SoftBank Group Corp. extended a six-day slump with another drop of as much as 9% in Tokyo Monday as key companies in its portfolio delivered further bad news.

Chinese ride-hailing giant Didi Global Inc. began preparations to withdraw from U.S. stock exchanges on Thursday, shortly after the U.S. Federal Trade Commission sued to block SoftBank’s sale of Arm Ltd. to Nvidia Corp.

SoftBank founder Masayoshi Son has made significant investments in both firms and is relying on completing the Arm transaction to secure a big windfall for his investment group, valuing the sale at ¥9 trillion ($80 billion) at his most recent conference call to discuss earnings.