Elliott Management has quietly built up a more than $2.5bn stake in Japan’s SoftBank and is pushing the sprawling technology giant to make changes that would boost its share price, according to people familiar with the matter.

Founded by billionaire Paul Singer, New York-based Elliott is known as a formidable activist investor, often seeking to influence company management. SoftBank is one of Elliott’s largest bets, according to people familiar with the matter. At current prices, the investment would be equivalent to about 3% of SoftBank’s market value.