The relationship between the Japanese Yen and the spread between the US 30-year treasury yield and US 10-year yield has had a very tight negative correlation (-0.85) over the past 10-years (since 1986 when the bond spread series begins the correlation is -0.61). Since the end of March, the 30/10 spread has widened by 18 basis points to its widest levels in about 7 months. The Yen, meanwhile, is basically unchanged against the USD in the past two months. In 2012 after a divergence opened up, the yen began a multi-year period of weakness as it moved from 78 to 120. It will be worth watching if the divergence this time sparks a rally in the yen or if the long end of the yield curve is about to flatten out once again.