Sources: Elliott Management has taken a "sizable" stake in Twitter, nominated four directors to Twitter's board, and seeks to replace CEO Jack Dorsey (Bloomberg)

Bloomberg:
Sources: Elliott Management has taken a “sizable” stake in Twitter, nominated four directors to Twitter's board, and seeks to replace CEO Jack Dorsey  —  - Elliott has nominated four directors for Twitter's board  — Hedge fund has had ‘constructive discussions’ with company