It did not disclose the price of the offering. Based on Monday's closing price of $25.03 a share, the stake is worth around $607 million, according to Reuters calculations.
Yandex will not receive any proceeds from the offering, it said in a statement.
Morgan Stanley, Deutsche Bank and Goldman Sachs are acting as joint bookrunners for the offering and have been granted an option for 30 days to purchase up to an additional 2.4 million shares.
In a separate statement, Yandex also said its board approved a share buyback program in respect of up to 12 million shares - or 3.7 percent of the total - to run between the completion of the secondary share sale and at least November 14, unless extended.
Yandex raised $1.4 billion in an oversubscribed initial public offering in New York in May 2011 that was priced at $25 per share.