Investors tap mobile message craze as trading begins on Line

Though little known in the U.S., Line has enjoyed a quick surge to popularity in Japan, filling an important communications hole after a devastating earthquake and tsunami in 2011 damaged phone infrastructure.

Companies are angling to get in on the messaging craze with automated "chat bots" offering to book your plane tickets, shop for tennis shoes or send the day's weather report.

Emoji, the tiny virtual stickers attached to — or sent instead of — text messages, have become their own language.

Since its founding five years ago, Line has surged to 218 million active users, even though it's available only in a handful of countries.

On Monday, Line's initial public offering raised more than $1.1 billion, making it the biggest IPO in the U.S. so far this year, according to IPO research firm Renaissance Capital.

Line's stock debut in Tokyo and New York is a milestone event for a Korean internet industry that has typically seen little success outside the country, apart from some online games.