Wikipedia offers this:
http://en.wikipedia.org/wiki/Initial_public_offering
"The underpricing of initial public offerings (IPO) has been well documented in different markets (Ibbotson, 1975; Ritter 1984; Levis, 1990; McGuinness, 1992). While Issuers always try to maximize their issue proceeds, the underpricing of IPOs has constituted a serious anomaly in the literature of financial economics. Many financial economists have developed different models to explain the underpricing of IPOs. Some of the models explained it as a consequences of deliberate underpricing by issuers or their agents. In general, smaller issues are observed to be underpriced more than large issues (Ritter, 1984, Ritter, 1991, Levis, 1990) Historically, IPOs both globally and in the United States have been underpriced. The effect of "initial underpricing" an IPO is to generate additional interest in the stock when it first becomes publicly traded. Through flipping, this can lead to significant gains for investors who have been allocated shares of the IPO at the offering price. However, underpricing an IPO results in "money left on the table"—lost capital that could have been raised for the company had the stock been offered at a higher price. One great example of all these factors at play was seen with theglobe.com IPO which helped fuel the IPO mania of the late 90's internet era. Underwritten by Bear Stearns on November 13, 1998 the stock had been priced at $9 per share, and famously jumped 1000% at the opening of trading all the way up to $97, before deflating and closing at $63 after large sell offs from institutions flipping the stock . Although the company did raise about $30 million from the offering it is estimated that with the level of demand for the offering and the volume of trading that took place the company might have left upwards of $200 million on the table."
All the same, Wikipedia also offers a charitable explanation for the phenomena:
"The danger of overpricing is also an important consideration. If a stock is offered to the public at a higher price than the market will pay, the underwriters may have trouble meeting their commitments to sell shares. Even if they sell all of the issued shares, if the stock falls in value on the first day of trading, it may lose its marketability and hence even more of its value."
A small amount of "Pop" (no more than 10 percent) isn't a bad thing. It is a result of oversubscription, which every underwriter needs in order to assure they aren't left holding the bag. It also makes stabilization (the only legal form of market manipulation) less expensive for the underwriter.
You're going to see more extreme cases of "pop" in a market with a lot of uncertainty (like we have now). This is the underwriter being cautious. Their worst case scenario doesn't appear and the IPO turns out to be underpriced.
What we saw in the late 1990's was heinous. I worked at a startup investment bank (Epoch Partners) that was intended to take some of the pop out of IPOs (and make allocation more available to genuine retail investors).
-r
Why rely on guess work?
Edit: I saw on the linked Wikipedia article that some people have tried auctions. Google seemed a noteworthy example.