Gamestop continues to target eBay and has amassed a near 10% stake in the business. (Photo by Justin Sullivan/Getty Images)

Ryan Cohen has never been afraid of taking on larger rivals. He transformed Chewy into one of America’s biggest online pet retailers, became the architect of GameStop's unlikely revival after the meme-stock frenzy, and has consistently argued that retailers need to reinvent themselves rather than simply chasing scale.

And now he has embarked on what may prove to be the most audacious takeover attempt in recent retail history.

GameStop has nearly doubled its stake in eBay to 9.8%, escalating pressure on the online marketplace after its unsolicited takeover proposal was rebuffed earlier this year, suggesting Cohen appears prepared for a prolonged battle.

According to a regulatory filing with the U.S. Securities and Exchange Commission, GameStop now owns 43.4 million eBay shares after significantly increasing its position over recent weeks. The retailer purchased 3.5 million shares before converting options covering a further 39 million shares into common stock, using cash generated from its substantial balance sheet.