Facebook Buys WhatsApp

In 2014 Facebook paid roughly $19 billion for WhatsApp, a messaging app with about 450 million monthly users, 55 employees, and almost no revenue. On paper the price looked insane: about $42 per user for a service that charged a dollar a year, ran no ads, and made almost nothing. Critics called it the high-water mark of tech excess. Zuckerberg saw something else entirely.

This case sharpens one of the hardest calls a founder or operator ever faces: how to value an asset whose worth has almost nothing to do with its current income statement. When a competitor is quietly assembling something sticky in markets where you are weak, what is it actually worth to own it, or to keep it out of someone else's hands? Open the app to wrestle with the math Zuckerberg ran, and the bet underneath it.