Red and White Holdings first invested in Arsenal two years ago when they bought the 14.65% holding of former vice-chairman David Dein.
The company owned around 24% before making their latest move, which was confirmed in a statement from Arsenal Holdings yesterday.
If the stake was to reach 30%, the company could launch a formal takeover bid.
Arsenal’s board of directors have remained steadfast in their determination not to sell out for some time.
Their “lockdown” agreement means no director can sell their holding before April and thereafter must give each other first option.
The situation changed in December, however, when Lady Nina Bracewell-Smith was forced off the board, consequently freeing her 15.9% holding from the agreement.
A further 12.4% is owned by American businessman Stan Kroenke but he has aligned himself with the directors having accepted a seat on the board.
The other major shareholder is Daniel Fiszman, who owns a 24.11% stake.
Usmanov is a Russian oligarch of Uzbek origins with a fortune of an estimated $4.5 billion (€3.5bn).
A statement from Red and White Holdings confirmed the company now held a stake “in excess of 25%” in Arsenal.
It continued: “We are pleased to have now secured over a quarter of the shares of Arsenal.
“We are committed long-term investors and supporters of the club and are comfortable that we are now in a protected position.
“We also welcome the strengthening of the squad and look forward to a successful conclusion to the season.”