NEW YORK, July 26 (Reuters) - U.S. credit default swap spreads widened dramatically on Thursday because of worries about a heavy forward calendar of debt supply and turmoil in the subprime mortgage market, market sources said.
The investment-grade index widened about 4.5 basis points to around 61.5 basis points, while an index of high-volatility credits widened about 9 basis points to 159 basis points.
