Orbis Investment Management, a major shareholder of Nikko Cordial Corp, stepped up pressure on Citigroup to raise its $14 billion bid for the Japanese broker by offering to sell its stake on the open market ata higher price.

Analysts dismissed the move, which offers the shares at a price well above their current market value.

Orbis said it would immediately place an order on the Tokyo Stock Exchange to sell its entire 5.8 percent stake, adding that it believed Citigroup's offer of 1,700 yen per share for Nikko materially undervalued the company.

In a statement issued late on Monday in New York, Orbis said it would offer its 56.5 million shares in Japan's No. 3 brokerage at 1,900 yen each - nearly 12 percent above Citi's offer price and 13 percent higher than their market value.