Markus is Co-Founder at Lyon, a Y Combinator S26 startup that builds private foundation models for banks, insurers, and fintechs. He focuses on building foundation models for event data.

Markus studies mathematics, statistics, and machine learning at Stanford University. He is a Medici Grant recipient from the 1517 Fund.

Lyon is built by a team from Stanford and NVIDIA, and Markus builds the core models that learn directly from raw customer events. He keeps a personal site at markushoehn.com.

Lyon joined Y Combinator's Summer 2026 batch and is based in San Francisco. Its models run inside the customer's own cloud, so clients keep ownership of their data and model weights.

Lyon trained a model on 28B transactions for a fintech serving tens of millions of active users. The model identified premium-card converters 4x more precisely than the fintech's existing rules and is now being deployed for credit.