The Associated Press reports that the dramatic move - which means that Glazer now owns more than a quarter of the club's shares - came just hours after Manchester United confirmed that Glazer was the investor who made a preliminary takeover bid.
Glazer, who already owned 19.2 per cent of the club, increased his stake to 25.5 per cent, according to Glazer's associates in Britain, speaking on condition of anonymity.
The shares were purchased at a cost of around $81.1 million, but not from the club's largest shareholders, Irish racehorse owners John Magnier and J.P. McManus, the associates said.
Magnier and McManus own 28.89 per cent of the club through their company, Cubic Expression.
The Glazer family is required to make a statement to the London Stock Exchange today.
The Glazer family and the two Irishmen now own more than half the club. If either party reaches 30 per cent ownership, stock market rules require a formal takeover bid.
