While that number seems to be not a general value, the "Wegzugsbesteuerung" still is significant.

https://de.wikipedia.org/wiki/Wegzugsbesteuerung

Essentially, it assumes you sell your assets at market value and taxes the difference to your expenses for it.

That's what I was trying to say ("What is being taxed is the shares you're holding, as if you're selling them,") … did I word that poorly/confusingly?