Disney has agreed to pay $52.4bn for Fox, but Comcast said it was in the "advanced stages" of preparing a better bid.
Mr Murdoch's entertainment empire, 21st Century Fox, a year ago agreed to sell its film and television studios, its pay-TV operations including its stake in Sky, and a clutch of other assets, to Disney.
Any offer would be "all-cash and at a premium" to Disney's all-share offer, Comcast said in a statement.
According to United States of America today, while Comcast has not confirmed a number for the bid, earlier reports estimated that it to be about US$60 billion for Fox's studios, its one-third stake in Hulu, Fox's 22 regional sports networks and its stake in UK-based satellite TV and Internet provider Sky. Fox shares gained 1.6% to $37.88 on moderately increased trading volume.
After the Justice Department sued to block AT&T (T) from buying CNN parent company Time Warner (TWC), a Disney-Fox or a Comcast-Fox deal would nearly certainly face antitrust scrutiny. Fox's assets would help both companies achieve these goals, said Paul Sweeney, an analyst at Bloomberg Intelligence. Its chief competitors? Disney and Fox, naturally.
The only reason Comcast is signaling an offer but not actually making one is that it is waiting on the all-determining decision expected June 12 in the AT&T-Time Warner antitrust case. If Disney ups its offer for Fox, then that could trigger a bidding war for the studio's assets.
Fox's stakes in European satcaster Sky and Hulu are also in Comcast's sights, as well as a 50% stake in Endemol Shine Group, and a bevy of regional sports networks. Disney also is interested in owning Sky. Fox would hence be looking for the offer's value, whether it is cash or stock (with cash having more immediate value) and whether the suitor will understand Fox and be able to manage the mega deal's inevitable people and structure issues.
Comcast's plans for Fox, meanwhile, may hinge on the fate of another deal: AT&T Inc.'s attempt to acquire Time Warner Inc.
Earlier this week, Comcast's bid for Sky was given a boost when the culture secretary said he was "minded not" to refer it to broadcasting regulator Ofcom to assess any potential public interest concerns. If either deal holds, and all goes well with the Justice Department and Fox shareholders, the entire entertainment landscape is primed for some big changes in 2018, and beyond.