Hedge fund Jana Partners has bought up nearly three millions shares, sending stock as much as two per cent higher in early trading in New York.
The stake was revealed in a filing by Jana with the SEC in which its long positions were declared.
Barry Rosenstein, founder and managing partner of Jana, successfully pushed for a buyout of US pet shop PetSmart and Safeway. He famously cut his teeth with Asher Edelman, the inspiration for Gordon Gekko's character in the film Wall Street.
The investment raises the prospect that it could push for chief executive Jack Dorsey to make changes.
It comes after the social network attempted to sell itself, however, firms such as Salesforce eventually declined to bid bringing the prospect of a sale to a halt.