Sept. 30 (Bloomberg) -- Electric Power Development Co., Japan's biggest power wholesaler, rose the most since 2004 after it increased its first-half net income estimate by 65 percent on lower-than-expected fuel prices.

The stock climbed 7.3 percent to close at 230 yen, the biggest gain since the company listed in October, 2004. The benchmark Topix index lost 3.6 percent to 1,087.41, the lowest value since Dec. 13, 2004.

J-Power, as the Tokyo-based company is known, estimated profit of 36 billion yen ($345 million) for the six months started April 1, compared with the 22 billion yen it predicted earlier, it said yesterday. The company left its full-year profit forecast unchanged at 42 billion yen. J-Power expects sales of 366 billion yen, up from the 343 billion yen predicted earlier.

``The market is all trading down, and J-Power is the only one that had positive news today,'' said Hirofumi Kawachi, an energy analyst at Mizuho Investors Securities Co.

The company has benefited from more stable supplies of coal from Australia's Newcastle port this year and having built up large stockpiles of the fuel

To contact the reporter on this story: Megumi Yamanaka in Tokyo at myamanaka@bloomberg.net.

Last Updated: September 30, 2008 02:32 EDT