X0304 5 2011-12-31 1 0 0 0000086264 Carbon Natural Gas Co CRBO 0001516491 RBCP Energy Fund Investments, LP, c/o RBC Capital Partners ROYAL BANK PLAZA, SOUTH TOWER, 5TH FLOOR 200 BAY STREET, PO BOX 50 TORONTO A6 M5J 2W7 ONTARIO, CANADA 0 0 0 1 Former 10% Owner Common Stock 8153777 D The reporting person ceased to be a 10% owner as a result of CRBO's issuance of shares of common stock in connection with a private placement that closed on June 29, 2011. Kevin D. Struzeski, by power of attorney 2012-02-07