The swirl of takeover talk around 21st Century Fox is only gaining steam as sources confirm Sony Pictures Entertainment has joined the list of companies making overtures to the Murdoch empire.

21st Century Fox surprisingly became a takeover target earlier this month when word first surfaced that Disney recently held talks with Fox about buying key assets including the film and TV production studios, international TV platforms including Sky and Star India and the FX and National Geographic cable groups.

In just the past few days, Comcast made an approach to Fox to discuss a similarly configured sale. Sony is believed to be looking at a select group of assets rather than the entire company. Verizon, according to a report Thursday night by Dow Jones, has also signaled its interest.

Reps for Fox and Sony declined to comment. The hive of activity around Fox is fueling a new round of M&A speculation for other media assets, including Viacom’s Paramount Pictures and its cable networks. Viacom shares were up 10.3% at the close of trading Friday, after getting socked Thursday on the heels of the company’s fiscal fourth quarter earnings report showing weakness in the domestic cable operations. Lionsgate was up 5%. Fox shares were up 6.5%, after spiking Thursday night in after-hours trading following the report of Comcast’s interest.

Sources caution that the sale discussion process within Fox is in the very preliminary stages. Sony’s query came as an informal overture expressing interest in talking if Fox should move into a more formal auction process. Sources said that Fox has yet to formally engage bankers to prepare sale-related materials and field offers. Fox on Wednesday held its annual shareholders meeting on the 20th Century Fox lot in Century City but it’s still not clear if Fox has convened a board meeting to discuss the incoming queries.

What is clear from all the activity and Fox’s lack of comment is that the Murdochs, who have firm control of 21st Century Fox, are at least willing to listen to potential sale options that would have been unthinkable just a year ago.

There is speculation that the Murdochs would move to combine the Fox broadcast network and TV stations, Fox News and Fox Sports operations, which are not believed to be part of any sale scenario, and reunite them with the publishing assets held by News Corp. 21st Century Fox was carved out as a separate entity from News Corp. in 2013 amid a scandal involving the U.K. newspaper division and concerns that the financial challenges of the publishing businesses were dragging down the value of Fox media and entertainment assets. There is also speculation that the Murdochs might use the proceeds from selling off big pieces of 21st Century Fox to take an enlarged News Corp. private.

A source close to the situation say the willingness to entertain sale offers also reflects the internal pessimism that 21st Century Fox’s pending deal to takeover the remaining 61% of European satcaster Sky will win approval from British regulators. The $15 billion deal set last December has been held up in a U.K. regulatory review for months. The assumption is that the sale talk is a sign that Rupert Murdoch and his sons — 21st Century Fox executive chairman Lachlan Murdoch and CEO James Murdoch — are taking a hard look at growth prospects of Fox under its current structure if the Sky deal does not transpire.

“We think the news further highlights an increased quest for economies of scale in a fast-changing media and telecom landscape,” CFRA analyst Tuna Amobi wrote on Friday. “Some of (Fox’s) key assets seem poised to spark a potentially robust auction, perhaps further underscoring a shifting paradigm of the overall media landscape.”