Vladimir Romanov has effectively assumed control of Hearts after buying controversial outgoing chief executive Chris Robinson's stake in the club.
A Wednesday morning statement to the Stock Exchange confirmed that Romanov had increased his shareholding in the Edinburgh club to 29.9%.
Robinson remains as an advisor but ends his at-times stormy reign in charge.
Romanov aid Sergejus Fedotovas takes over as chief executive pending appointment of a replacement.
The agreement came two days before a deadline imposed by the Lithuanian businessman.
Romanov had entered into an agreement in December with Robinson, Chrysalis Scotland Limited, Pentland Securities (Holdings) Limited and New Hearts Limited to buy 19.6% of shares.
The statement said: "Vladimir Romanov is now the largest shareholder, owning 3,778,033 ordinary shares in Heart of Midlothian plc, representing approximately 29.905% of the issued share capital."
The Federation of Hearts Supporters Club secretary has welcomed Romanov's arrival.
Secretary John Borthwick told the Edinburgh Evening News: "This has been a long time coming, but it is the news we have been waiting years for.
"All Hearts fans will be absolutely delighted that Mr Robinson is finally on his way.
"This time last year, he gave us Murrayfield as the only option to Tynecastle with no plan B.
"To think how far we have come since then is remarkable. This is a defining moment in the history of Heart of Midlothian Football Club.
"There are suggestions Mr Robinson will be staying on at the club in some capacity.
"But, let's make it quite clear, the sooner he severs all ties with Hearts the better."
Buying more shares would trigger a full takeover.
But Romanov has already exerted his authority by blocking the sale of midfielder Paul Hartley to Celtic.
He also pressed for an extraordinary meeting at which shareholders instructed the board to cancel the proposed sale of Tynecastle Stadium for housing to Cala Management.
Robinson, who took charge in 1997, had argued that selling the stadium and hiring Murrayfield rugby stadium was the only way to wipe out debts already touching £20m until a more viable home can be built.
That resulted in fury among many fans and a public campaign for his removal.
Hearts' board has yet to formally cancel the sale to Cala, but Romanov has backed a report suggesting that Tynecastle can be made viable.