SoftBank Group Corp.'s founder Masayoshi Son said he has $80 billion in cash to buy back more shares and continue investing in both private and public companies. "If our shares drop down, I will buy back more shares more aggressively," the chief executive officer said at the New York Times DealBook conference Tuesday. "We have $80 billion in cash at hand." After a record fall in its share price in March, SoftBank unveiled plans to offload ¥4.5 trillion ($43.2 billion) in assets and buy back ¥2.5 trillion of its own stock. The idea of going private through a buyout has been discussed within SoftBank for at least five years, but Son declined to comment on whether he would take his company off the stock market.