SoftBank Group Corp. is considering seeking a valuation of about $90 billion for its domestic wireless business in a planned initial public offering, according to sources.

SoftBank is speaking to advisers about selling a third ¡ª or about $30 billion ¡ª of the business in the IPO, the sources said, asking not to be identified as the talks aren¡¯t public.

Discussions are preliminary and the final valuation will depend on investors¡¯ feedback, they said. SoftBank rose 6.5 percent in Tokyo on Tuesday, the biggest increase since June, following strong first-quarter results.