When OpenAI hired Denise Dresser from Slack to be its chief revenue officer in December, Fidji Simo, a top-ranking executive, said in a blog post that Dresser’s “experience will help us make AI useful, reliable, and accessible for businesses everywhere.”

Four months later, Dresser took on added responsibilities when operating chief Brad Lightcap left that position for a new role focused on “special projects.”

Now, Dresser, Simo and Lightcap are all gone, leaving OpenAI’s C-suite in chaos as the artificial intelligence company tries to justify its $852 billion valuation and gear up for what’s expected to be a historic IPO. Dresser announced her sudden departure on Thursday, two days after Lightcap said he was ending an eight-year stint at the ChatGPT creator to “start something new.”

The talent exodus puts even more pressure on CEO Sam Altman and fellow co-founder Greg Brockman, the company’s president, to project stability at a time when investors are already growing concerned about competition from Google and Anthropic, increased adoption of lower-cost open-weight models, and SpaceX’s volatile stock price in its first two months on the market.

OpenAI confidentially filed its IPO prospectus in June, but hasn’t provided a timeline for a future offering.

“The executives leaving OpenAI ahead of their IPO is a huge red flag,” Kevin McCormick, founder of AI startup SignAudit.AI, wrote in a post on X on Thursday. He added that Dresser likely walked away from a large pay package by leaving OpenAI after less than one year. 

“If the executives leaving aren’t being ‘made whole’ by the next company, it’s bad news for OpenAI,” McCormick wrote.  

A representative for OpenAI pointed CNBC to Brockman’s statement from Thursday, after the company named Dali Rajic, former COO of cybersecurity company Wiz, which Google acquired for $32 billion earlier this year, as its new chief revenue officer.

Brockman said that Dresser led the revenue group through a “formative period for the business,” and that Rajic “will turn what we’ve learned into repeatable execution as we build out the full system to make AI broadly useful for people and businesses.”

Dresser and Lightcap are the latest in a recent string of big-name exits. Simo, who last year left her job as CEO of Instacart to join OpenAI, said in July that she was stepping away to focus on recovery after a “severe exacerbation of a chronic illness.” Four other executives, including Kevin Weil, the vice president of OpenAI for Science, and marketing chief Kate Rouch, departed in April. Rouch left to focus on cancer recovery.

OpenAI’s financial backers were surprised by Dresser’s announcement, according to two current investors, who asked not to be named in order to speak freely on the matter. They said that chaos is part of OpenAI’s fast-moving culture. 

Dresser was hired in December after establishing a strong reputation in the enterprise by spending more than a decade in senior roles at Salesforce. She was tasked with growing OpenAI’s enterprise unit, a high-margin part of the business that’s directly taking on Anthropic.

Brockman told employees on Thursday that run rate revenue increased more than 20% month over month in July, including 32% growth for business customers, according to an internal Slack message shared with CNBC.

“We’re now at an inflection point: the next generation of models will change not just how individual workflows get done, but what it means to build and run a company,” Brockman wrote. “Our opportunity is to bring those capabilities to businesses across the economy.”

OpenAI CFO Sarah Friar plans to hold a meeting with investors on Friday, according to a source familiar with the meeting. The event had been already been planned, but Friar is expected to address the C-suite shakeup. Brockman will also be in attendance to talk about company strategy, according to the person, who asked not to be named because the details were confidential.

Despite the recent turmoil, OpenAI is touting its momentum with corporate clients. The company said Thursday that under Dresser’s leadership, the enterprise business grew to 2 million customers, doubling from a year prior.

“I just have never seen this level of conviction spread so quickly and consistently within the industries,” Dresser told CNBC in April, as she was wrapping up her first 90 days on the job. She said at the time that enterprise made up 40% of the company’s revenue and was “on track to reach parity with consumer by the end of 2026.”

Days before that interview, Dresser had been tapped to take over many of Lightcap’s responsibilities, further raising her profile at the company.

Rajic, Dresser’s replacement, was introduced to OpenAI through Thrive founder Josh Kushner, according to a person with knowledge of the matter. Thrive has been one of OpenAI’s most prominent backers.

OpenAI has long had a hire fast, fire fast culture, according to two former employees, who asked not to be named in order to speak freely on the matter. One of them described the environment as a pressure cooker. 

Instability at the top is nothing new for OpenAI, or for Altman.

In 2023, Altman was hastily removed from his role as CEO after the company’s board determined he was “not consistently candid in his communications” with them. Days later, with investors in a panic and employees threatening to leave en masse, Altman was restored at the helm.

Altman’s brief ouster, which some OpenAI employees refer to as “the blip,” has hung over him ever since. 

The incident came up repeatedly during the high-profile Musk v. Altman trial in May. Lawyers representing Elon Musk, who sued OpenAI, Altman and Brockman in 2024 over a dispute about the company’s corporate structure, used Altman’s firing as a way to cast doubt on his character, accusing him of being untrustworthy. 

“I was not trying to deceive the board,” Altman testified from the witness stand in federal court in Oakland, California.

Musk’s attorneys also pressed Altman about several OpenAI executives who raised concerns about his behavior. They included Anthropic CEO Dario Amodei, who previously served as a research lead at OpenAI. Altman said Amodei had accused him of “many things.”

At the trial, Brockman was grilled about his own reputation as a leader. Musk’s attorneys asked him about a memo that was prepared by Ilya Sutskever, an OpenAI co-founder, highlighting issues with Brockman’s performance and management. 

One lawyer asked Brockman to confirm that his management style had been heavily criticized by OpenAI employees. Brockman responded, “I certainly disagree with that characterization.” 

After three weeks of testimony, an advisory jury said that Musk waited too long to bring his suit against OpenAI and its executives, though Musk vowed to appeal the ruling.

This week’s events haven’t helped Altman’s cause.

Following Lightcap’s departure, Altman thanked his longtime colleague in a post on X, and wrote that he was “excited to work together on what’s next.”

There was no such post after Dresser’s announcement. Rather, Altman’s only comment on X on Thursday had to do with a subject that he’s generally happier to discuss: his company’s AI models.

In response to a post from OpenAI’s account about a preview to “Ultrafast mode,” the new GPT-5.6 model “at up to 14x the speed,” Altman wrote, “/ultrafast.”

WATCH: OpenAI revenue chief Denise Dresser leaving, second major executive departure in days