Sony Corp. was considering the sale of its music publishing business, including a partnership with Michael Jackson's estate, which owns the Beatles catalog, as recently as last month, emails released by hackers show.

The "top secret" plan was being handled in the U.S. by Sony Entertainment Chief Executive Officer Michael Lynton, Sony Corp. of America President Nicole Seligman and their U.S. Chief Financial Officer Steve Kober, according to a Nov. 21 email from Kober. The company had concluded the business had few growth prospects.

Top management at Tokyo-based Sony was concerned about the complex ownership and governance of the business, whose owners also include billionaire David Geffen and Abu Dhabi investors. Details of the sale plan, including possible terms or suitors, could not be determined. The documents were released as part of the cyberattack on Sony over its North Korea comedy, "The Interview."