The company filed to go public on the NYSE under the ticker symbol of ZSK on April 16, 2014. The expected offering amount was $100 million. Subsequently, the offering was withdrawn. Previously, the company raised $21 million in Series E venture funding from Keating Investments, Crosslink Capital and Canaan Partners on January 27, 2012, putting the pre-money valuation at $203.45 million. Bessemer Venture Partners and ATA Ventures also participated in this round.