The Big Number: $31.5 Billion

Some 10 percent of the world’s one billion smokers have been reaching for vapes, many of which come in eye-grabbing pastel colors and eggy shapes that some young smokers have likened to toys or fashion accessories.

The write-down may sting at the moment, Mr. Marroco said, but the popularity of vapes offers a “vast” opportunity for growth, too.