Morgan Stanley will take a 30 percent stake in Mitsubishi UFJ Financial Group Inc.'s Japanese wealth-management business in the latest partnership between the two banks, a source said.

Mitsubishi UFJ, which owns 22 percent of Morgan Stanley, will continue to run the business, which offers investing services to wealthy individuals in Japan, said the source, who asked to remain anonymous because the deal hasn't been announced.

New York-based Morgan Stanley will provide research and investment products when the partnership takes effect in January, the source said. Terms of the accord weren't immediately available.