Warren Buffett’s Berkshire Hathaway has become a major shareholder of Mitsui after raising its stake, the latest bet that Japan’s trading houses will remain attractive.

The U.S. investor increased its holdings in Mitsui to more than 10% on a voting-rights basis, and may consider expanding its stake even further, according to a statement from the Japanese company Monday.

Mitsui’s stock extended its morning gains to rise as much as 2.2% after the announcement. Fellow trading houses Mitsubishi, Itochu, Marubeni and Sumitomo were also up in Tokyo on Monday.

Buffett first revealed stakes in Japan’s top five trading houses, also known as sōgō shōsha, in 2020. Shares of the companies — which are involved in a wide range of businesses from liquefied natural gas to salmon farming — have benefited from the endorsement, outpacing the local Topix index.

Berkshire originally planned to keep its stakes below 10%, but the Japanese firms agreed to "moderately” relax the ceiling, according to Buffett’s annual investor letter from February. Berkshire has also raised its stake in Mitsubishi above the 10% threshold.

While Monday’s news isn’t surprising after the Mitsubishi stake increase, "the fact that the ‘god of investing’ is buying more is a tailwind for Japan’s trading house stocks,” said Ryunosuke Shibata, an analyst at SBI Securities Co.

The diversified nature of the trading houses means that they have been able to weather a period of volatile commodity prices better than overseas rivals, while also sharpening focus on shareholder returns.