Investors representing some £3.4 trillion of assets have voiced concerns that their fears over the loosening of covenants in the European high yield debt market continue to go unheeded, as research indicates investor protection could be slipping further.

Eight months ago, in an open letter to the region's banking trade body, the Association for Financial Markets in Europe, a group of 22 investors complained about a lack of investor protection in the terms of high yield bonds. Now a similar-sized survey of investors has found that not one has seen an improvement.