A federal judge in a New York district court has certified two classes of plaintiffs in a claim alleging Facebook mislead investors prior to its 2012 initial public offering.

Earlier in December, U.S. district judge Robert Sweet named the North Carolina Retirement Systems, Arkansas Teacher Retirement System and the Fresno County Employees’ Retirement Association among the lead plaintiffs representing a class of institutional investors.

Read: Volkswagen sued by pension fund over emissions scandal

Facebook is reportedly appealing the certification of the classes in appellate court.

In certifying two classes of plaintiffs, Judge Sweet is combining some 40 claims that Facebook withheld inside company information about how increased mobile usage would affect future revenues.

Read: State pension funding levels improved except in these states

In an earlier document addressing claims by some of the pension funds, Sweet wrote that “the company's purported risk warnings misleadingly represented that this revenue cut was merely possible when, in fact, it had already materialized," according to reporting in Reuters.

Shares of Facebook’s $16 billion IPO were priced at $38. They fell to about $17.50 four months later, in September 2012, in part on fears that the company was struggling to monetize its mobile platform. The stock stayed below the price of the IPO for about a year.

The public pensions involved claim to have lost about $7 million from IPO investments.

Facebook representatives maintain that claims the company withheld information from institutional and retail investors are without merit.