Sony Corp. investor Daniel Loeb, pressing the case for an initial public offering of the company's entertainment unit, has leveled new criticism at management of the company's film and television studio.

Sony Pictures Entertainment "is characterized by a complete lack of accountability and poor financial controls" under U.S. Chief Executive Officer Michael Lynton and Amy Pascal, the studio co-chairwoman, Loeb's Third Point LLC said Monday in its quarterly letter to investors.

Loeb's latest salvo comes as the Tokyo-based company prepares to report first-quarter results this week. While Chief Executive Officer Kazuo Hirai has improved the struggling electronics business, Sony does not sufficiently address entertainment issues such as the movie flops "After Earth" and "White House Down" with investors, Third Point said.