Ratings-challenged CNN hit rock bottom in a key viewership demographic last weekend — another sign of the difficulties facing incoming boss Mark Thompson.

The cable news network logged its worst weekend ratings on record in the all important 25- to 54-year-old demo, according to the latest Nielsen data released Tuesday.

CNN — which launched in 1980 and bills itself as “the most trusted name in news” — totaled just 55,000 viewers for its weekend slate of shows that include Sunday political programs “State of the Union with Jake Tapper and Dana Bash,” and “Fareed Zakaria GPS.”

The network’s Sunday primetime lineup, which featured “The Whole Story with Anderson Cooper” and “Stanley Tucci: Searching for Italy,” drew 43,000 in the demo.

The ratings are the network’s worst since 1991 — the earliest TV data is readily available.

Data prior to 1991 is largely not digitized.

CNN’s overall viewership wasn’t much better.

The network logged 345,000 total viewers, trailing Fox News’ 683,000 and MSNB’s 424,000.

Fox won the battle in the key demo as well, drawing 75,000 viewers to top MSNBC’s 47,000, which finished behind CNN.

“CNN is a ratings embarrassment,” an industry insider said. “At least with Thompson they will have a direction.”

Thompson, the former New York Times Company CEO, was tapped as CNN’s new chairman and CEO last month by parent Warner Bros. Discovery after the disastrous tenure of Chris Licht.

The divisive network boss was ousted in June following a scathing profile in The Atlantic that portrayed him as a paranoid manager who was obsessed with his ousted predecessor, Jeff Zucker.

During Licht’s 13-month reign, he was tasked with shifting the network toward more centrist coverage.

His overhaul included the ill-fated shakeup of the network’s morning show, which brought together Don Lemon, Poppy Harlow and Kaitlan Collins.

The trio never clicked Lemon was fired in April after series of gaffes that included saying GOP presidential hopeful Nikki Haley was “not in her prime.”

Collins was moved to host a weekday primetime show but has failed to lift viewership.

Thompson, who helped revitalize the Times’ finances by growing the paper’s digital subscriber base as chief executive from 2012 to 2020, will take the helm at CNN beginning Oct. 9.

Inside CNN, staffers are hoping that the incoming leader, who once managed the BBC as its director general, will lean into his hard news and digital experience, to not only amp up the ratings, but also grow the network’s revenue.