I came across this story which I need to read more, but it's an interesting analysis that US banks have a favourable accounting treatment which may attract change. http://www.bloomberg.com/news/2013-02-20/u-s-banks-bigger-than-gdp-as-accounting-rift-masks-risk.html I posted too soon, ISDA have already followed up on the story here: http://isda.mediacomment.org/2013/02/25/the-net-net-on-netting-and-risk/