The TED spread, the difference between what lenders and the U.S. government pay to borrow for three months, widened to 47 basis points today, or 0.47 percentage point, the most since June 2010.
Yields have yet to reach the levels seen three years ago when credit markets froze and the U.S. economy was in a recession. The TED spread was as wide as 4.64 percentage points in October 2008.
While U.S. banks have hedged some of their risk with credit-default swaps, those may not be effective if voluntary debt forgiveness becomes "more prevalent" and the insurance provisions of the instruments aren't triggered, Fitch said in the report. The top five U.S. banks had $22 billion in hedges tied to stressed markets, according to Fitch.
Disclosure practices also make it difficult to gauge U.S. banks' risk, Fitch said. Firms including Goldman Sachs and JPMorgan don't provide a full picture of potential losses and gains in the event of a European default, giving only net numbers or excluding some derivatives altogether.
Guarantees provided by U.S. lenders on government, bank and corporate debt in Greece, Italy, Ireland, Portugal and Spain rose by $80.7 billion to $518 billion in the first half of 2011, according to the Bank for International Settlements.
Also yesterday, Moody's Investors Service downgraded the senior debt and deposit ratings of 10 German public-sector banks, citing its assumption that "there is now a lower likelihood" that the lenders would get external support.