US authorities said Friday that Comcast chief executive Brian Roberts would pay $500,000 to settle charges that he violated stock buying rules. The Justice Department said Roberts will pay the civil penalty "to settle charges that he violated pre-merger reporting and waiting requirements when he acquired Comcast voting securities." The department filed the antitrust lawsuit in the US federal court in Washington, and separately proposed the settlement, which requires court approval. Roberts also is chairman of the board of Comcast, the largest cable television operator and high-speed Internet provider in the United States. Roberts twice before had "made corrective filings" after failing to file and observe the waiting period, but this was the first time he was charged with an antitrust violation, the Justice Department said in a statement. In a statement Comcast said the failure to file was "technical and inadvertent" and "did not involve any financial gain to the company or to Mr. Roberts." A Comcast spokesperson said lawyers had put in place safeguards to ensure it would not happen again.