A few things that are missing from tom's report:
1. Softbank has 36B$ in debt but hold 227B$ in equity. And they wanted to reduced the debt, hence selling stocks or reducing funds (like 14B$ less investment in weworks for 2019).
2. Softbank bought the nvidia shares at 105$, so they still made a lot of money selling them for 218$ as they had a protection plan (granted not the same if they sold them at 294$ at peak).
3. They sold shares they hold on different companies at 23.5B$ to fund buybacks they are in the process of purchasing.