The news comes just two weeks after Microsoft even overtook Apple to become the world’s most valuable company, although Apple regained its spot shortly afterward. The two companies, famous competitors since the dawn of the computing revolution half a century ago, have been neck and neck for the top spot in corporate America since the beginning of the year. In fact, understanding their decades-long competition is key to understanding just how instrumental Microsoft CEO Satya Nadella has been in taking the rivalry into this new, $3 trillion era. 

For years, Microsoft languished behind Apple, as the Cupertino, Calif., giant rolled out hit after hit—from the iPod to the iPhone to the Apple Watch. Microsoft risked being left behind in the industry that it helped create with the invention of Windows and Microsoft Office, both products that became bywords for computing in the 1990s as Microsoft leapfrogged the early computing giant Apple, with its trademark Macintosh desktops. As it sought to regain its luster in the new millennium, Microsoft tried to enter a series of new markets, such as phones and search, to name a few, racking up a series of flops. 

Read more: Satya Nadella returned Microsoft to the top by showing humility as CEO. Here’s how it’s done

Then, in 2014, current CEO Satya Nadella stepped into the role, revived the company’s culture of innovation, and led the company back to the mountaintop. Investors have rewarded Nadella’s turnaround, with Microsoft seen as exceptionally well positioned for the artificial intelligence boom. Its Azure cloud services division provides much of the cloud computing power that AI developers use to power their products, such as Meta’s Llama2 model. And its widely covered partnership with OpenAI means its fortunes are linked with the startup considered to be the market leader in AI. 

So far this year, Microsoft’s stock is up 7%, capping an astonishing 1,006% increase under Nadella’s leadership, according to Fortune calculations. Widely considered to be the architect of Microsoft’s turnaround over the past 10 years, Nadella pivoted the company to cloud computing and orchestrated its massive $10 billion deal with OpenAI back in 2019, years before it became a sensation with the release of ChatGPT to the public. The decision to partner with OpenAI was a masterstroke, foreseeing the AI revolution before others, and positioning Microsoft ahead of its competitors. 

The tech industry as a whole is fueling much of the stock market rally. The so-called Magnificent Seven—which in addition to Microsoft includes Alphabet, Amazon, Apple, Meta, Nvidia, and Tesla—accounted for 60% of gains on the S&P 500.