Mumbai: Citigroup has prepared a $14 billion final bid for Japan''s Nikko Cordial even as shares gained in volatile trading.

The latest bid for a possible takeover deal at $14 billion would be the biggest-ever foreign buyout of a Japanese firm, and while Nikko''s management has accepted the deal, Citi will take tender offers for 30 trading days.

Shares in Japan''s Nikko Cordial Corp. fell 0.3 per cent after Citigroup said it would not sweeten its $14 billion takeover bid for the brokerage a second time.

Citigroup, which is focusing on expanding its international business, began accepting tenders on Thursday. Nikko''s shares had surged after the US bank raised its offer price by 26 per cent earlier in the week, but Citigroup''s chief executive for Japan Douglas Peterson said on Wednesday the new offer was final.

"Our price is full and it''s fair and it''s firm," Douglas told a news conference. "It will not be raised."

Nikko''s stock rose ¥9 to within a yen of Citigroup''s ¥1,700 offer price immediately after the start of morning trade, but closed lower at ¥1,685 yen.

The benchmark Nikkei average rose 1.1 per cent and the brokerage sub-index ISECU gained 1.85 per cent.

Citigroup was forced to sweeten its initial bid of ¥1,350 yen after Nikko, which is facing a probe over an accounting scandal, escaped delisting by the Tokyo Stock Exchange, a development that weakened the bank''s leverage against North American investors who had dismissed its offer as too low.

The four US and Canadian investment funds that own about 25 per cent of Nikko have not commented on Citigroup''s new offer, which still falls short of the 2,000 yen a share that most of them have demanded.

Citigroup, which already owns 4.9 per cent of Nikko, is offering to buy all shares and new-share warrants tendered and is aiming for a minimum stake of 50 per cent.

Buying the rest of Nikko''s outstanding shares would cost 1.578 trillion yen ($13.5 billion), and the purchase price could rise to 1.677 trillion yen, including new-share warrants issued as part of stock-option plans.

Citigroup''s offer lapses on April 26.