EBay on Tuesday rejected an ambitious $56 billion takeover bid from the much smaller GameStop on doubts over the financing of the deal.

Ebay, whose market capitalization is four times that of Gamestop, highlighted the “uncertainty” around the “financing proposal” for the $56 billion unsolicited bid.

It’s still unclear how exactly GameStop, at a fraction of eBay’s size, would secure all the money needed for the transaction.