Comcast Corp. on Wednesday confirmed that it is considering a move to thwart the $52.4 billion deal struck between 21st Century Fox Inc. and The Walt Disney Co. , by swooping in with a bigger offer of its own. The owner of NBC Universal said it is in advanced stages of preparing a superior bid. “Any offer for Fox would be all-cash and at a premium to the value of the current all-share offer from Disney,” the company said in a statement. “The structure and terms of any offer by Comcast, including with respect to both the spin-off of “New Fox” and the regulatory risk provisions and the related termination fee, would be at least as favorable to Fox shareholders as the Disney offer.” Disney has agreed to buy Fox assets, including its film and TV studios and international pay-TV properties, but excluding the Fox News channel, Fox Business Network, Fox Broadcasting Company and certain other assets. Comcast shares fell 1.6% premarket on the news, while Fox rose 0.3% and Disney slid 0.6%. S&P 500 futures were down 0.7%.