The suit filed by two pension funds -- the Middlesex County Retirement System in Massachusetts and the pension fund of the Steamship Trade Association-International Longshoreman's Association (STA-ILA) -- alleged Monster backdated stock options that were handed out to employees.

Judge Jed Rakoff of U.S. District Court for the Southern District of New York ruled on Monday the proposed class consists of thousands of potential members and that many lacked the resources to litigate their claims against the defendants individually. The judge found "the class action is the superior method of adjudication."

Monster spokesman Steve Sylven said the company does not comment on pending litigation.

The Middlesex group was approved to represent the class, although the STA-ILA was not.

The lawsuit named as defendants former Chief Executive Andrew McKelvey, as well as the former general counsel, senior vice president and Secretary Myron Olesnyckyj.

The suit contended, among other complaints, that McKelvey engaged in a system of backdating option grants to ensure they were deeply "in-the-money" when they were granted -- making them more valuable to recipients.

Monster shares rose 6 percent to $18.31 in a broadly higher market and has traded in a 52-week range of $17.25 to $42.34.

(Reporting by Chelsea Emery; additional reporting by Nick Zieminski in New York; editing by Jeffrey Benkoe and Andre Grenon)