Aug. 7 (Bloomberg) -- Cosco Corp. Singapore Ltd., the shipbuilding and repair unit of China's biggest shipping company, fell to the lowest in 17 months in Singapore trading after saying President Ji Haisheng is stepping down today.

The stock fell 19 cents, or 7 percent, to S$2.51 as of 9:44 a.m. in Singapore, poised for its lowest close since March 2007. Ji, 56, will be replaced by Jiang Li Jun, 53, chief executive of Cosco Shipping Co., the Shanghai-listed unit of China Ocean Shipping (Group) Co., Cosco Singapore said in a statement to the Singapore stock exchange.

Cosco Singapore's shares have fallen 57 percent this year, making it the second-worst performing stock on Singapore's benchmark Straits Times Index. The company said this week that second-quarter profit rose 60 percent to a record on demand for new vessels and ship conversions.

The departure of Mr. Ji contributes to the uncertainty surrounding the company,'' said Daphne Roth, Singapore-based vice president of equity research at ABN Amro Private Bank, which oversees about $20 billion of Asian assets. ``The company has reported good earnings but there are concerns over orders and rising steel prices.''

Ji was only informed of the board's decision yesterday, the Straits Times reported today, citing the executive, who declined to say why he was leaving. Ji didn't answer calls to his mobile phone today.