https://qz.com/519388/this-saudi-prince-now-owns-more-of-twi...
"Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud, who in 2011 invested $300 million in the social network, now owns 34.9 million shares of Twitter’s common stock, according to a new regulatory filing (pdf)."
That is from 2015, but as far as I know he still owns a huge stake in the company. It would seem relevant when discussing SA's influence on Twitter, but I don't see it mentioned in the article for some reason.