Ten-year U.S. Treasury yields have surged over 39%, but a different tune has been sung over the past few days. Yields on ten-years have slid 8.2% as investors see a more sanguine outlook for bonds, predictably benefiting some of the largest bond ETFs in the process.

The iShares 20+ Year Treasury Bond ETF (NYSEArca: TLT) and the iShares iBoxx $ Investment Grade Corporate Bond ETF (NYSEArca: LQD) are among the large bond ETFs that have recently made important technical breakouts, indicating more upside could be on the way, as technical analyst Chris Kimble notes.

With 10- and 30-year yields being rebuffed at important resistance points, the iShares Core Total U.S. Bond Market ETF (NYSEArca: AGG) and the SPDR Barclays High Yield Bond ETF (NYSEArca: JNK), the second-largest junk bond ETF by assets, have also made notable advances over the past few days. [Bond ETFs in a Post-Default World]

Performances for that quartet over the past five days have been strong as TLT is up 3.4% and AGG is higher by 1.11%. JNK is higher by 1.2%, but the market has favored high-grade corporates as LQD is up almost 2%. [Another Look at Junk Bond ETFs]