Investors had a tough second quarter as the S&P 500 closed June up a mere 1.8% for the year. Unlike prior periods, where the IPO calendar slows dramatically in dicey markets, we have actually seen a pickup in IPO activity in recent weeks. Why the sudden interest?

With the average stock not doing much of anything, investors seem to be looking anywhere for places to make money. New offerings, whether well-known consumer brands like J Crew or Mastercard, or much hyped ethanol plays like VeraSun and Aventine, offer the potential for a quick payoff, something that has been lacking for several months in the market.

The retail investor seems to be jumping in with both feet to the IPO market, which I would use as an indication that it's time to tread carefully. Despite lackluster financials, small investors jumped all over the J Crew deal, causing a huge spike. On a valuation basis though, the stock does not appear cheap. The ethanol plays are also expensive, with the Aventine deal actually dropping more than 10% on its first day of trading last week.

History has shown that IPOs are some of the worst investments around. Just think about why this is likely the case. Companies don't sell shares to the public unless they think they can get a great price. Why are ethanol companies going public now, even though oil prices have been high for a fairly long time? Perhaps they are sensing that speculative interest in the industry is at elevated levels and they want to take advantage of that.

The fact that many deals, including J Crew, are being brought to market by private equity firms is another red flag. These buyout firms bought companies years ago when prices were depressed. Now the so-called "smart money" is selling their stakes to the retail investor via IPOs. Which side of that trade do you think is going to come out on top?

Of course there will be exceptions, but I would caution investors to be careful when venturing into the IPO market. There is a reason why someone has decided this is the right time to sell. With initial public offerings having been relatively poor investments over time, make sure you pay attention to the stock's valuation, not just what company you are dealing with.