The New York-based hedge fund, which manages about $400 million, has added "a lot more" cheap, out-of-the-money options, betting the market is underestimating the likelihood of a crash, founder Russell Abrams said in a phone interview. Treasuries, German government bonds and Japan's yen are pricing in economic outcomes that are bleaker than the stock market expects, said the former co-head of U.S. equity derivative trading and convertible arbitrage at Merrill Lynch & Co.

"They are pointing to a much more dangerous environment than what equity investors believe," he said in an interview Aug. 27. "Either you're going to see the bond market make the the big move or the equity market make the big move; the current situation is not in equilibrium."

Nassim Nicholas Taleb, whose book "The Black Swan" is about how unforeseen events can roil markets, said Aug. 11 he is "betting on the collapse of government bonds" and that investors should avoid stocks. Government bonds around the world have rallied on growing signs the global economic recovery is faltering, driving yields on two-year Treasury notes as well as German 30-year and 10-year bonds to record lows last week.