Why is it important to be aware of the currency of issue? Four reasons:
1. Currency risk
A bond that isn’t denominated in your own currency effectively has unknown future cashflows because you do not know what it is going to be worth in terms of your own currency in the future.
Of course, if you buy a bond denominated in a foreign currency this is a currency play in itself; you wouldn't buy a bond denominated in a currency you thought was going to fall in value against your reference currency.
But just because you think the currency the bond is denominated in is going to either hold its value or rise in value relative to your reference currency, it doesn't mean it is. There is a risk that it won't. There is currency risk.
To take a simple example, imagine buying a Swiss franc denominated eurobond when your reference currency is US dollars. Where the bond's coupon payments and repayment of principal are fixed both the interest earned on the bond and the principal at maturity could be worth less than you expect if the Swiss franc falls in value against the dollar.
Of course, if the Swiss franc rises in value against the US dollar both the coupon payments and the principal would be worth more in terms of your reference currency.
The lesson is: if you buy a bond denominated in a foreign currency you are taking on currency risk.
2. Country risk
This is the risk that the country where the bond is issued is fundamentally unstable and that this is going to impact on the bond’s issuer to the extent that they cannot meet their obligations – in terms of interest payment and the repayment of principle. To the extent that the rating agencies take account of country risk, an issuer’s credit rating should tell you all you need to know.
3. Taxation
Are you going to be liable for any additional taxes (or any tax breaks) by virtue of holding a non-domestic bond.
4. Regulation
Are you happy about the regulatory environment – or lack of a regulatory environment - the bond was issued in and is governed by.