Complex sentence: In May 2012, Shutterstock filed for an initial public offering on the New York Stock Exchange, which it completed on October 17th, 2012 under the ticker SSTK.
Split into simpler sentences: In May 2012, Shutterstock filed for an initial public offering on the New York Stock Exchange. On October 17,2012, Shutterstock completed its initial public offering on the New York Stock Exchange, trading under the ticker SSTK.