Hi, I have a little knowledge of financial time series. However, I think you can consider Value -at-Risk (VaR) and GARCH Models in this regard.

 Dear  Madam

Thank you so much for your consideration. In my previous paper, I have used GARCH and VAR  Modeling. Besides this, please inform me if possible.

Best Regards,

Ahammad Hossain 

Can you read Chinese? I have an article gives a method, perhaps you can read it.

The easiest to do is to calculate the standard deviation and use it as a measure of  financial risk. 

Thank you Zheng Wang and  Krishna Swamy

Dear Ahammad Hossain 

Greetings,

Please find the attached file may be good for you and related for your topic.

time series:

Best Regards,