Activist investor Jana Partners builds stake in Fiserv, WSJ reports

Group 1 - Activist investor Jana Partners has acquired a stake in Fiserv and is urging the company to take actions to improve its declining share price [1] - Fiserv's shares increased by 6.5% in premarket trading following the news [1] - The company's stock has experienced a significant decline, dropping over 67% in 2025 [1]