The brief announcement to the stock exchange gave no indication of Usmanov's intentions toward the London club.
Usmanov, who formed Red and White Holdings with investor Farhad Moshiri as a vehicle to take a stake in Arsenal, acquired a 14.65 percent holding in August from the club's former vice chairman, David Dein.
Usmanov's company is now the second-highest shareholder behind Danny Fiszman, who holds a 24 percent stake.
Dein left Arsenal in April over differences with the board over investment possibilities. He then joined forced with Usmanov, and is chairman of Red and White Holdings.
Usmanov is involved in mining, telecoms and natural gas in Russia and was ranked 278th in Forbes magazine's list of the world's richest people in 2006. He also has a box at Arsenal's Emirates stadium.
According to a source in the Russian Defence Ministry, Russia started deploying elite commando units in eastern Libya. Russian GRU officers, mercenaries and advisors have arrived in Libya