Really? I was under the impression that closing below your IPO price is quite rare indeed. Do you have other data?
Edit: actually, just saw a NYTimes article with info that it is indeed rare:
Since 2000, only 18 companies valued at more than $1 billion and listing on American exchanges have opened below their I.P.O. price. On average, tech stocks have jumped — or “popped,” in Wall Street parlance — 21 percent on their first day of trading over the past 24 years, according to Dealogic.
2008 has 31 Total IPO’s, restrict that to 1+ billion and you are not talking about a huge list. Restrict that to an unusual few years and it’s easy for an abnormal but meaningless pattern to show up. But, we have no need to make such assumptions.
PS: Facebook is something of an oddity, opening day has technical issues which ended up inflating the price.