An activist investor has dubbed the $24.4 billion leveraged buyout deal with its founder and buyout firm Silver Lake as being flawed.

Southeastern Asset Management owns 8.4 percent of Dell and has published a letter it sent to Dell's board of directors. The letter claims that the company's March 29 proxy statement fails to make a compelling case for shareholders to accept the $13.65 per share offer from Michael Dell and Silver Lake. The letter says Dell's special committee did not properly explore all options.

Quoting Dell's proxy statement, Southeastern said the company did not properly explain why it did not look at a buyout offer that would allow shareholders to elect whether they wanted to be paid in cash or stock.  Dell's special committee needs to negotiate now "in good faith."

Dell has received two alternative buyout proposals from Blackstone and billionaire investor Carl Icahn. It was believed that there might have even been others, and that Dell could ultimately be expected to result in superior offers. Southeastern said that despite this Dell recommended accepting the offer on the table from Michael Dell and Silver Lake.