Comcast Corp Chief Executive Officer Brian Roberts will pay a $500,000 civil penalty for failing to notify antitrust authorities before acquiring voting securities in the cable company as part of his compensation package, the U.S. Justice Department said on Friday.

Roberts violated the notification requirements of the Hart-Scott-Rodino Act, between Oct. 22, 2007 and April 2009 by receiving Comcast voting securities without filing notification to the U.S. Federal Trade Commission and Department of Justice, according to the complaint.

According to the complaint, Roberts failed to notify regulators before acquiring voting securities of Comcast as part of his compensation beginning in Oct. 2007. This resulted in his holding around $120 million of Comcast stock.

The HSR Act of 1976 requires that executives and companies over a certain size observe waiting periods and notify regulators before they buy stock or assets above a certain value, which was $59.8 million in 2007 and is currently $66 million.

Roberts' total compensation in 2010 was just over $31 million. He controls one-third of Comcast's voting stock and owns less than 2 percent of the company's equity, according to a company filing.

Comcast said in a statement on Friday that the issue was a "technical and inadvertent violation that was self-reported, promptly corrected, and did not involve any financial gain to the company or Mr Roberts."