Tokyo

BILLIONAIRE Masayoshi Son's plan to list his cash cow Japanese telecom business is raising concern among observers that the company might stop guaranteeing the debt of its parent SoftBank Group Corp, worsening the quality of its credit.

The mobile division SoftBank Corp assures payments to investors on US$33.4 billion in bonds of its parent, which is rated junk by Moody's Investors Service and S&P Global Ratings, according to Bloomberg-compiled data.