Berkshire Hathaway has crossed the 10% ownership threshold in two more Japanese trading houses, Sumitomo Corp and Marubeni Corp, according to disclosures made on Wednesday by both companies.
The announcements, made during trading hours on May 7, mark the latest escalation of a Japan investment strategy that began in 2019 and now encompasses above-10% stakes in four of the country’s five major sogo shosha conglomerates.
Filings Show Steady Accumulation
Sumitomo disclosed that National Indemnity Company, a wholly owned subsidiary of Berkshire Hathaway, notified the company that its voting rights had risen to 10.05%, up from 9.30% as of March 2025. The subsidiary now holds 119,802,700 shares. Marubeni made a similar announcement, stating Berkshire’s voting rights had increased from 9.32% to 10.10%.
Shares of Sumitomo rose sharply on the news during the afternoon session in Tokyo, while Marubeni’s earlier losses narrowed following its own disclosure. The Nikkei 225 surged over 5% on the day, temporarily topping 63,000 yen for the first time in history, though the trading house disclosures came amid a broader rally driven by AI-related stocks.
A Strategy Now Spanning All Five Houses
The moves bring to four the number of Japanese trading houses in which Berkshire holds above 10%. National Indemnity raised its stake in Mitsubishi Corp above 10% in August 2025, followed by Mitsui & Co shortly after. Itochu Corp confirmed in March 2026 that Berkshire’s stake had reached 10.07%. Only the pace of further accumulation remains unclear.
Warren Buffett originally agreed to cap Berkshire’s ownership at 10% when he first invested in 2019, but the five firms agreed to “moderately relax” that ceiling, as Buffett disclosed in his 2024 shareholder letter. Berkshire’s total outlay on the five positions was $13.8 billion; the portfolio had grown to nearly $40 billion by early 2026.
Under New Leadership
The disclosures came days after Berkshire’s annual shareholder meeting on May 3 in Omaha, the first led by CEO Greg Abel, who took over from Buffett earlier this year. Abel used the meeting to stress continuity with Buffett’s approach, ruling out a breakup of the conglomerate. Buffett, who remains chairman, has said repeatedly that Berkshire will hold the Japanese positions for decades.
The Japan bet has also expanded beyond trading houses. In March 2026, Berkshire took a $1.8 billion stake in insurer Tokio Marine Holdings, forming a decade-long reinsurance partnership.
