Seven of the 30 largest U.S. corporations paid more money to their chief executive officers last year than they paid in U.S. federal income taxes, according to a study released on Tuesday that was disputed by at least one of the companies. Amid talk in Washington about corporate tax reform, the study said the seven companies, which in 2013 reported more than $74 billion in combined U.S. pre-tax profits, came out ahead on their taxes, gaining $1.9 billion more than they owed.