Soros' investment firm bought approximately 3.1 million Class A shares, or 7.85 percent of the total Class A shares, a filing with the US Securities and Exchange Commission (SEC) revealed.
That comprises 1.9 percent of Manchester United, when the powerful Class B shares held by members of the Glazer family, who control and direct the club, are taken into account.
Class B shares enjoy 10 times the voting rights in the company as compared with Class A shares.
After an underwhelming initial public offering on August 10, shares in the club finished Monday at $13.06, down 6.7 percent from the IPO price of $14.
Still, the club earned $233 million from the IPO, which valued it at about $2.3 billion, making it the most valuable sports team in the world.