Rubicon's IPO Filing: Who's Next?

The IPO filing by Rubicon Project is not only notable for one of Southern California's's fast growing Internet advertising companies: it looks to be the the first IPO filing by a venture-backed, technology startup since 2012. Although the region has had a number of IPOs in the last year, most of them have been on the biotechnology and medical devices side, with a notable drought in IPOs from the high technology side of the market here--a big contrast to the huge debuts in Silicon Valley of such firms as Twitter and Facebook last year. The question now: which other, big local technology startups are likely to follow Rubicon Project to market? Rumors around town over the last few years have included OpenX and SpaceX: there's also been speculation that whole home, wireless audio maker Sonos might be thinking about an IPO as well. However, local companies seem to have been pursuing a much easier route to liquidity lately -- one of the companies most talked about for an IPO in the last few years was LegalZoom, which ended up dropping its IPO bid in favor of a sale to private equity investor Permira.