Facebook is appealing the class certifications, which the Menlo Park, California-based company said are 'without merit' and conflict with 'well-settled' precedent A federal judge has certified two shareholder class actions accusing Facebook Inc of hiding concerns about its growth forecasts prior to the social media company's May 2012 initial public offering. US District Judge Robert Sweet in Manhattan said retail and institutional investors who claimed to lose money from buying Facebook shares at inflated prices in connection with the $16 billion IPO may pursue their respective claims as groups. The decision is dated December 11 but had been kept under seal, which Sweet lifted in an order made public on Tuesday. Other Facebook defendants include chief executive Mark Zuckerberg, chief operating officer Sheryl Sandberg and other officials. Facebook is appealing the class certifications, which the Menlo Park, California-based company said are "without merit" and conflict with "well-settled" precedent.