Jack Ma, the Alibaba Group Holding Ltd. co-founder who has largely stepped back from the company, made an appearance Saturday at an event co-organized by the retailer’s research arm.

Ma attended the final round of the Alibaba Global Mathematics Competition held in Hangzhou and spent time interacting with contestants and teachers, according to an online post by the Damo Academy.

The visit to Hangzhou — where Alibaba is headquartered — marks a rare appearance by the Chinese billionaire, who dropped out of public sight after he criticized Chinese regulators in 2020. Since then, he has been traveling outside the country and has made infrequent appearances back in the mainland.

Ma earlier this year joined the University of Tokyo’s Tokyo College as a visiting professor. A former teacher, he has also accepted a position as an honorary professor at the University of Hong Kong.

Read more: Jack Ma Joins University of Tokyo as Visiting Professor

Earlier this week, Alibaba President Michael Evans said Ma is “alive” and “happy,” CNBC reported. The billionaire is teaching and also spending more time in China, Evans added.

--With assistance from Jane Zhang.