Tech giants Apple and Google announced Monday a multi-year partnership that will see Apple’s next-generation artificial intelligence features, including its Siri assistant, be powered by Google’s Gemini technology.

The collaboration marks a significant shift for Apple, which has traditionally developed its core technologies in-house.

A joint statement said Apple had selected Google’s AI technology after a “careful evaluation” determined that it provided “the most capable foundation” for the iPhone-maker’s AI ambitions.

The announcement represents a rare alliance between two companies that have long competed in the smartphone market, where Apple’s iOS and Google’s Android operating systems dominate globally.

However, the two rivals have maintained a lucrative partnership for years, with Google paying Apple billions of dollars annually to remain the default search engine on iPhones and other Apple devices.

That arrangement has faced scrutiny from regulators, with the US Department of Justice arguing in an antitrust case that the deal helps Google maintain its search monopoly, though a judge said the arrangement could continue.

Tesla boss Elon Musk, who owns his own AI company xAI, slammed the latest arrangement as anti-competitive. He called it “an unreasonable concentration of power for Google, given that they also have Android and Chrome.”

Apple reportedly had also considered partnerships with OpenAI, Anthropic, and Perplexity.

Financial details of the AI arrangement were not provided as news of the deal sent Google-parent Alphabet’s share price above a $4 trillion threshold for the first time.

Dan Ives of Wedbush Securities said the partnership was “a major validation moment for Google” and “a stepping stone” for Apple to get its AI strategy on track into 2026 and beyond.

Apple is largely perceived to have stumbled in efforts to roll out AI capabilities across its products. In December, it announced that the head of its artificial intelligence team was stepping down.

Last year, the company co-founded by Steve Jobs delayed the release of an improved Siri digital assistant, and is now promising it for later in the year.

Google, Microsoft, OpenAI and other tech rivals have been releasing ever-improved AI models and features in a fierce race to lead the sector.

Despite the collaboration, Apple emphasized that its in-house AI system, Apple Intelligence, would be used to power its iPhones and iPads at the device-only level, maintaining what it described as “industry-leading privacy standards.”