After 13 years on the air, the syndicated newsmagazine “The Insider” will end its run in early September.

The CBS-distributed newsmagazine has long aired in access time periods as a companion to “Entertainment Tonight.” Debbie Matenopoulos and Louis Aguirre are the current hosts.

There’s no immediate word from CBS-owned stations on what will replace the series in the lucrative 7 p.m. time slot come the fall. The opening of time slots on CBS O&Os and other affiliate stations around the country will undoubtedly be a boon for other shows in the same genre, although the timing of the decision to end “Insider” could make it harder for stations to line up replacement shows by the fall.

Twentieth Television’s new entertainment and gossip entry “Page Six TV” could stand to benefit as “Insider” incumbent stations shuffle their lineups to fill the void. CBS’ own “Inside Edition,” the veteran syndicated newsmagazine that is less entertainment-focused than “Insider” or “ET,” could also be in line for upgrades.

CBS Television Distribution execs informed “Insider” staff members of the decision to end the show on Tuesday morning.

“The Insider” has averaged about 1.6 million viewers this season and a 0.6 rating in the key women 25-54 demo. Those numbers took a toll on the show’s advertising revenue, and falling affiliate fees in a tough landscape for TV stations overall meant that “Insider” was not a viable business for CBS, even for a show that was able to share production resources with the more established “Entertainment Tonight.”

“Insider” also had a hard time differentiating its coverage of entertainment news and celebrities from “ET” at a time when the target young female audience for entertainment newsmagazine series are inundated with the latest buzz via online and social media feeds.

“Insider” debuted in September 2004 with Lara Spencer, now of “Good Morning America,” as its anchor.