Brad Lightcap went looking for OpenAI's first finance chief in 2018, interviewed more than 20 candidates, watched every one of them pass on the job, and took it himself. Eight years later he told staff on Tuesday morning that he is leaving to start something of his own. He goes as OpenAI carries an $852 billion valuation, a confidential filing for a stock market listing and close to a billion weekly users. His exit lands four months after he moved out of the chief operating officer's daily remit, and three months after he launched the $10 billion venture meant to be his next act inside the company.Writing on X, Lightcap said mission success "feels within sight" and that he had built the first versions of most of OpenAI's operations and business teams — finance, legal, people, corporate security, go-to-market, government and partnerships among them. He referenced "the Blip", the company's internal shorthand for the five days in November 2023 when the board fired Sam Altman and then brought him back. He promised more detail soon on what he plans to build, and said he would stay around for a few weeks. The message stopped short of naming the new venture or the field it will sit in.About The AuthorAt heart, I am a storyteller drawn to the watershed moments that bend the technology landscape. I braid narrative with data, humanise statistics, and trace the arc from first spark to world-changing impact. My reportage, features and reviews are witty, sardonic, visual and vivid, using anecdote to illuminate rather than eviscerate.