Japan’s financial regulator named Nomura Holdings Inc. and three other firms as the most systemically important domestic banks, subjecting them to an additional capital buffer.

Nomura, Daiwa Securities Group Inc., Sumitomo Mitsui Trust Holdings Inc. and Norinchukin Bank will have to raise the ratio of their capital to risk-weighted assets by 0.5 percentage point by March 2019, the Financial Services Agency said in a statement Friday.

The extra capital requirement is on top of a 7 percent buffer set by the Basel Committee on Banking Supervision to improve the health of the global financial system following the 2008 crisis. All four Tokyo-based firms already have common equity Tier 1 capital ratios above 7.5 percent, according to their financial statements.

Nomura and Daiwa are Japan’s two biggest brokerages, while Sumitomo Mitsui Trust is the fourth-largest lender by assets. Unlisted Norinchukin is the nation’s largest agricultural bank.

Japan’s largest lenders -- Mitsubishi UFJ Financial Group Inc., Sumitomo Mitsui Financial Group Inc. and Mizuho Financial Group Inc. -- have already been designated among the world’s 30 most systemically important banks. That means Mitsubishi UFJ, the nation’s biggest lender, must hold an additional capital ratio of 1.5 percentage points, and the other two are subject to a 1 percentage-point buffer.

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