Three months. That is how long it took for a company that had just raised USD 220 million to lose three of its five founders. In August 2024 H announced on LinkedIn that Daan Wierstra, Karl Tuyls and Julien Perolat were leaving, putting the company in the hands of Charles Kantor as CEO and Laurent Sifre as CTO.
It was an awkward way to start. H had been unveiled in the spring as a Paris answer to the American AI labs, with a seed round big enough to rival companies many years older and backing from names reported to include Amazon and the Arnault family office. The pitch was frontier-scale research on agents, software that does not just answer a question but operates a browser or a computer to finish a task.
It was a clear signal: the company wanted to be judged on working software, not on its founding drama.
The departures were attributed to operational differences. The stake was a large pile of other people's money and a promise to build something worthy of it.
The remaining team kept shipping. In November 2024 H launched Runner H, an agent platform, alongside testing and web-browsing agents under the Tester H and Surfer H names. It was a clear signal: the company wanted to be judged on working software, not on its founding drama.
But the shake-up was not over. In June 2025 Gautier Cloix, a former head of Palantir France, took over as CEO from Kantor, saying he wanted to steady the ship and scale in the way Palantir had. Other departures followed through the year. In May 2026 Laurent Sifre, the last of the founding pair, stepped down as CTO and took a non-operational role as head of the scientific council.
What almost nobody predicted at the time of the round was how little the founding team would be intact by the second anniversary. A founder who raises at that scale in a hot field sets expectations that the company, not the cap table, has to meet.
The lesson is a hard one for first-time founders. Money can assemble a brilliant team, but it cannot settle how the team will work together. Agree on who decides what before the cheque clears, because afterwards every disagreement is public.