A Hong Kong-based hedge fund manager’s monster bet is paying off with the “Pokémon Go” sensation.

Seth Fischer's $1 billion Oasis Management stands to make tens of millions of dollars after a three-year campaign to push Nintendo Co. into mobile gaming. The success of "Pokémon Go," a new smartphone game part-owned by Nintendo, has boosted the Japanese company's shares by more than 50% in the past week, adding over $10 billion to its market capitalisation.