Exxon Mobil Corp.(XOM) (22%)
ConocoPhillips(COP) (4.2%)
Kinder Morgan Inc./DE(KMI) (3.9%)
Williams Cos. Inc.(WMB) (3.8%)
EOG Resources Inc.(EOG) (3.2%)
Schlumberger Ltd.(SLB) (3.2%)
Marathon Petroleum Corp.(MPC) (3.1%)
Valero Energy Corp.(VLO) (2.6%)