The explosive growth of cell-phone subscriptions indicate that emerging markets could rebound in the coming years – giving investors a heads up of impending profits.

One of our most reliable indicators about emerging markets shows that investors may have a real slog ahead of them in the coming years. In the past, we’ve used cell-phone sales in growing economies as means of measuring the prospects for investments. Cell phones show how much disposable income is available, in addition to reflecting the entrepreneurial spirit that creates a healthy middle class.