SoftBank Group Corp. is targeting investments of more $10 billion (¥1 trillion) in public stocks as part of a new asset management arm, far exceeding the initial holdings that founder Masayoshi Son outlined to shareholders Tuesday, people familiar with the initiative said.

The tally could reach into the tens of billions, said one of the people, all of whom asked not to be identified because the plans are private.

Son, the chief executive officer, unveiled the investment arm in a conference call to discuss earnings Tuesday. He said the unit has about $555 million in capital. However, the amount is seen as a placeholder, people familiar with the project said; 555 is slang in Japanese gaming culture meaning "go, go, go.”