Masayoshi Son has a $8.6 billion dilemma on his hands.

His SoftBank Group Corp. is the largest shareholder of Yahoo Japan Corp., controls several board seats and wields more power over the country¡¯s most profitable website than anyone. That has been possible because Marissa Mayer¡¯s Yahoo Inc., the next biggest shareholder with 35.5 percent, has been happy to leave management to the nation¡¯s second-richest man.

Now Yahoo is said to be considering asset sales, including possibly disposing of its $8.6 billion stake in the Japanese portal, which may force Son to spend money to maintain his grip on a company he already effectively controls. Those resources could be better used to shore up his struggling Sprint Corp. or other investments without adding to SoftBank¡¯s existing $109.4 billion in long-term liabilities.