I don’t believe the story that some fund faced a margin call. The market indexes are pretty much at or near their all time high. I don’t know the individual stocks involved but hard to believe they have diverged from the indexes all that much. Selling them on a Friday is a good choice, eliminate the risk of holding over the weekend. Lots of crazy stuff can happen.
If I had to guess, the seller thinks it is time to cash out. There will be better opportunities and other markets in the future. Cash on the sidelines is rarely a bad thing. Or maybe they want to push all in on something else. What can you buy with $10 billion? A lot of just about anything.
I don’t know if this sell off was done on the market. Am I reading this right that they’re securities that were not on the open market?