GameStop has offered to buy eBay for $55.5 billion, a move that would give the video game retailer control over a decades-old online marketplace where people can buy and sell collectibles, apparel, and other goods.

Under the takeover proposal, GameStop said on Sunday it is offering $125 per share for eBay in cash and stock. The video game company, based in Grapevine, Texas, already has a 5% stake in eBay. 

GameStop CEO Ryan Cohen said in a letter to eBay's chairman of the board that it has received a commitment from TD Securities to contribute $20 billion to help fund the deal. 

eBay said on Monday that it will "carefully review and consider the unsolicited proposal to determine the course of action that it believes is in the best interests of the company and all eBay shareholders."

The Wall Street Journal, which first reported GameStop's offer for eBay, said Cohen is prepared to launch a hostile bid if eBay rejects the deal. EBay could be a "legit competitor to Amazon," Cohen said in his comments to the Journal.

"EBay should be worth — and will be worth — a lot more money," he told the paper. "I'm thinking about turning eBay into something worth hundreds of billions of dollars."

GameStop has a market capitalization of nearly $12 billion and is far smaller than eBay, which is valued at around $49 billion.

GameStop shares fell in early trading on Monday, dropping 2% to $26. EBay's stock rose 5% to $109.72.