Sumitomo Mitsui Financial Group Inc. is raising its stake in Jefferies Financial Group Inc. and the banks will merge equity operations in Japan as their four-year partnership deepens.

Japan’s second-largest lender will increase its holding in the US investment bank to about 20% from 15% currently, though it will continue to have a less than 5% voting interest, the companies said in a statement on Friday. Sumitomo Mitsui plans to pay ¥135 billion ($912 million) for the additional stake, it said.