Time Warner Inc. said on Wednesday that it had rejected an unsolicited $80 billion bid by media mogul Rupert Murdoch that would have given shareholders a significant premium and created a media-and-entertainment behemoth.

The New York operator of Warner Bros. in Burbank said it rejected an offer of 1.531 of 21st Century Fox common shares and $32.42 in cash for each Time Warner share. The offer totaled about $86.30, which amounted to a premium of about 22 percent over Time Warner’s closing share price on Tuesday.

“The board is confident that continuing to execute its strategic plan will create significantly more value for the company and its stockholders and is superior to any proposal that 21st Century Fox is in a position to offer,” the company said in a prepared statement.

In turning down the offer, the board decided that Time Warner’s existing portfolio of networks and its film studio and television production business has the ability to significantly grow organically. It also doubted the ability of 21st Century Fox’s ability to manage the combined company, as well as regulatory risks in completing the deal, according to the statement.

Shares in Time Warner skyrocketed on the news, closing up $12.12, or about 17 percent, to $83.13 on the New York Stock Exchange.

Despite the rejection, media reports portray Murdoch as committed to buying out Time Warner and unwilling to walk away. The New York Times speculated that with the disclosure of the acquisition offer, Time Warner shareholders may pressure Chief Executive Jeff Bewkes to begin talks with Fox.

San Fernando Valley operations of Time Warner include Warner Bros. Entertainment and Studio in Burbank, the headquarters for the filmed entertainment, home entertainment, interactive, consumer products and DC Entertainment divisions; and Cartoon Network Studios in Burbank, owned by the Turner Broadcasting System of Time Warner.

21st Century Fox was created in 2013 after being spun off from Murdoch’s News Corp. The company operates the 20th Century Fox Film Corp. and Studio, in Los Angeles, the Fox Television network, and other global media assets.