SoftBank's Vision Fund writedown can't be the half of it

Slack Technologies Inc., another of Masayoshi Son’s celebrated investments, fell 38% during the same period for a loss of $504 million to the Vision Fund, the $100 billion investment vehicle controlled by SoftBank.

A DISASTROUS three months for SoftBank Group Corp. may force its Vision Fund to write down at least $5 billion for the September quarter, Bloomberg News reported. That’s not the half of it. Literally.

There are bigger, deeper, and likely unrecoverable losses ahead for the world’s largest venture-capital fund. That the devaluation of its holdings might be as low as $5 billion, possibly as high as $7 billion, according to people familiar with the matter, indicates that the Japanese company has barely scratched the surface of what losses it will need to book on its stake in WeWork, let alone the rest of its portfolio.