Shares in Peppa Pig owner Entertainment One rose 33% to a record high on Friday.
That saw its value surpassing the $4 billion price tag agreed with US toy maker Hasbro, in a sign that investors see a chance of a counter offer.
The deal agreed by the Nerf and Power Rangers-maker was four times the £1 billion ($1.22 billion) takeover offer which eOne rejected from UK commercial broadcaster ITV in 2016 as undervaluing the company.
Some analysts, however, suggest the deal may not be cast in stone, questioning how the part of eOne's business that is not aimed at infants and preschoolers will fit in with Hasbro's offering of children's toys or dolls.
Entertainment One also distributes movies aimed at an adult audience in a number of markets, which might make its film production and distribution arms of interest to Disney or another leading company in a media and streaming sector that is deep in flux, according to analysts.
"The big question you should now be asking is whether someone else will make a bid for Entertainment now it is in play," said Russ Mould, investment director at AJ Bell.
"It wouldn't be surprising to see Amazon, or Netflix want to throw their hat in the ring given how Entertainment One has such a big library of content which they need in order to keep customers loyal to their streaming platforms," he said.
Under the deal, yet to be approved by shareholders, eOne investors will receive 560 pence per share, a premium of 26.4% to Thursday's close.
Entertainment One's shares rose as high 591 pence on Friday, indicating investors thought the value of the shares could yet prove higher.
The company, which started life as a Canadian record and tape retailer, recently signed a multi-year production deal with award-winning producer Mark Gordon, who has worked on "Saving Private Ryan" and "Grey's Anatomy".
It would make sense for Hasbro to buy eOne for the family and brands division, said Fiona Orford Williams, director and media analyst at Edison Group.
It is less clear how the film, TV and music division fits in with the enlarged Hasbro group, she said.
"I am trying to imagine Mark Gordon for example, fitting into a large portion of Hasbro and I'm struggling," she said.
Analysts said another ITV bid for eOne was unlikely, given its lack of deep pockets. ITV's shares were 4.7% higher, taking the second spot on the bluechip index.
ITV, Amazon, Disney and Netflix did not immediately respond to requests for comment.