The rest of the decline reflects a slowdown in trend productivity growth, which is common to many advanced economies. This slowdown in potential growth has probably translated about one-for-one into a decline in the neutral rate, though the decline has been gradual.
Kevin M Warsh: Remarks on covered bond framework Speech by Mr Kevin M Warsh, Member of the Board of Governors of the US Federal Reserve System, at the US Department of the Treasury Press Conference on Covered Bond Framework, Washington DC, 28 July 2008.