The current situation: Endless liability
The Supreme Court passed a verdict in 2012, declaring that information requirements related to the stock exchange law, especially the requirement to make ad-hoc announcements (§ 48 (d) of the Stock Exchange Act) and the prohibition on market manipulation (§ 48a (1) (2) (c) of the Stock Exchange Act) are protective laws and breaching them can lead to an issuer becoming liable for damages. By doing so, the court set the bar for liability especially low. A Supreme Court decision of 20/03/2015 now places the burden of proof on the investor. The investor must prove that they were actually aware of an ad-hoc announcement (or were aware that it did not take place) and that they would have then changed their investment accordingly.
Full article in German