Brad Lightcap, one of OpenAI’s longest-tenured executives, is departing the prominent AI lab to "start something new."

In an internal note shared publicly on Tuesday, Lightcap told OpenAI staff that it was "bittersweet to share that I’ll be moving on from OpenAI to start something new."

Lightcap joined the company in 2018 and spent four years as its chief financial officer. He then moved up to chief operating officer, a role he held from 2022 until earlier this year, when a reshuffling of executive responsibilities led him to oversee special projects. Before his time at OpenAI, Lightcap worked alongside CEO Sam Altman at the 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 Tuesday message. "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, hinting at a future endeavor while offering few specifics. "Over the last few months, I’ve been focused on the next horizon and what would stand in the way of mission success," he 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 prepares for an IPO that could have major implications across the industry, the company has been experiencing a wave of high-level executive departures. In July, Fidji Simo, the company’s second-in-command who led AGI development, announced she would be stepping down. Several other leaders from less central divisions have also recently left, including Bill Peebles, who previously headed the now-discontinued video generator Sora, and Kevin Weil, vice president of the company’s Science vertical.