The emerging-market average yield shrank to the lowest levels all time on Thursday as the Bank of Japan decided to double its monetary base in next two years in order to fight deflation in the country boosting demand for higher-yielding assets. The average yield in emerging markets tracked by JPMorgan Chase & Co. dropped 0.16% since April 3 with the South Africa's 10-year yield fell 0.12 percentage points to 6.52% this week.