# Why does graphic of log first difference of renminbi look similar to hkd?

This is CNY to US$: This is HKD to US$:

Below are the log of the first difference of both graphs above:

You can see that apparent similarity on the middle of graph. I thought that they were managed by different entity as CNY are managed by People Bank of China (PBC, Central Bank of China) and HKD by Hongkong Monetary Authority CNY exchange rate is a managed float while HKD is pegged.

Questions:

1. Were the similarity induced by the same response to the same crisis? Or is it only coincidence? Or was it coordinated between financial authority in China and Hongkong? Or the way of how HK pegged HKD similar to the way how China managed float on CNY?
2. What are the implication of it?
-
Incorrect, a) returns in USDCNY are on average much more volatile than returns in USDHKD as you can see from your own charts, b) you can also see that USDCNY reflects more negative than positive returns while that is not the case for USDHKD. – Matt Wolf Nov 5 '13 at 4:56
you're right, but what about the middle part of the chart when it looks like the volatility are being suppressed? – Firhat Nawfan H. Nov 5 '13 at 12:19
Most likely it is related to low dollar volatility during that time period which impacted both USDCNY and USDHKD rates. – Matt Wolf Nov 5 '13 at 13:54