Kim Jung-ju

Late Nexon founder Kim Jung-ju's 18-year-old daughter has become the world's youngest billionaire.

Forbes magazine on Wednesday said Kim Jung-youn inherited a 30.78-percent stake worth US$2.5 billion in the online gaming giant on her father's death aged 54 in February.

Earlier Nexon said Kim's wife and daughters inherited the founder's 67.49 percent stake of 1.96 million shares. Each of them already owned a 0.68 percent stake of 895,305 shares before Kim senior's untimely death.

"Together with the sisters' existing shares in NXC, their stakes in the company are worth $2.5 billion each," Forbes said. "After deducting their inheritance tax bill, which Forbes calculates at over $1.5 billion each... Jung-youn's and Jung-min's net worths are estimated at $1 billion each."

Korea has one of the highest inheritance tax rates in the world.

The youngest billionaire so far had been Kevin David Lehmann of Germany, who inherited a stake in German drugstore chain dm from his father.