Elliott Investment Management has taken a $4 billion stake in PepsiCo as the activist hedge fund led by billionaire Paul Singer presses for changes to boost the company’s stock price.The Wall Street Journal first broke the news on Tuesday of Elliott’s position, now one of the soda maker’s biggest-ever investors, that helped lift shares in PepsiCo as high as 6%. The stock was recently up 1.9% at $151.43. 3 Elliott sent a letter to the PepsiCo board in which it laid out its aim of boosting the firm’s share ...