Singapore is one of the world's few sovereign states with a triple-A credit rating on its debt, but its sliding currency is causing the country's government bonds to behave more like those from riskier emerging markets.
The Singdollar has fallen 7 per cent against its United States counterpart this year, depressed by a year-long monetary easing policy that has hurt demand for government bonds.
Investors are also shying away from Singapore assets as they seek higher returns in the US in the run-up to an expected rise in Federal Reserve interest rates.
While Singapore is Asia's only country with a Triple-A or top rating from all the three major ratings agencies, and is in the same league as Australia, Norway, Switzerland, Germany and Canada, local bond yields have spiked.
Over the past year, Singapore bonds have traded at yields much higher than the world's most liquid safe haven - US Treasury securities - while other top-rated markets have seen their yields decline relative to Treasuries.
"A depreciating currency and general emerging market fear could possibly deter investors from dealing with Singapore bonds," said Mr Gordon Ip, a senior fund manager at Value Partners in Hong Kong.
Singapore government bonds have not seen as much demand as most other safe-haven bonds, with the yield spread between 10-year Singapore bonds and Treasuries reaching 73 basis points in September. That was the widest since data was available going back to October 1998.
The benchmark 10-year Singapore bond yield is trading about 30 points above 10-year US Treasuries, compared with four points below Treasuries about a year earlier. In contrast, yields on German 10-year bunds trade 170 points below Treasuries now. Canadian bonds trade 60 points below Treasuries.
"The underperformance of Singapore bonds is a result of expectations of a stronger US dollar and somewhat heightened sensitivity of local interest rates to US rates," said Mr Mirza Baig, head of currency and rates strategy at BNP Paribas in Singapore.
The Monetary Authority of Singapore eased monetary policy via the Singdollar exchange rate mechanism twice this year to support the export-dependent economy against the backdrop of a global trade slowdown and heavy deflationary pressures. The Singdollar is Asia's fourth-worst performer this year.
Policy easing - via the Sing- dollar's nominal effective exchange rate against that of its main trading partners - has the side effect of pushing up money market rates and yields.
The three-month Singapore money market rate is now at 1.07 per cent and has climbed 62 points this year.