Upper Deck Co. had officially made a bid buy rival Topps Co. for about $425 million, a move that could undermine an attempt by former Walt Disney Co. head Michael Eisner to acquire the trading card company.

Upper Deck, a Carlsbad-based trading card and sports entertainment publishing company said late Monday that its offer values Topps's shares at $10.75 each and would expire on July 24.

New York-based Topps earlier agreed to be acquired by a private equity firm led by Eisner for $9.75 a share earlier this year, a price that was regarded as too low by many investors and was opposed by three of Topps 10 board members.

One of Topps' board members that opposed the sale to Eiser was Arnaud Ajdler, who said the price undervalued Topps and resulted from a "flawed" negotiation process.

Topps officials have noted several barriers to selling to their company to Upper Deck, including concerns over potential financing, and Upper Deck's liability if antitrust regulators don't approve the acquisition.

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