Berkshire Hathaway has increased its stakes in Japan¡¯s biggest trading houses, a move that is expected to offer support to the wider Tokyo stock market.

Shares of major trading houses Mitsubishi, Marubeni, Mitsui, Itochu and Sumitomo climbed 4% Tuesday morning in Tokyo, after filings to the Finance Ministry showed Monday that Berkshire¡¯s average holding across the stocks had increased by just over percentage point to about 9.3%.

Investors had been speculating over Warren Buffett¡¯s next move since his annual letter to shareholders said that Berkshire was looking to increase ownership in Japan¡¯s five largest trading houses ¡°over time.¡±