Experts believe it will take the Red Knights £1.5 billion to convince the Glazer family to sell Manchester United.
According to Wyn Grant, professor of football economics at Warwick University, it could take £500m more than the £1bn the group were planning to raise.
"The fundamental problem for the Red Knights is that the club is not for sale," Grant told the Daily Mail. "The valuation that the Glazers themselves have put on the club is £1.2bn. A price of £1bn would give them a return of about 25pc over five years, which they are unlikely to find acceptable.
"A vocal boycott by supporters is not going to fundamentally dent Manchester United's business model. Unless someone made a ridiculous offer of £1.5bn there is no guarantee that the Glazers would sell."