Billionaire investor Warren Buffett's Berkshire Hathaway has raised its stake in Japan's top five trading firms to around 9%, it said in its annual report.

Berkshire Hathaway's wholly owned subsidiary National Indemnity Company previously held about 7% to 8% in Mitsubishi, Itochu, Mitsui & Co., Sumitomo and Marubeni, according to filings made in June.

Berkshire first announced its stakes in the trading houses in 2020 with the intention of holding them long-term and increasing them to as much as 9.9%.

Bershire Hathaway said in the report, dated Feb. 24, that it paid ¥1.6 trillion ($10.63 billion) for the five stakes, which were valued at ¥2.9 trillion at the end of 2023. In dollar terms, that translated to unrealized gains of 61% or $8 billion, it said.