Singapore bank DBS said it is negotiating to buy a stake in an undisclosed mainland bank, with an eye to establishing joint-venture fund management and securities companies in China, state media reported, citing Richard Leung, the bank's China chief. DBS launched its consumer banking business on the Mainland this week, with more branches in Shanghai and Beijing to be added to its existing network in Shenzhen, Guangzhou and Dongguan later this year.