Legendary US investor Warren Buffett has spent a record $44 billion buying an American rail freight company, in the largest transaction in the history of his Berkshire Hathaway holding company.

The purchase of the Burlington Northern Santa Fe Corp was agreed upon at $100 a share, paid for in both cash and stock. The purchase price includes $10 billion of outstanding debt. "Its an all-in wager on the economic future of the United States," Buffett said in the statement. Buffett added that the rising costs of oil would make rail freight more profitable against the rival truck-based freight.

Berkshire Hathaway already owned a fifth of the rail company, which is one of the few to have a nationwide network. That network was itself created by mergers. Berkshire Hathaway is based in Omaha, Nebraska, and largely concentrates on insurance and the financial sector under the leadership of the 79-year old Buffett. Berkshire Hathaway stock is priced currently at around $100,000 a share - the most expensive on the New York Stock Exchange.