Sovereign Risky Business

Looks like Australia's Sovereign risk is back to it's long term average after a few years of surging. Hopefully this bodes well for future investment. The formula I am using is Sovereign risk = (Spread between 10 year Australia government bond and US 10 year Government bond)* STDEV(ASX200 returns)/STDEV(Australia 10 year bond yields). Get the following graph for the last 10 years