Five weeks ago, Hollywood was in the doldrums. A succession of hotly tipped blockbusters – The Fall Guy, Furiosa, IF – flopped. The mood was ominous. The last time early summer box-office takings had been so low was in 2000.

Today, considerably more cheerful records are being broken, thanks entirely to children’s films. Three weeks ago saw the release of Inside Out 2, Pixar’s sequel to its 2015 animation about the emotions jostling for supremacy in the head of an 11-year-old girl named Riley.

Even the most optimistic-seeming predictions were that it would make $80m (£62m) on its first weekend of release in the US. In fact, it made $155m (£121m). On its second weekend, ticket sales only dropped by 35% (by comparison, Barbie’s fell 43% over the same period in 2023). Last week, Pixar’s latest became the fastest film ever to make a billion dollars worldwide – in just 19 days.

In the US, however, it will lose its place at the top of the chart this weekend, when it is toppled by another children’s animation sequel. Despicable Me 4 opened in the US on Wednesday, taking $27m (£21m), and is on course for a five-day total of $120m (£94m) over the Independence Day holiday. (It opens in the UK next Friday.)

“Success begets success,” says Steven Gaydos, executive editor of Variety. Parents who enjoyed taking their children to Inside Out 2 are now primed to repeat the experience. “A rising tide lifts all boats.”

Yet the scale and speed of Inside Out 2’s triumph remains mysterious. “Its explosive success is a potent reminder of what happens when everyone in the world wants to see the same movie,” says Gaydos. “There is pent up demand that lands on the same square the same day. It’s beyond marketing, beyond explanation.”

Chris Meledandri, founder and CEO of Illumination, a division of Universal Pictures and the production studio behind Despicable Me, concurs. “People were missing the cinema,” he says. “So the minute the signals started to flash that Inside Out 2 was the film they’d been waiting for, you saw a kind of a spontaneous eruption.”

Even Inside Out 2’s writers were taken aback. “It’s always surprising when four million people show up to your movie,” says Dave Holstein. His father texted to apologise for not being able to see it over opening weekend. “Go to a different theater,” his son texted back. “All sold out,” came the reply. “Every screen, every time.”

When Holstein’s co-writer, Meg LeFauve, went to her local cinema on the first Saturday after the film’s release, she was struck by the sight of the popcorn queue snaking round the block. “At the end of the film,” she says, “everybody stood up and cheered. I thought: ‘Oh, OK, we might’ve touched a chord. This could be big.’”

Much was resting on Inside Out 2’s pulling power. Pixar head Pete Docter, who directed the first film and executive produced the second, last month admitted to muted hopes and minimal fingernails. Should the sequel sink at the cinema, he said, “we’re going to have to think even more radically about how we run our business”.

The problem Docter identified was a pandemic hangover. Pixar’s decision to release two key titles, Soul and Elemental, straight to streaming had likely habituated audiences to seeing such films on their own sofas.

However, Holstein thinks this trend may have helped Inside Out 2. “The number of people who have seen the first film has grown exponentially since it first came out, because so many people have now caught up with it on Disney+.”

Inside Out 2 is a family film with cross-generational appeal. It appeals to young children, teenagers (the new movie sees Riley’s headquarters co-opted by Anxiety as she turns 13), twentysomethings who loved the first film, plus parents and grandparents. “It’s many movies in one,” says Holstein. “My six-year-old thinks it’s the funniest movie he’s ever seen. My mom thinks it’s the saddest movie she’s ever seen. When my son sees it in 10 years, he’ll have a whole different movie to watch.”

While less obviously ambitious offerings such as Super Mario Bros (2023’s second-best-performing film, after Barbie), plus 2024’s Kung Fu Panda 4 ($545m/£425m) and Garfield ($240m/£187m), were respectable performers, their target demographic is narrower and takings were correspondingly capped.

Inside Out’s reach, by contrast, means it performs less like a family film and more like an event movie in the moulds of Marvel or Barbie. Nineteen per cent of its opening weekend audience were aged between 25 and 34, and 18% were between 18 and 24. It seems adults aren’t only willing and eager to take the children – they’re willing and eager to go without them.

More surprisingly, this also appears to be the case with Despicable Me 4. Exit figures from its first day of US release suggest 59% of the audience were over 18, with a further 20% aged 13-17. “What we’re finding,” says Meledandri, “is that there’s a very strong nostalgia factor, which means it’s actually playing across all ages.”

Audiences’ responses also more closely mirror those towards “a full-blown comedy”, says Meledandri, than traditional family fare. “And comedy in theatrical films is becoming more and more rare.” Even rarer is mainstream comedy that translates across international territories – something at which the film’s Spanglish-jabbering minion characters (“language-agonistic,” says Meledandri) are old pros.

“Every part of the world can really lay claim to them in a primary manner,” says Meledandri, “and have the exact same enjoyment.”

Both films also boast a significant female skew. Inside Out 2 features almost no male characters, while Gru’s focus remains on protecting the three orphan girls he has adopted.

And both are buoyed by having a nimble US improv star fronting their promotional drive: Steve Carell (who voices Gru) in the case of Despicable Me 4, and for Inside Out 2, Amy Poehler, who voices Joy.

“They both have incredible comedy chops, but also huge hearts,” says LeFauve. “Amy is inseparable from Joy. So it’s wonderful from a marketing perspective that she really seems to walk out of the screen.”

Yet the business model behind the two series diverges dramatically. Meledandri founded Illumination in 2007, when “a consistency of box-office success” for market leaders DreamWorks, Disney and Pixar meant “the pressure wasn’t really there on cost containment”.

His strategy put sustainability at the centre – with rapid returns. The Despicable Me series is now the top-grossing animated franchise of all time, with box-office takings of almost $5bn (£3.9bn). Profit margins are widened by budget consistency: the first Despicable Me cost $69m (£53.8m) in 2010, the fourth cost $70m (£54.6m). Inside Out 2 cost $200m (£156m).

“The old formula that the second instalment would do 75% of the business of the first film, and so on, has been thrown out of the window,” says Gaydos.

Meledandri’s model has set significant industry precedent. Now, “managing costs has become much more prevalent,” he says, applauding Disney for doing so within such a large and long-established organisation.

Despite this belt-tightening, says Gaydos, “right now, anyone who is in the animation field must be feeling really good. These look like good bets to people who invest in a big way with family movies.”

And the key word, he says, is “family” – not “animation”. “Remember that Barbie, which was a huge movie, an Oscars movie, a talking-point movie, was still a movie about a kids’ toy.”

The difference is that family films are now the predominant genre for everyone. The pictures stayed small. It’s the audiences that got big.