DayOne Data Centers, a Singapore-based data center operator gearing up for a multibillion-dollar initial public offering in New York, is little known to most U.S. investors. But its business is built on a much better known company: ByteDance.

The TikTok parent company accounts for nearly 70% of DayOne’s revenue, according to two people with knowledge of DayOne’s operations. DayOne, which started as a Chinese data center company’s overseas business unit four years ago, has benefitted greatly from ByteDance’s rapid global expansion through TikTok. But that has also left it extraordinarily dependent on a single customer, which the company has acknowledged creates a significant risk for its business.

Apple is preparing to release its Apple Intelligence on-device AI service in mainland China in December, ending a lengthy wait caused by regulatory hurdles, Bloomberg reported Thursday.

The planned release of Apple Intelligence in China, one of the iPhone-maker’s most important markets, comes ...