It does look like the IPO market is staging a comeback. But there are still perils.

Just take a look at Sourcefire Inc. (NASDAQ: FIRE). The company went public in mid March at $15 and quickly moved to a high of $18.83.

Well, investors got a rude shock yesterday as the shares plunged 29% to $12.28.

Basically, the company violated a cardinal rule in IPOs: it will miss its first quarterly numbers as a public company. In fact, the company expects to post a loss of $2.2 million to $2.6 million for the fiscal fourth quarter.

Sourcefire is a cutting-edge security company that sells to big-time clients. What's more, the company has a very popular open source version of its technology. All in all, it's a good IPO candidate -- but apparently management is not doing a good job in dealing with Street expectations.

I had a chance to talk to Nick Selby, who is the senior analyst of enterprise security at the 451 Group. According to him:

"Sourcefire has profited mightily by deftly walking a marketing line that has got investors thinking it's both a security company and an open source company. We argue that this 'open source premium' has contributed to the company's successful IPO: investors think security equals growth and open source equals cost savings.

"Sourcefire has a lot going for it, but it does have to meet its targets. Although, in the past it has met privately stated goals and its unofficial ballpark numbers."

Tom Taulli is the author of various books, including the Complete M&A Handbook and the EDGAR-Online Guide to Decoding Financial Statements.