A four-year-old Beijing-based advertising agency, which sells time slots on China’s popular short video platforms to advertisers, began offering its shares to investors in Hong Kong on Tuesday with the aim of raising up to HK$1.1 billion (US$141 million), after it locked in tech giants ByteDance and Xiaomi as cornerstone investors. Uju Holding’s initial public offering sheds light on a rapidly expanding new business ecosystem that has grown alongside the emergence of short video platforms like Douyin, TikTok’s domestic sister app, and Kuaishou as the new entertainment venues in China. Uju Holding is registered in the Cayman Islands and its...