'Lost Decade'

As recently as April, Pimco's Worah wrote that inflation, not deflation, was the primary long-term concern in the U.S., given that the federal government could choose to address widening budget deficits by devaluing the dollar. Scott Mather, Pimco's head of global portfolio management, wrote in August that the odds had increased of the U.S. suffering a Japanese- style "lost decade."

"If you have inflation going down toward zero, you enter a new regime where expectations can become a self-fulfilling prophecy," Mather said in an interview. "That is what we saw in Japan as well," he said, referring to an era of declining real estate and equity prices that began in the early 1990s.

While the derivative contracts suggest that deflation fears have increased, the risk of deflation in the U.S. is lower than it was in Japan because the two countries have different currency policies, said Donald Ratajczak, an economic consultant and former director of the Economic Forecasting Center at Georgia State University.

'Bad Bet'

Japanese deflation stems from government policies to maintain the value of the yen that depleted the money supply there, said Ratajczak, who won acclaim from the Boston Federal Reserve Bank for his inflation forecast in the 1990s.

"We don't care as much about our dollar," said Ratajczak. "People who are betting on ten years of deflation are making a bad bet."

Wall Street dealers write derivative contracts for clients that want to bet on or protect their holdings from changes in interest rates, commodities, stock prices and other financial markets. The dealers can then keep the contracts, sell some of them to other Wall Street firms through the inter-dealer market, or find counterparties such as Pimco that will take the other side of the trade.

The value of inflation floors traded between dealers doubled to $3 billion in the first half of this year, from $1.5 billion for all of 2009, according to Miell at BGC Partners. That's a fraction of the $21.5 billion Fairfax Financial bought.

Buffett's Model