NEW YORK (CNNMoney.com) - Billionaire investor Warren Buffett is making a $14 billion bet on global stock markets, according to an article Tuesday.

Buffett's Berkshire Hathaway (Research) has sold clients insurance protection against a drop in four equity indices, the Financial Times reported.

If the indices, three of which are outside the U.S., fall by 30 percent over the 15-20-year life of the contracts, Berkshire would incur a pre-tax loss of about $900 million. It has a maximum exposure of $14 billion, according to the report.

Analysts told the paper that the purchasers of the index contracts were probably pension funds that wanted to increase their potential long-term returns by holding more equities but needed protection in case of a stock market meltdown.

In a filing, Berkshire Hathaway did not disclose any more detail about the contracts, including the premiums it would receive or the level the indices must fall below before it made a pay-out, the paper said.

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