“Joker: Folie à Deux” is the No. 1 movie at the box office, but it might not be destined for a happy ending.

In a turn of events that only Arthur Fleck would find funny, the follow-up to Todd Phillips’ 2019 origin story about the Batman villain opened in theaters nationwide this weekend to a muted $40 million, according to studio estimates Sunday, less than half that of its predecessor. The collapse was swift and has many in the industry wondering: How did the highly anticipated sequel to an Oscar-winning, billion-dollar film with the same creative team go wrong?

Just three weeks ago, tracking services pegged the movie for a $70 million debut, which would still have been down a fair amount from “Joker’s” record-breaking $96.2 million launch in Oct. 2019. Reviews were mixed out of the Venice Film Festival, where it premiered in competition like the first movie and even got a 12-minute standing ovation.

But the homecoming glow was short-lived, and the fragile foundation would crumble in the coming weeks with its Rotten Tomatoes score dropping from 63% at Venice to 33% by its first weekend in theaters. Perhaps even more surprising were the audience reviews: Ticket buyers polled on opening night gave the film a deadly D CinemaScore. Exit polls from PostTrak weren’t any better. It got a meager half star out of five possible.

“That’s a double whammy that’s very difficult to recover from,” said Paul Dergarabedian, the senior media analyst for Comscore. “The biggest issue of all is the reported budget. A $40 or $50 million opening for a less expensive movie would be a solid debut.”

“Joker: Folie à Deux” cost at least twice as much as the first film to produce, though reported figures vary at exactly how pricey it was to make. Phillips told Variety that it was less than the reported $200 million; others have it pegged at $190 million. Warner Bros. released the film in 4,102 locations in North America. About 12.5% of its domestic total came from 415 IMAX screens.

Internationally, it's earned $81.1 million from 25,788 screens, bringing its total global earnings estimate to $121.1 million. In the next two weeks, “Joker 2” will also open in Japan and China.

Second place went to Universal and DreamWorks Animation's “The Wild Robot,” which added $18.7 million in its second weekend, bringing its domestic total to nearly $64 million. Globally, it's made over $100 million. Warner Bros.' “Beetlejuice Beetlejuice” took third place in weekend five, Paramount's “Transformers One” landed in fourth and Universal and Blumhouse's “Speak No Evil” rounded out the top five.

The other big new release of the weekend, Lionsgate's “White Bird,” flopped with just $1.5 million from just over 1,000 locations, despite an A+ CinemaScore.

Overall, the weekend is up from the same frame last year, but “Joker's” start is an unwelcome twist for theater owners hoping to narrow the box office deficit.

Phillips and star Joaquin Phoenix have said they aspired to make something as “audacious” as the first film. The sequel added Lady Gaga into the fold, as a Joker superfan, and delved further into the mind of Arthur Fleck, imprisoned at Arkham and awaiting trial for the murders he committed in the first. It’s also a musical, with elaborately imagined song and dance numbers to old standards. Gaga even released a companion album called “'Harlequin,” alongside the film.

In his review for The Associated Press, Jake Coyle wrote that “Phillips has followed his very antihero take on the Joker with a very anti-sequel. It combines prison drama, courthouse thriller and musical, and yet turns out remarkably inert given how combustible the original was.”

The sequel has already been the subject of many think pieces, some who posit that the sequel was deliberately alienating fans of the first movie. In cruder terms, it’s been called a “middle finger.” But fans often ignore the advice of critics, especially when it comes to opening their wallets to see revered comic book characters on the big screen.

“They took a swing for the fences,” Dergarabedian said. “But except for a couple of outliers, audiences in 2024 seem to want to know what they’re getting when they’re going to the theater. They want the tried and true, the familiar.”

It has some high-profile defenders too: Francis Ford Coppola, who last week got his own D+ CinemaScore for his pricey, ambitious and divisive film “Megalopolis,” entered the Joker chat with an Instagram post.

“@ToddPhillips films always amaze me and I enjoy them thoroughly,” Coppola wrote. “Ever since the wonderful ‘The Hangover’ he’s always one step ahead of the audience never doing what they expect.”

“Megalopolis,” meanwhile, dropped a terminal 74% in its second weekend with just over $1 million, bringing its total just shy of $6.5 million against a $120 million budget.

Deadline editor Anthony D’Alessandro thinks the problem started with the idea to make the Joker sequel a musical. “No fan of the original movie wanted to see a musical sequel,” he wrote on Saturday.

The first film was also divisive and the subject of much discourse, then about whether it might send the wrong message to the wrong type of person. And yet people still flocked to see what the fuss was about. “Joker” went on to pick up 11 Oscar nominations, including best picture and best director, and three wins. It also made over $1 billion and was the highest-grossing R-rated film of all time, until this summer when Marvel's “Deadpool & Wolverine” took the crown.

Estimated ticket sales for Friday through Sunday at U.S. and Canadian theaters, according to Comscore. Final domestic figures will be released Monday.

1. “Joker: Folie à Deux,” $40 million

2. “The Wild Robot,” $18.7 million

3. “Beetlejuice Beetlejuice,” $10.3 million

4. “Transformers One,” $5.4 million

5. “Speak No Evil,” $2.8 million

6. “Sam and Colby: The Legends of Paranormal,” $1.8 million

7. “White Bird,” $1.5 million

8. “Deadpool & Wolverine,” $1.5 million

9. “The Substance,” $1.3 million

10. “Megalopolis,” $1.1 million.