Disney’s new streaming service appears to be losing steam after bolting out of the gate last year — raising questions about its ability to catch up to Netflix.

When the Mouse House launched Disney+ and its marquee Star Wars spinoff “The Mandalorian” in November, it racked up a massive 10 million subscribers in its first 24 hours — stunning both Wall Street and Hollywood.

But now Wall Street researchers are predicting that Disney+’s early success is waning, in part because anyone who wanted the service wasted no time signing up for it — leaving little room for growth.

“Disney+ has probably already achieved its peak absolute net adds in the first quarter of its existence,” Bernstein analyst Todd Juenger said in a recent research report. “In other words, there will probably never be another year where Disney+ adds as many subscribers as it did in the first year, or frankly in its first quarter.”

Juenger said he expects Disney+ to hit around 40 million subscribers by the end of the year, or just 12 million above the 28 million it racked up at end of 2019 — even as it readies to launch in Europe in March.

By contrast, online video powerhouse Netflix has added 167 million worldwide subscribers, including over 61 million in the US, since launching in 2010.

Adding to the problem is a dearth of original programming for adults to watch after they’ve binged on “The Mandalorian,” the Disney+ action series that spawned internet sensation “Baby Yoda,” noted LightShed Partners analyst Richard Greenfield.

Indeed, the bulk of Disney’s original streaming programs currently focus on children, including a live-action remake of “Lady and the Tramp,” and “Marvel Hero Project,” a show that capitalizes on Disney’s Marvel brand by making inspirational kids into superheroes with their own commemorative comics.

Disney will need to spend more on exclusive Disney+ content to attract new consumers and retain current ones, Greenfield said. The streaming service dropped $1 billion on content in 2019, and said it expects that number to rise to $2.5 billion by 2024. Netflix, by contrast, spent $15 billion on content in 2019.

“If you haven’t signed up now, what’s the catalyst?,” Greenfield said. “The single biggest question is, can they grow that US subscriber number from here? Or, have they largely maxed out in the US in weeks from launch?”

Disney, which didn’t respond to a request for comment, has plans to release a second season of “The Mandalorian” in October, and a new Marvel adventure show called “The Falcon and the Winter Soldier” in August.