Rajeev Misra, CEO of SoftBank Investment Advisors, expected dozens of Vision Fund companies to IPO in the next two years.
Alibaba BABA Sprint S would drive down the value of its portfolio, Moody's said.
Stakes in real estate startups, which make up 10% of the Vision Fund portfolio, will also be hit.
OneWeb filed for bankruptcy last week, becoming the second Vision Fund company to go bust (direct-to-consumer company Brandless was the first ).
But Son's desire to raise even more money to support the Vision Fund during this crisis still worries some analysts.