Fidji Simo, who held the second-highest executive position at OpenAI, is leaving her full-time role at the company. The news, first reported by the Wall Street Journal, was subsequently confirmed by Simo herself in a post on X.

In an internal note shared with staff on Thursday, Simo explained that her medical leave had extended far beyond what she had originally anticipated, and that the experience had been more difficult than expected. Rather than returning to her full-time duties, she said she would shift into a part-time advisory capacity.

A Role Built Around Consolidation

Simo had joined OpenAI's board of directors in 2024 before formally coming aboard as an executive in May 2025, when she was appointed CEO of Applications - a newly created position that reported directly to CEO Sam Altman. The role was designed to bring together the company's business and product functions under a single leader.

Her arrival triggered a significant reorganization of the company's reporting structure. Chief Operating Officer Brad Lightcap, Chief Financial Officer Sarah Friar, and Chief Product Officer Kevin Weil all began reporting to Simo rather than directly to Altman. With those responsibilities delegated, Altman redirected his own focus toward research, computing infrastructure, and safety.

Health Issues Disclosed Earlier This Year

Simo had first made her health situation public in April, when she announced she was taking medical leave due to a relapse of a neuroimmune condition. That same internal memo also revealed that Lightcap was transitioning into a new "special projects" role, and that Chief Marketing Officer Kate Rouch was departing the company to focus on her own cancer recovery. Kevin Weil has since also left OpenAI.

Before joining OpenAI, Simo served as CEO of Instacart from 2021, where she guided the grocery delivery company through its initial public offering in 2023. Prior to that, she spent more than a decade at Meta, where her responsibilities included leading the Facebook application.

A Leadership Gap at a Critical Moment

Simo's permanent departure leaves Altman in need of a successor at a particularly sensitive time. OpenAI has been exploring the possibility of an IPO, and Simo had been widely regarded as a strong candidate to take on an even broader leadership role once the company went public. Her exit creates a meaningful gap that Altman will need to address.

Much of Simo's focus during her tenure had been on expanding OpenAI's consumer-facing business. However, growth in ChatGPT's user base slowed toward the end of last year, with the product reportedly falling short of internal revenue targets. That shortfall prompted the company to place greater emphasis on coding tools - a segment where it currently trails competitor Anthropic.

Shortly after the Wall Street Journal's report was published, Simo shared the news directly on X. Altman also responded publicly on the platform, writing: "i am really sad about this and very grateful for all fidji has done for openai, and even grateful for her friendship and who she is as a person. we all wish her the best for a speedy recovery. this sucks."

A Busy Day for OpenAI

Simo's announcement coincided with a notably active news cycle for OpenAI. Earlier on Thursday, the company unveiled its new GPT-5.6 family of models - named Sol, Terra, and Luna - along with a new agent called ChatGPT Work. The latter is built to handle complex, multi-step workplace tasks, including drafting documents, creating spreadsheets, and assembling presentations. OpenAI framed both announcements as direct competitive moves against Anthropic.

A Lean Executive Bench

From the outside, OpenAI's senior leadership team appears relatively small for a company that was most recently valued at approximately $852 billion. Beyond Altman, the current roster includes Lightcap, Friar, and co-founder Greg Brockman, who serves as president and had been overseeing product strategy during Simo's absence. The team also includes Denise Dresser, who joined in December as Chief Revenue Officer with responsibility for the company's global revenue strategy across enterprise and customer success functions.

Given Dresser's background - which includes two years as CEO of Slack and 14 years at Slack's parent company, Salesforce - it would not be surprising if she were to take on a broader leadership mandate in the months ahead.

Equity Policy Changes Add Context

Simo's departure also comes against the backdrop of notable changes OpenAI has made to how it handles employee equity. In April of last year - the same month Simo joined the company - OpenAI shortened its vesting cliff from the standard 12-month waiting period to just six months. Then in December, the company went further, eliminating the cliff entirely for new hires and allowing equity to begin vesting from the first day of employment.

Simo had described the policy change internally as a way to allow employees to "take risks" without the concern that they might forfeit their equity if they left or were let go before the cliff period ended. The move reflected the intensifying competition for artificial intelligence talent across the industry. OpenAI was projected to spend approximately $6 billion on stock-based compensation in 2025 alone.

It is worth noting that none of the recent executive departures appear to be connected to compensation-related disputes. Executive equity arrangements are typically negotiated on an individual basis and may carry entirely different terms from those offered to general employees.