Simo will transition from her top job at Instacart “over the next few months” and join OpenAI “later this year,” according to an OpenAI blog post.

“Fidji is exceptional,” Altman said on X Thursday morning. “We have worked together on OpenAI for the past year and I have observed her deep commitment to our mission. I cannot imagine a better new team member to help us scale the next 10x (or 100x, let’s see).”

In October 2024, Simo spoke with Fortune editor-in-chief Alyson Shontell about AI, and its ability to move the needle in industries like health care.

“I think with AI, we’re going to have way more ability to connect a lot more data, to mine that data to find better insights, and then to use those insights to tell people how to change their behavior,” she told Fortune.

Originally from a small port city in southern France, Simo was notably the first member of her family—comprised mostly of fishermen—to graduate from high school. Simo told Marie Claire in 2019 she would get “atrociously seasick” every time her father tried to take her out onto the water. When she was 20 years old, she interned as a lobbyist for the fishing industry one summer, where she grew accustomed to being one of the only women in the room.

“At meetings, it was just me plus old, retired fishermen,” she said.

After earning a master of management degree from the esteemed HEC Paris business school, Simo spent four years at eBay before joining Facebook in 2011 to help lead the advertising program for the company’s News Feed. In 2014, she was promoted to director of product development, helping spearhead the company’s mobile-ad products, and in 2019 she became head of the Facebook app. She oversaw the News Feed as well as Marketplace, Ads, Groups, Video, Stories, and more.

In January 2021, Simo joined Instacart’s board of directors, and just seven months later, she was named CEO, replacing Apoorva Mehta. She helped the company lead a successful IPO in September 2023.

While Simo proved her success as a businesswoman over the years, OpenAI’s desire to bring her on to lead AI applications makes more sense when you consider her passion for applying artificial intelligence to health care.

Simo founded the Metrodora Institute in 2023 after suffering from symptoms for years—particularly fainting and feeling weak, as she told Fortune in 2021—but was misdiagnosed by doctors and neurologists who passed off her symptoms as a byproduct of being “a tired mom.” After going to the Mayo Clinic, however, she was diagnosed with postural orthostatic tachycardia syndrome, or POTS, a lesser-known disorder that affects the nervous system.

Simo told Fortune‘s Alyson Shontell at the Most Powerful Women Conference last October that after years of pursuing a proper diagnosis for what she was experiencing, she “realized the level of research on these conditions was absolutely appalling” and felt the need for a more holistic approach to treating rare and complex diseases.

“In 2020, I was kind of falling apart from head to toe,” she said. “That seemed very terrifying that I would be diagnosed with a chronic illness—that’s incurable—and that there was pretty much no research being done to explain the biology behind these conditions. So I set out to create Metrodora, which is essentially the idea of partnering with patients to enroll them in research and gather all the 360 data points on them. We look at their genetics, we look at their immune profiling, we look at their reported symptoms, we look at their environment.”

Simo said she believes the current health care system that treats people “as a set of body organs” is not well-suited to treat chronic diseases because “all of these systems interact together.”

“You go to a cardiologist for your heart, and the gynecologist thinks you’re just a giant walking uterus,” she said at the MPW conference. “The beauty of AI is in the past, these data sets were very siloed, and even if you wanted to analyze a ton of genomics data, that was a huge endeavor that could take many months, let alone if you wanted to do it across all the data points I mentioned. But now, because we have these tools that allow us to analyze giant data sets, we’re going to be able to understand patterns we couldn’t understand before.”

While OpenAI hasn’t specified the projects Simo will work on once she joins the company as CEO of Applications, company boss Altman did say she will “focus on enabling our ‘traditional’ company functions to scale as we enter a next phase of growth.”

“This organization has the potential of accelerating human potential at a pace never seen before,” Simo said in a statement, which Altman re-shared in a blog post. “I am deeply committed to shaping these applications toward the public good.”