In an internal message which Lightcap shared online Tuesday, the outgoing executive told OpenAI staff that it was “bittersweet to share that I’ll be moving on from OpenAI to start something new.”

Lightcap, who joined the company in 2018, spent four years as OpenAI’s chief financial officer. He then ascended to chief operating officer, where he served from 2022 until earlier this year when, amidst a shakeup of executive roles, he transitioned to lead special projects at the company. Prior to OpenAI, Lightcap also worked with CEO Sam Altman at venture capital firm Y-Combinator.

“I had the privilege of building the first versions of most of our operations and business teams – from Finance to Legal, People, CorpSec, GTM/Gov, Partnerships, and more,” Lightcap wrote in his message Tuesday. “Among the most rewarding parts of this journey for me has been watching each of these teams mature under brilliant leaders.”

In his note, Lightcap also looked ahead and hinted at a future venture while giving scant details as to what it might be.

“Over the last few months, I’ve been focused on the next horizon and what would stand in the way of mission success,” Lightcap said. “I believe there are a few important new things the world will need to get right as we enter this next period. I’ll have more to share soon, but I believe in OpenAI more than ever and am excited to help you all advance the mission from a different vantage point.”

As OpenAI preps for an IPO of industry-wide significance, the company has been undergoing a shakeup of top-level executives. In July, the company’s No. 2 executive, Fidji Simo, who led AGI development, announced that she would be stepping down. Other executives from less central areas of the company — including Bill Peebles, who formerly headed the company’s now dead video generator Sora and Kevin Weil, the vice president of the company’s Science vertical — have also recently left the firm.