Softbank, the Japanese telecom and ISP that bought Vodafone's Japanese business for $15.5 billion earlier this year, saw its stock fall as regulatory filings revealed Chairman Masayoshi Son lent out up to one third of his personal holdings in Softbank as collateral against loans. Investors fear that if Softbank's stock price falls too dramatically, Son's personal holdings, which typically serve to stabilize the company's shares, could end up being cut back.

For more about Softbank's falling shares:
- check out this article from the Financial Times