S4 Capital headcount down 750 in a year as its AI agents now code for two days unsupervised

S4 Capital, Martin Sorrell's advertising group, cut its headcount by about 750 people in a year, while its Monks agency now lets AI agents write code for up to 48 hours with no one watching. The company's interim results on 5 August 2026 put the workforce at about 6,150 at the end of June, down 10.5 percent from about 6,900 a year earlier, and personnel costs fell from £262.4 million to £224.2 million for the half. S4 does not credit AI for the job cuts: the results describe "reducing non-billable roles and back office efficiencies" and disciplined cost management. What its chief AI and revenue officer, Wesley ter Haar, told Digiday on 6 October is about where the work is going. Most agent work is coding on Monks' own software, where handing jobs to agents was "a bit of a no-brainer": "We had coding agents that were working for 36 to 48 hours and not making mistakes." The setup is moving into social and performance marketing, and early next year a client's social work, from insights to community management, will run on it. Ter Haar now plans spending on AI tokens out of the same pot as pay: "They are part of what I call the talent budget. That's the only place for us to put it." Asked about jobs, he said by email that Monks is "focused on how jobs change, and coordinating the work between people and agents". Because S4 has not said that AI is doing the work of the people who left, this headcount reduction is an article and not a counted AI job loss. The employer-attributed AI job cuts on record are in the AI layoffs tracker on this site.