Greenspan was chairman and chief executive of Intermix when it created MySpace.com. He has said that the deal defrauded shareholders of Intermix Media of tens of billions of dollars and has called for an inquiry into the deal by the US financial regulator, the Securities & Exchange Commission, and the US Department of Justice.
A website outlines Greenspan's objections to the News Corp acquisition, accusing Richard Rosenblatt, chief executive of Intermix at the time of the acquisition, of withholding information about MySpace's prospects.
He alleges that shareholders were "blatantly misled into voting for a quick and unfair sale to News Corp".
"Rosenblatt knew before the transaction that MySpace was well on its way to becoming worth at least $20bn," Greenspan says on his website.
He cites evidence such as an email sent by Rosenblatt to Fox Interactive president Ross Levinsohn saying: "This is your show and I am looking forward to supporting the 20B dream."
The value of MySpace has undoubtedly rocketed since it was acquired in 2005, although earlier this week Viacom chairman Sumner Redstone speculated that value had tripled to about $1.5bn.
At the time News Corp bought MySpace, commentators questioned how it would parlay the huge traffic on the site into revenue.
In response to the allegations, News Corp spokesperson told Reuters: "We've strategically built this business since the acquisition and are just now beginning to realise real financial value. This is simply a case of sour grapes making for loud complaints."
Greenspan is hoping that the transaction will be "unwound" and that MySpace will become independent again.
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