A study investigates auditor concentration in the energy industry in the Big Four era, a period also marked by enactment of the Sarbanes-Oxley Act of 2002 (SOX) which some have claimed has further reduced client choice. Also, the "subprime" crisis of 2008 has triggered fears that litigation arising from bankruptcies in the financial sector may cause a further decrease in the number of "Big" firms. Contrary to expectations, auditor concentration in the energy sector has been steadily decreasing since 2002. This finding was independent of the concentration metric employed. Among the Big Four firms, the Herfindahl Indices also indicated increased competition. Trends toward decreased auditor concentration were similar for NYSE listed energy firms and for those listed on other exchange. By most measures, the market for audit services in the energy industry is highly concentrated. Yet the trend is unmistakably toward an energy sector less dominated by the Big Four - and toward a market where the Big Four are more competitive with each other.