Malcolm Glazer has secured a 75.7% stake in Manchester United, enabling him to take full control of the club.
United fans demonstrated at Southampton on Sunday
Exceeding the 75% figure enables the billionaire US sports tycoon to take Manchester United private and delist its shares from the stock exchange.
The move will allow Mr Glazer complete freedom at the club, without having to seek approval from other shareholders.
Manchester United fans have promised to continue to oppose the takeover, which they say is "the death of the club".
Supporters' groups have threatened to protest at Saturday's FA Cup Final at the Millennium Stadium in Cardiff.
Mr Glazer's team is expected to make a formal announcement later on Monday that he has reached the 75% figure.
At that level of shareholding, as well as delisting, he would be able to transfer a large amount of debt onto the club's books.
With a 75% stake Mr Glazer would also leave the holders of the remaining stock with next to no power.
Short of receiving copies of the company's accounts and the right to attend annual meetings, their minority shareholding would carry no influence, and Mr Glazer would be unlikely to make dividend payments.
There is a point at which Mr Glazer can make the remaining shareholders sell to him.
This would happen when he secures 90% of the outstanding shares not owned by him at the time he makes a formal offer for the club - an offer that has not yet been made.
In the past two years the share price of the club has steadily risen as Mr Glazer has bought up chunks of stock, forcing him to pay more for each tranche in the club.
The steadily rising stock price culminated in the premium £3 a share he paid for the 28.7% Cubic Expression holding and other shareholdings last week.
Some experts believe Mr Glazer may have paid too much, with Sir Alan Sugar, the Amstrad boss and host of BBC television's The Apprentice, saying Mr Glazer had paid a "very full price".
He added: "I can't see from my point of view why it is such a good business deal."
Premier League chief Richard Scudamore has played down suggestions that Mr Glazer may now try to break out of a collective TV deal to start raising more cash at Man Utd.
United fans have threatened that the FA Cup Final could be a busy day for police and stewards.
TIMELINE OF A TAKEOVER
March 2003 - Glazer buys 2.9% stake in club
March 2004 - Glazer says he has "no current intention" of making a bid
June 2004 - Glazer's stake in club nears 20%
October 2004 - United confirms bid approach from Glazer, as his stake nears 30%
November 2004 - Glazer ousts three directors from United's board
December 2004 -Glazer makes revised bid
February 2005 - He makes new bid approach, valuing United at £800m, the club later opens its books to the tycoon
14 April 2005 - Glazer moots £800m bid for club
28 April 2005 - Takeover Panel sets 17 May deadline for Glazer to announce whether he intends to buy United
12 May 2005 - Glazer launches formal takeover bid for United after upping his stake in the club to almost 57%
13 May 2005 - Glazer says he owns 74.81% of the club.
Shareholders United vice-chairman Oliver Houston told the Observer there was "an appetite for creating pure pandemonium".
Demonstrations at the club's game at Southampton on Sunday were not on the scale expected, but some fans displayed banners.
There were three arrests and one black banner read "you were my life, goodbye Manchester United football club, RIP".
Anti-Glazer chants were also heard at the game, which was overshadowed by the home team's relegation from the Premiership.
The Independent Manchester United Supporters Association has said this weekend's FA Cup Final will be used to mourn the "death of the club".
Supporters say the club, which became a plc in 1991, will be saddled with huge debts because of the way the takeover has been financed.
Some pundits believe Mr Glazer will start to look into the Premier League's TV bargaining arrangement, which is due for renewal, in an effort to increase the club's profitability.
The clubs currently makes about £50m a year from the collective agreement, but that could increase if they were allowed to negotiate independently.
To make a change, Mr Glazer would need another 13 clubs to side with him on the issue.
Mr Scudamore told BBC Radio Five Live's Sportsweek programme: "The Premier League is blessed with a very conservative constitution. Fourteen clubs out of 20 need to vote to do anything.
"So it is almost impossible, and we have seen it in the past, for a small group of clubs to come along and achieve an alteration to what has been a very successful formula, both in terms of the way we do the TV deals and also the way we distribute the money."
Campaign group Shareholders United has urged supporters to stop buying club merchandise and the products of sponsors, such as Vodafone, Nike, Anheuser-Busch and Audi, if the club changes hands on Monday.
The group said its membership had increased to 30,000 from 20,000 in the last few days.