Sam and Charles Wyly, of Dallas, made more than $550 million in undisclosed profits through 13 years of insider trading, according to a complaint filed in New York by the SEC this week. The SEC alleged that the brothers used an elaborate network of offshore entities to conceal their buying and selling of shares in companies on whose boards they served. If the SEC proves its allegations, the case would rank as one of the biggest insider-trading scandals in history. The Los Angeles Times says Sam Wyly, a member of the Forbes 400 list of richest Americans, and his brother are known for their support of conservative candidates and causes — both Presidents Bush received campaign donations. Sam Wyly”s net worth was estimated at $950 million in the latest Forbes rankings. The SEC’s suit also listed as defendants the brothers’ attorney, Michael C. French, and their broker, Louis J. Schaufele III.