Sullivan, along with David Gold, bought an equal share of the club in 2010. However, the 64-year-old has since purchased a further stake in the club's holding company WH Holding Limited.
That gives Sullivan 55.6 per cent of the shares in West Ham and a controlling stake in the club, with former equal partner Gold remaining on 30.6 per cent.
Sullivan purchased the further shares in West Ham from former owners CB Holding. They retain a small portion of shares, but this is now reduced to just 10 per cent.
His move was part of a deal to restructure £25.5million of the club’s bank debts. According to the last published accounts, West Ham have total debts of £30.5m.
When contacted by OMNISPORT, West Ham declined to make any further comment relating to ownership of the club.
