U.S. home-loan bonds without government backing tumbled last month leaving several types of debt trading at their lowest prices of the year, Bloomberg writes.

Declines reached almost 22% in June among certain subprime-mortgage securities, according to a June 28 report by Bank of America (BAC).

While returns remain positive this year among subprime-backed bonds, including gains of 12.5% for those notes, losses in 2013 for other non-agency securities are as high as 4% and bonds tied to mortgages known as prime-jumbo and Alt-A loans now trade below values at the end of last year, according to the report and data from Barclays Plc (BCS).