Activist investor Carl Icahn is demanding Dell Inc pay out $15.7 billion in special dividends, joining a growing chorus of opposition to founder Michael Dell’s plan to take the world’s No. 3 personal computer maker private. The billionaire investor, whose arrival on the scene typically puts companies on guard, wants the PC maker to pay $9 a share in dividends immediately from its own cash and from raising new debt. Icahn, who has a reputation for demanding aggressive changes after amassing stakes in companies, argued in a letter to the company’s board published last week that Michael Dell’s and Silver Lake’s proposed $24.4 billion buyout short-changed shareholders, undervalued the company and benefited mainly the firm co-founder himself. “We see no reason that the future value of Dell should not accrue to ALL the existing Dell shareholders – not just Michael Dell,” Icahn wrote in the letter, which Dell disclosed in a filing.