Generally regarded by whom* exactly? The world is full of examples of IPOs that did badly on opening day/week but soared like mad afterwards. These generalizations and pretense of knowledge helps no one; especially considering that "over-valued" is not something that can be determined in a short period of time as value is relative to the context in which the asset presents itself.
* as a non-native English speaker, did I use whom correctly or should it be "who"?
Edit: thank you for the reply mr scarejunba!