(Image: WHATSAPP)

Standing outside a derelict building that was once his lifeline, Jan Koum signed the deal that consigned his impoverished childhood to the history books. The last time he stood outside the run-down former North County Social Services offices in the Californian suburb of Mountain View he was queuing to collect food stamps as a teenager. But on Wednesday he went back to the boarded-up building to sign a deal to sell WhatsApp to Facebook. The instant messaging company he founded less than five years ago went for an incredible £11.4billion. The disused building is only a few blocks from the WhatsApp offices, but Jan’s life is now a world away. Today he is an estimated £4.1 billion richer thanks to his stake in the firm, said by financial magazine Forbes to be around 45%. The complex deal, with Facebook paying a mix of cash, stocks and shares, means Jan, 37, will make even more in four years. He will also sit on Facebook’s board – an incredible turnaround from the day he was rejected for a job there while unemployed. In the five years since it was founded by Jan and his former Yahoo colleague Brian Acton, WhatsApp has regularly topped best-selling apps lists and has 450 million global users per month, with more than 50 billion messages sent through it per day. Though his is one of the most remarkable rags-to-riches tales Silicon Valley has ever seen, little is known about Jan’s personal life and he is not prone to flashy gestures with his wealth. But then when you learn about his childhood behind the Iron Curtain, perhaps that’s not surprising. Born to a builder and housewife in a village near Kiev, by his own account he was a “rebellious little kid” in a home where there was no hot water and his parents rarely used the phone in case it was tapped by the oppressive Communist state. “Our school didn’t even have an inside bathroom,” he said. “Imagine the Ukrainian winter, -20°C, where little kids have to cross the parking lot to use the bathroom. —-