Imperva ( IMPV) took off as soon as it was public. The data security company priced its offering of 5 million shares on Nov. 8 at $18 each, raising $90 million. The stock opened on its first day of trading at $23, and closed Thursday at $34.12. Investors are taking a bit of a chance on Imperva because the company has never been profitable but the buzz on the stock is based on its rising topline growth as revenue jumped more than 40% year-over-year in the first nine months of 2011. Timing was also on Imperva's side as the company's IPO followed closely behind Groupon, and the company has won awards for its products that protect high-value data from hackers.