Foreign exchange rate risk arises from the movement of currency exchange rates over a period of time, leading to an adverse impact on the Group's earnings or shareholders' equity. The Group is exposed to foreign exchange rate risk in that the value of a financial instrument, or its net investment in its foreign subsidiaries, may fluctuate due to changes in foreign exchange rates. The Group's significant net foreign currency exposures as at 31 December 2017 are detailed in Note 28 to the Financial Statements.