Banks have increasingly been turning to the private, structured note market in the past few months to sell bonds that offer credit investors some protection from losses should the issuing firm’s creditworthiness start to deteriorate, according to new research.

In the first quarter of the year, US and European banks sold some $3.4bn (€2.1bn) equivalent of so-called puttable notes, or bonds, compared to sales worth $2bn throughout the whole of last year, according to specialist data provider mtn-i.