(Bloomberg) -- An ETF that profits when interest rates rise has burned through more investor cash than any other in the industry.

The ProShares UltraShort 20+ Year Treasury fund has lost $6.1 billion of investor money since its inception in 2008, more than any other ETF has lost during its existence, according to data from Bloomberg Intelligence as of March 19.

The fund, which trades under the ticker TBT, is down 10.7% this year through Friday, losing 7.3% last week alone after the Federal Reserve sparked a rally in Treasuries by lowering its economic forecasts and the projected pace of rate hikes.

The fall in long-term U.S. government-bond yields has been damaging to a fund that profits when rates go the other way by betting against Treasury prices, which move inversely to yields, and magnifying those bets with borrowed money.

Wall Street has predicted rising interest rates for years, as the Fed moves closer to lifting the short-term policy rate it dropped to zero in December 2008 to combat the worst financial crisis since the Great Depression. Instead, Treasury prices have gained, driven by global central banks moving to ease monetary policy and assurances from the Fed that it won’t raise rates quickly.

“Rates never rose. The Fed has wreaked havoc on this fund,” said Eric Balchunas, an analyst with Bloomberg Intelligence.

“During its life -- a vigorous, extended bull market for bonds -- the fund delivered the performance its shareholders should have received based on its investment objective,” ProShares said in an e-mailed statement.

TIMING OFF

As of July 2014, ETF investors betting on higher volatility and a U.S. stock-market decline had lost the most long-term cash, as the iPath S&P 500 VIX Short-Term Futures ETN and the ProShares UltraShort S&P 500 ETF led the list of losers, according to Bloomberg Intelligence.

That changed late last year, after the CBOE’s Volatility Index had made a handful of jumps above its long-term average of 20. U.S. stocks have also slowed their ascent, with the S&P 500 up just 2.4% this year through Friday.

Many ETF investors don’t focus mainly on government bonds, seeking out returns in other places like global stock markets, and often use funds like TBT to limit the risk of losses from rising rates, Balchunas said.

Bryan Novak, managing director for Astor Investment Management in Chicago, said his firm has been trying to minimize potential interest-rate losses by buying the ProShares Short 20+ Year Treasury Fund.

That ETF, which trades under the ticker TBF, also profits from declines in long-term Treasury bond prices, but doesn’t use leverage like TBT.

“If you’re looking for a short-term trade, your timing is off,” he said. “But ultimately, the move higher in rates is going to happen.”

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