Trustwave Holdings, provider of security and compliance solutions, on Thursday announced plans to file for an initial public offering to raise up to $100 million in stock. The number of shares being offered and their expected price have not been determined, according to a news release. According to reports, the Chicago-based company has posted losses in each of the last three years but has seen revenue rise during that time. An IT security IPO is rare. Fortinet in 2009 and ArcSight in 2008 were two of the most recent security firms to file for public status.