Tim Cook and Mark Zuckerberg have clashed for years, but with John Ternus taking the reins at Apple, the rivals are finding common ground in artificial intelligence.

Meta and Apple revealed a new collaboration Thursday that will enable developers to easily run Meta's new open-weight AI model on Apple's high-end desktop computers.

Muse Spark Open, which the companies' collaboration centers on, is the most capable open-weight model released under a license that allows for limited commercial use, according to Meta. It's an 816-billion-parameter model using a so-called mixture-of-experts architecture. As an open-weight model, developers can download the technology's parameters, or weights, from the internet and run the model on a wide range of hardware.

Customers will be able to pair between two and four Mac Studio PCs to use Muse Spark to code, analyze video or do other agentic work. The model runs locally, instead of in the cloud, adding a layer of security and saving users money, the companies said.

Thursday's announcement, following months of collaboration, is a sign that the AI boom has shifted historical alliances in Silicon Valley. For years, Apple and Meta regarded each other warily and avoided public partnerships, and the relationship hit rock bottom after Apple introduced privacy changes in 2021 that limited the targeting capabilities of digital ad companies. Meta estimated in early 2022 that the change would cut its revenue that year by $10 billion.

Representatives from Apple and Meta declined to say if the Muse Spark Open collaboration was the start of a deeper relationship.

Meta AI chief Alexandr Wang said in an interview that many powerful open-weight models are too big to be run on the majority of personal computers, but Apple's Mac Studios make enough memory available to users so that it's practical to run Muse Spark Open.

The move represents an important show of confidence in Meta's rebooted AI efforts and could pose a challenge to OpenAI and Anthropic. It could also signal Apple's growing strength in AI chips, a market that Nvidia has dominated so far due to their prevalence in large data centers.

"We worked with Apple to bring leading Agent capabilities to your desktop for the first time on the Apple M5 Ultra Mac Studios, so you know we're really excited about this," Wang said. Developers can download a version of the AI model from websites like Hugging Face without extra configuration for Apple's silicon. Muse Spark Open has also been tuned to run faster on Apple's hardware, and the iPhone maker revealed new benchmarks for its chips and published technical documentation about its MLX AI framework's ability to split open-source models across multiple machines.

Mac Studios aren't cheap though, and this AI model requires the fastest Apple chips and as much memory as possible.

Currently, a Mac Studio with the required M5 Ultra chip and 256GB of memory costs at least $10,799. A more expensive version with 512GB of RAM will be released later this month. Plus, users will need to buy multiple machines.

The two companies are collaborating on open-source AI, which has become a point of contention in Washington as politicians worry that free Chinese models could undercut American AI. Although Meta once centered its AI strategy on its older open-weight Llama family of models, it has since focused on creating proprietary models under the leadership of Wang, who joined Meta when the company invested more than $14 billion into his former startup Scale AI last year.

While Apple and Meta, then known as Facebook, partnered on iPhone extensions over a decade ago, they haven't struck any public partnerships since 2017 after Apple removed system-level Facebook integration from the iPhone.

"Most of the animosity predates my tenure at the company, but obviously there's been a long history between Meta and Apple," Wang said, pointing to one member of his team, AI researcher and former Apple director Daniel Gross, as a reason for the collaboration. Gross, along with former GitHub CEO Nat Friedman, was a major Zuckerberg hire last year as the Facebook founder was overhauling his company's AI strategy. Their leaders have also traded harsh words.

Cook, who was Apple CEO until Ternus succeeded him last month, took a shot at Zuckerberg in 2018, during the Cambridge Analytica scandal, saying, "I wouldn't be in this situation." Cook often criticized Meta for compromising user privacy.

Zuckerberg has also insulted Apple in public, telling Joe Rogan last year that the company "hasn't invented anything great since the iPhone." Zuckerberg has long sought to find a platform that Meta can own so it's not beholden to Apple.

Ternus, a hardware engineer, has already started changing things at Apple, including when it releases products.

And Meta's developers haven't been able to resist Apple's products. The company bought hundreds of Mac computers so its Superintelligence team could experiment with local AI and agents earlier this year. Meta is just the latest AI model developer to team up with Apple.

In 2024, Apple announced a partnership with OpenAI to integrate ChatGPT into Siri, although the integration "dramatically underperformed" and didn't lead to OpenAI user growth, OpenAI said in a filing that's part of a legal dispute with Elon Musk's xAI. Apple sued OpenAI in July, alleging trade secret theft, a claim OpenAI denied.

Earlier this year, Apple announced a deal with Google, to use its Gemini models in Apple Intelligence as well as Google Cloud infrastructure.

Still, Apple's AI strategy has drawn criticism from investors and customers in part because its new version of Siri, released last month, isn't as advanced as chatbots and agents from leading labs.

Meanwhile, Meta has bet big on becoming a leading lab but has struggled to keep up with the competition and its business remains almost entirely reliant on ads. Recent developments, such as Meta's Muse personal agent app and its latest proprietary foundation model, Muse Wonder, released earlier this week, have begun to excite investors who are optimistic about new AI business opportunities.

Open source remains part of Zuckerberg's AI strategy. In August, Meta debuted a small open-weight AI model dubbed Muse Glimmer, with Zuckerberg pledging to eventually release something bigger and more powerful.

Muse Spark Open isn't as advanced as Muse Wonder, a proprietary offering, but Wang said it's good enough to potentially entice more coders to upgrade. "These aren't the most capable models that we've developed or released," Wang said.

"But we think that there will be a lot of companies and developers who sort of use this model and tinker with it at small scale and then seek to ramp up and scale up their usage."