Racehorse tycoons John Magnier and JP McManus have increased their shareholding in Manchester United plc.
Their Cubic Expression company announced to the Stock Exchange they have bought another 3.26m shares, which takes their holding to over 66.5m.
Takeover speculation has persisted since they began to increase their holding and is unlikely to subside now they own 25.49% of the club.
United boss Sir Alex Ferguson is in a legal wrangle with Magnier.
The Old Trafford boss is in dispute with the Irishman over ownership rights of the highly successful stallion Rock of Gibraltar.
Magnier and McManus are United's biggest shareholders, ahead of US sports entrepreneur Malcolm Glazer who recently increased his stake to 14.31%.
An investor who builds up a 30% equity stake in a British company is required to make an offer to all other shareholders, according to Takeover Panel regulations.