Oct. 2 (Bloomberg) -- Yields over benchmark rates on U.S. speculative-grade bonds widened to a record 12 percentage points, Merrill Lynch & Co. data show.

The gap between high-yield bonds and similar-maturity Treasuries jumped 76 basis points today to 1,200 basis points, the highest since Merrill began compiling spread data for its U.S. High-Yield Master II Index in December 1996.

The increase was the biggest since Sept. 14, 2001, the first day financial markets opened after terrorist attacks on New York and Washington, when spreads widened 119 basis points.

The previous high spread was 1,120 basis points, set on Oct. 10, 2002. A basis point is 0.01 percentage point.

Investment-grade spreads widened 26 basis points to a record 487 basis points, according to Merrill's U.S. Corporate Master Index.

To contact the reporter on this story: Bryan Keogh in New York at bkeogh4@bloomberg.net

Last Updated: October 2, 2008 18:20 EDT