Initial public offerings have been making headlines recently when new Internet-related stocks have doubled or even tripled on their first day of trading. This week, the headline is more about volume: According to Renaissance Capital, 12 U.S. companies are slated to go public, potentially marking the biggest week for IPOs in about four years.

So far this year, there have been 84 IPOs, up 18 per cent from the same period last year and highlighted by the likes of LinkedIn Corp. (LNKD-N104.850.800.77%) and Zillow Inc. (Z-Q28.43-1.79-5.92%), whose share prices zoomed from the opening trade. While heating up, IPO activity is still muted compared to some years. In 1999, for example, there were 486 IPOs, while activity averaged about 200 per year from 2004 to 2007, before the financial crisis in 2008 dried things up.

Overall, though, IPOs continue to deliver poor results for investors – an underperformance that has been supported by academic evidence. Renaissance Capital noted that the FTSE Renaissance IPO index has fallen 0.4 per cent this year, against a gain of 6.9 per cent for the S&P 500, as of Friday.

This week’s roster of IPO candidates lacks the star power of an social-networking stock, but it does come with donuts: Dunkin’ Brands Group Inc. is seeking to raise $400-million (U.S.) through a listing on Nasdaq.