OMAHA, Neb. ( TheStreet) -- Berkshire Hathaway ( BRK.A), the investment vehicle of Warren Buffett, has bought more than 87,000 shares of oil giant Exxon Mobil ( XOM) and added 3.4 million American depositary receipts in Nestle. Buffett also almost has doubled his stake in Wal-Mart ( WMT), the world's No. 1 retailer. The stake was valued at more than $1.8 billion in September, the Financial Times reports, citing regulatory filings Buffett told the Financial Times this month that the value of most currencies would decline in purchasing power. "I still believe, over a 10-year period from now, I would much rather own stocks than cash," Buffett is quoted as saying. Buffett also picked up stakes in waste management company Republic Services ( RSG) and insurer Travelers ( TRV). Buffett's investments, as of Sept. 30, preceded by two months his $26.6 billion acquisition of railroad company Burlington Northern Santa Fe ( BNI).