Yahoo seeks to conceal parts of shareholder suit

Yahoo had previously disclosed the plans would give its 13,800 employees anywhere from four month to two years pay. Every $1.4 billion in severance cost theoretically would translate into about $1 per share less that Microsoft would have available to offer Yahoo shareholders.

Ballmer orally offered $33 per share, or $47.5 billion, but then withdrew the bid when Yang held out for $37 per share. Legg Mason money manager Bill Miller, whose fund is Yahoo's second largest shareholder, has publicly said he would have happily supported a Microsoft offer of $34 per share.

Friedlander's letter also indicated the redacted documents include comments that Yahoo's top executives made about the severance plans.