For investment-grade companies on the cusp of junk, borrowing might not be so bad on the other side.

The additional cost for firms to borrow in the U.S. high-yield market versus high-grade narrowed to 197 basis points Monday, the tightest since before the global financial crisis, according to Bloomberg Barclays index data. The spread last dipped below 200 basis points (bps) in 2007, the data show.

A relentless rally in junk-rated debt is narrowing the gap, as high-yield spreads also hit a pre-crisis tight Monday. Yields dropped to an all-time low as investors pile into riskier assets for higher returns, betting a recovery will boost particularly the most speculative names.