Berkshire Hathaway Inc. has solidified its position as the largest shareholder in the Japanese trading house Mitsui & Co., holding a 10.1% stake valued at approximately $7.1 billion as of October 19, 2025. This move is a significant step in Warren Buffett's long-term strategy of investing in Japan's five largest trading houses, which he initiated in 2020. The investment has been closely watched by the market, and previous announcements of Berkshire increasing its stakes in these companies have been met with positive stock performance for the trading houses. While specific market reaction to becoming the single largest shareholder on this date is not detailed, the continued investment by Berkshire Hathaway is seen as a strong vote of confidence in the Japanese economy and the diversified business models of companies like Mitsui. Buffett had indicated in his February 2025 annual letter to shareholders that Berkshire would likely increase its ownership in the five trading houses, and this recent development confirms that strategic direction.