Spreads on U.S. five-year credit default swaps widened to 62 basis points, data from S&P Global Market Intelligence showed, up from a close of 59 bps on Tuesday.

This is more than double the level they stood at at the start of the year and represents the highest level since 2011, according to Refinitiv data.

U.S. Treasury Secretary Janet Yellen on Tuesday warned that failure by Congress to raise the government’s debt ceiling - and the resulting default - would trigger an “economic catastrophe” that would send interest rates higher for years to come.