Three of the streaming-service’s top shows are foreign produced, led by Squid Game, currently its most popular series worldwide and on track to become the company’s most watched show ever, Netflix co-CEO Ted Sarandos said earlier this week at the Code tech conference.

Squid Game’s rapid rise—it ranked No. 1 in the U.S. just four days after its September 17 premiere—has been faster than any other non-English series, Netflix told Fortune. The show is now expected to be seen by more than 82 million subscribers worldwide in its first 28 days. When compared to traditional television, that’s more than the number of 18-to-49-year olds estimated by Nielsen to have watched the 40 highest-rated broadcast and cable shows of the past year combined.

If you haven’t heard of it by now, Squid Game is a survival thriller set in modern-day Seoul, where destitute people are lured into playing simple children’s games to win money — or die trying. It’s a tightly crafted, although profoundly disturbing, nine-part series steeped in dystopian horror that’s a cross between Hunger Games, British sci-fi series Black Mirror, and the Oscar-winning South Korean drama, Parasite.

But Squid Game is not only topping the charts at Netflix, it’s also the most talked-about show across rival streaming platforms Amazon Prime Video, Disney+, HBO Max, Hulu and Apple TV+, Parrot Analytics CEO Wared Seger said. The media insights firm measures TV audience demand across social media chatter and Google search trends, among other sources.

Squid Game has become such a hit that fans are now watching TikTok videos to learn how to make Squid Game related-candy (a plot point in the show), and selling merchandise that’s inspired by the series, like Halloween costumes, throw pillows and business cards. In South Korea, Squid Game is so highly-watched that a local Internet provider is suing Netflix to pay for the huge increase in bandwidth use caused by people streaming the show.

Anatomy of a hit

Behind Squid Game’s sudden success is Bela Bajaria, Netflix’s Global TV chief who took the helm a year ago and oversees production of local language originals in 40 countries.

With 65% of Netflix’s 209 million subscribers outside of the U.S. and Canada, she has been doubling down on investment in overseas markets. In Korea alone, Netflix spent $700 million from 2015 through 2020 to produce 80 films and series, and plans to spend another $500 million this year. Business consulting firm Deloitte estimates that Netflix has contributed $5.6 trillion won (equivalent to $4.7 billion in U.S. dollars) to the Korean economy.

“Our goal is to work with local creators to tell their story as authentically as possible,” Bajaria told Fortune. “What we have found when we do this is that there have been a half-dozen shows that have traveled around the world like Lupin from France and La Casa de Papel (Money Heist) from Spain.”

But she said Netflix does not rely on algorithms to identify the types of shows to make.

“We greenlight shows based on gut and human judgment. It’s the idea, the tone, and alchemy of so many things coming together,” said Bajaria. “There’s just no substitute for that.”

She explained that there was no data that could have told her team that a period drama about a woman playing chess—The Queen’s Gambit, released last year— was something subscribers wanted. Yet it became a hit that would go on to win 11 Emmys and become Netflix’s eighth-most popular series, watched by 62 million subscribers globally.

“For Squid Game, we knew it was going to be big in Korea because it had a well-regarded director with a bold vision,” she said, referring to Hwang Dong-hyuk, known for dark social justice films. “K-Dramas also travel well across Asia.”

But the show spiking to No. 1 globally as fast as it did took her by surprise. In trying to identify how it caught fire, she pointed to trends that may have played a part.

“In the U.S., the viewing of K-Dramas are up 200% and the viewing of non-English series are up 71% since 2019,” said Bajaria, explaining that once subscribers discover a non-English show and enjoy it, they are more likely to watch the next one. Ninety-seven percent of Netflix’s U.S. subscribers have watched at least one non-English title in the last year.

Analysts weigh in

Of course, Netflix can often make a hit just by saying so. 

A promotional image for Squid Game is splashed across Netflix’s Facebook and Twitter pages, which have a combined 91 million followers. Sarandos also plugged the series this week at an event where there was a good chance the press would write about it.

In the past, Netflix has been reluctant to provide much data about viewership of its shows that would reveal which are hits and which are duds. In a tacit acknowledgement of the criticism, Sarandos this week released a top 10 list of the company’s most popular series and films. But the new data didn’t please everyone. Some criticized the metrics used—the number of subscriber accounts that watched at least two minutes of a show, for example—as being less than illuminating. 

Still, Michael Pachter, an analyst with Wedbush Securities, told Fortune, “I don’t know how to measure success in Netflix. They promote whatever they want and nobody can audit their results.”

Wall Street analyst Rich Greenfield of LightShed Ventures was more bullish.

“Squid Game is a massive zeitgeist show resonating throughout our culture,” he said. Turning the conversation to his family as an example, he said that his 11-year old child, who hadn’t seen Squid Game, knew about it from a video by a YouTuber with nearly 7 million followers who goes by the moniker Gloom. In the video, Gloom plays games inspired by the show that have been recreated inside the video game platform Roblox. 

Greenfield sees the increased popularity of Netflix’s foreign hits as validation of its focus on local production. “Great storytelling is global and U.S. audiences will watch subtitled or dubbed content just like audiences around the world have always done.” U.S. and U.K. content no longer needs to be the sole definer of culture, he explained.

He sees Netflix’s investment in overseas content as a competitive advantage. In addition to the $1.2 billion it has spent in Korea on production over the past six years, Netflix splurged more than $1 billion in the U.K, $400 million in India, and $300 million in Mexico last year, in addition to other markets.

“There’s no company spending anywhere near the amount that Netflix is,” said Greenfield. “The ability to take content from anywhere in the world and spread it globally is uniquely Netflix. There’s a little bit happening at Amazon, but that’s really it. Netflix is far ahead of everyone else.”

Greenfield added there are other practical benefits.

“The cost of creating content in these markets is also less than it is in the U.S., so Squid Game is not only hugely successful relative to their current top series, Bridgerton, but my guess is it is at a fraction of the cost.”