Software engineer Zhang Yiming started out producing apps for sharing jokes before focusing on news aggregation. That pivot proved lucrative.

The 35-year-old founder of Bytedance Ltd. is worth about $13 billion, according to the Bloomberg Billionaires Index, making him China's ninth-richest person and one of the fastest people in modern times to amass a mega-fortune. The business, founded in 2012, has more than 1 billion active monthly users across eight mobile apps, including a news aggregator powered by artificial intelligence and a video-sharing platform.

His rapid wealth accumulation is a sign that China hasn't lost its knack for creating mega-rich company founders despite a slowing economy. It also helps explain why authorities seem to be taking a more tolerant stance toward a corporate structure favored by the country's technology tycoons, most of whom have chosen to list their businesses overseas.