OpenAI is reportedly pushing ahead with plans to become a for-profit company, after more senior figures left the ChatGPT developer following the surprise exit of its chief technology officer, Mira Murati.

The San Francisco-based startup is preparing to change its corporate structure as it seeks $6.5bn (£4.9bn) in new funding, according to reports.

Under the changes, OpenAI will become a for-profit benefit corporation – an entity that makes profits but is committed to the social and public good – that will no longer be controlled by its nonprofit board, Reuters reported.

OpenAI declined to elaborate on the reports, but a spokesperson said the nonprofit entity would continue to exist. “We remain focused on building AI that benefits everyone, and we’re working with our board to ensure that we’re best positioned to succeed in our mission. The nonprofit is core to our mission and will continue to exist,” they said.

The nonprofit entity, and Sam Altman, OpenAI’s chief executive, will hold a stake in the for-profit business, Reuters reported.

Altman said on Thursday that the departure of Murati and two other senior colleagues was not linked to the restructuring. “That’s totally not true,” he said.

Speaking in an appearance at Italian Tech Week in Turin, he said: “We have been thinking about that [restructuring], our board has, for almost a year, independently, as we think about what it takes to get to our next stage. But I think this is just about people being ready for new chapters of their lives and a new generation of leadership.”

OpenAI was founded as a nonprofit in 2015 and four years later added a for-profit subsidiary, in which Microsoft is the biggest investor and whose returns to investors and employees are capped. On its website, OpenAI describes its structure as “a partnership between our original nonprofit and a new capped profit arm”. There is no cap on profits for a public benefit corporation.

“The existing structure of OpenAI is quite convoluted,” said Brian Quinn, a professor at Boston College law school. “If they simplify their structure in some way and have a public benefit corporation as the parent company, they can make as much money as they want.”

The ChatGPT developer is reportedly heading for a valuation of $150bn under the new fundraising, making it worth nearly as much as Uber. Apple and the chipmaker Nvidia are among the companies cited in reports as potential investors in the funding round.

OpenAI’s progress towards its goal of creating artificial general intelligence – which it describes as “AI systems that are generally smarter than humans” – has alarmed former employees. William Saunders, a research engineer who left OpenAI this year, said he quit because he “lost faith” that it would make responsible decisions about AGI, while a former leading safety researcher at the company, Jan Leike, claimed in May that OpenAI was prioritising “shiny products” over safety.

Responding to Leike’s comments on X at the time, Altman wrote: “He’s right, we have a lot more to do; we are committed to doing it.”

Reports of the corporate restructuring process, which could run into next year, came as more senior technical staff announced their departures. Murati, who was the figurehead for the May launch of OpenAI’s GPT-4o model, announced on Wednesday that she was leaving. She had spent a short time as OpenAI’s temporary CEO in November last year, when Altman was fired and then reinstated by the nonprofit board.

Hours later, two more colleagues, Barret Zoph and Bob McGrew, also quit, according to a post from Altman on the social media platform X. Zoph held the title of VP research, and McGrew was chief research officer.

“Mira, Bob, and Barret made these decisions independently of each other and amicably, but the timing of Mira’s decision was such that it made sense to now do this all at once, so that we can work together for a smooth handover to the next generation of leadership,” Altman wrote.

He added that leadership changes such as Murati’s departure were a “natural part of companies”, adding: “I obviously won’t pretend it’s natural for this one to be so abrupt, but we are not a normal company.”