Billionaire investor Warren Buffett's Berkshire Hathaway Inc. said Sunday it has acquired slightly more than 5 percent of shares in five major Japanese trading companies, including Mitsubishi Corp. and Mitsui & Co.The company is planning a long-term investment and may increase its holdings to up to 9.9 percent, it said in a news release. The three other firms are Itochu Corp., Sumitomo Corp. and Marubeni Corp.The shares were acquired over a period of approximately 12 months through regular purchases on the Tokyo Stock Exchange, it added."The five major trading companies have many joint vent…READ FULL ARTICLE