For big deals that take one or two years to finish, the acquirer usually has financial arrangements to hedge the risks of exchange rate fluctuations, according to Rosa Yang, chairman of Deloitte's Global Chinese Services Group.

China's central bank, the People's Bank of China, cut the yuan's reference rate against the US dollar to 6.2298 on Aug 11, to align the Chinese currency with current market forces.

For Simon Harris, managing director for global insurance and managed investments with the ratings agency Moody's, a low interest rate environment and regulatory changes in the US and EU provide rare M&As.