A sign is posted in front of the eBay headquarters in San Jose, California.

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U.S. video game retailer GameStop announced Sunday it has made an unsolicited, non-binding offer to acquire eBay for $125 per share in a cash-and-stock deal, valuing the e-commerce platform at roughly $55.5 billion .

The offer, split evenly between cash and GameStop common stock, represents a 20% premium to eBay's Friday close of $104.07, and a 46% premium to its closing price on Feb . 4 — when the gaming retail giant started building a stake in the company, GameStop said in its statement.

Shares of eBay surged as much as 13.4% in after-hours trading to around $118.…