The IronSource founders sold an ad tech company for $4.4 billion. Their next bet is that AI agents will replace the ad buyers their old company served.

Zyg, the agentic e-commerce platform built by five IronSource co-founders, raised $60 million at a $500 million valuation led by Accel, just two months after emerging from stealth with a $58 million seed round. The company automates advertising, retention, support, and inventory forecasting for DTC sellers using AI agents that operate autonomously on platforms like Meta. The structural irony is that the team that built IronSource’s ad tech infrastructure for human media buyers is now building agents designed to replace them.

The founders of IronSource spent a decade building tools that helped mobile app developers monetise their products through advertising. They sold that company to Unity for $4.4 billion in 2022, watched Unity dismantle the ad network they had built, left in 2024, and have now returned with a company whose premise is that the entire category of work IronSource supported, the human management of digital advertising campaigns ...