that Community did not offer access to enough valuable linear TV, which still reaches a larger audience than streaming services.

The deal comes as AT&T is fending off activist investor Elliott Management, which has questioned its $85 billion (66.1 billion pounds) purchase of Time Warner. It has also called for AT&T to consider selling satellite TV provider DirecTV, which has been losing subscribers.

AT&T has resisted suggestions such as getting rid of DirecTV because that would undercut its master plan to create a powerful advanced advertising machine by stitching together wireless, satellite TV and content operations.

The plan would allow advertisers to reach the right viewers and more effectively measure their ads.

Clypd is the second deal under Xandr Chief Executive Brian Lesser, who previously led ad agency GroupM in North America, to build Xandr's ad tech capabilities. It bought AppNexus, a digital advertising tech platform, last year for a reported $1.6 billion.

(Reporting by Sheila Dang; Editing by Chris Reese and Cynthia Osterman)

By Sheila Dang