Investors, particularly hedge funds, have been exploring the "last frontiers", both by assets and geographically, in emerging markets that are too small or insufficiently liquid to be included in the main benchmark indices.

Vietnam - not included in the main emerging market benchmarks - is attracting interest. Foreign investors are estimated to have spent $123m (€93m, £63m) buying Vietnamese stocks over the past three months, and now own about 31 per cent of the market.