MEXICO CITY (AP) — Apple co-founder Steve Wozniak remains hospitalized in Mexico City following a “health problem” while he was in the city to speak at a business conference.

A source close to the conference who requested anonymity because they were not authorized to speak about the incident said Wozniak was stable, but declined to provide details of what had happened.

Wozniak had been scheduled to speak at the World Business Forum in Mexico City, a two-day gathering billed as the world’s most important management event.

Wozniak had been scheduled as the conference’s closing speaker Wednesday afternoon.