Shares of the largest Japanese trading houses rallied on Tuesday after Warren Buffet's Berkshire Hathaway raised its stakes in them overnight. The five companies are the biggest trading houses, in Japan and invest "in a manner somewhat similar to Berkshire itself,

National Indemnity, a wholly owned unit of Berkshire Hathaway, said that it increased its stakes in the five trading houses by between 1.0% and 1.7%.

Berkshire's stake in Mitsui & Co rose to 9.82% from 8.09%, while its holdings in Mitsubishi Corp, Sumitomo Corp, Itochu and Marubeni also rose by some percentage points, according to documents filed to Japan's securities watchdog by its unit, National Indemnity Company.