Who's too young for an app? Musical.ly tests the limits

New York

IN THE folklore of the startup world, few figures loom larger than the teenager. Teenagers see the future, set trends and spend money, or compel parents to spend it for them. Their behaviour has become an obsession for entrepreneurs.

This would seem to bode well for Musical.ly, an app that is young in every sense of the word. The Shanghai-based company founded in 2014 claims more than 100 million users, most of whom, the company says, are in the 13-20 age bracket. In August, the company partnered MTV for a promotion tied to the Video Music Awards.

What is striking about the app, though, is how many of its users appear to be even younger than that. Musical.ly hasn't just found the coveted teenage audience - it may have …