Greenlight founder David Einhorn wrote to investors on Monday that his hedge fund had taken the position, paying an average $37.24 for the stock, according to the letter seen by Reuters.

"At this price there is a $17 per share of upside if TWTR prevails in court and we believe about $17 per share of downside, if the deal breaks. So we are getting 50-50 odds on something that should happen 95%+ of the time," the letter said.

(Reporting by Svea Herbst-Bayliss)