Overreaction/ Asymetric mean-variance

Good afternoon people,

I am currently working on my thesis subject and want to prove overreaction of the main european indexes (FTSE, CAC, DAX) to the Greek debt crisis of 2015.
In order to do so, I need to find a model that allows the conditional mean and variance of returns to vary asymmetrically in response to previous up or down movements of all sizes.
Are some of the members aware of such model and how I could evaluate it on Eviews ?

Thank you.

Best,

Antoine B

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