Some of the tech companies that have gone public this year:
Demand Media Inc., online content publisher, Jan. 26
Zipcar Inc., online car rental company, April 14
LinkedIn Corp., online professional network, May 19
Pandora Media Inc., Internet radio company, June 15
Zillow Inc., real estate website, July 20
Groupon Inc., online deals company, Nov. 4
Angie’s List Inc., consumer-reviews site, Nov. 17.