Sumitomo Trust & Banking Co.'s Nikko Asset Management Co. unit agreed to buy DBS Asset Management from DBS Group Holdings Ltd. for 137 million Singapore dollars ($105 million) to tap business from the expanding ranks of wealthy Asians.

Under the accord, DBS Asset will also take a 7.25 percent stake in Nikko Asset and the combined firm's managed assets will total over $150 billion, the companies said in a joint statement filed to the Stock Exchange of Singapore Monday.

Japanese banks are increasing investment in financial firms abroad to counter slowing lending demand at home. The deal would help Sumitomo Trust increase asset management for Asians outside Japan as the region's wealth expansion outpaces the rest of the world.