"Academics have found that I.P.O. underpricing is ubiquitous. Jay Ritter has documented underpricing over the years. According to Professor Ritter, the average underpricing for I.P.O.’s in the United States was 14.8 percent from 1990 to 1998, 51.4 percent from 1999 to 2000 and 12.1percent from 2001 to 2009."

"Over the last 50 years, I.P.O.’s in the United States have been underpriced by 16.8 percent on average. This translates to more than $125 billion that companies have left on the table in the last 20 years."

Normal over the last 50 years, maybe.

http://dealbook.nytimes.com/2011/05/27/why-i-p-o-s-get-under...

It absolutely it not normal. If there was ALWAYS a 15% pop, then IPO prices would be 15% higher.

It's not a given that a stock that just popped 15% trades the same as a stock that was offered at a 15% higher price in the first place.

No, because you absolutely want that pop, so you get positive press. The last thing you want is an IPO where the price goes down