[arcturus17]

It is my understanding that the stock price of IPOs is often inflated through different mechanisms - maybe another commenter who knows more than I do can explain what these are.

At any rate, if they really released at pricing levels determined by transparent and efficient markets we wouldn't see these pops, would we?

[fractionalhare]

You could actually say IPO pops (and drops) are a temporarily more extreme price discovery process when a company transitions from relatively inefficiently traded private entity to a more efficiently traded public one.