X0306 4 2017-11-01 0 0000086264 Carbon Energy Corp CRBO 0001667954 Yorktown Energy Partners XI, L.P. C/O YORKTOWN PARTNERS LLC 410 PARK AVENUE, 19TH FLOOR NEW YORK NY 10022 0 0 1 0 Common stock, par value $0.01 per share 2017-11-01 4 M 0 432051 A 432051 D Warrant 2017-11-01 4 M 0 432051 D 2017-04-03 2024-04-03 Common Stock, par value $0.01 per share 432051 0 D Shares received upon exercise of Warrant No. 2, issued on April 3, 2017 (the "CAC Warrant") to the reporting person. The consideration the reporting person paid for the full exercise of the CAC Warrant was the transfer and assignment to Carbon Natural Gas Company (the "Issuer") of 2,940 Class A Units of Carbon Appalachian Company, LLC, a Delaware limited liability company. These shares were inadvertently omitted from one Form 4 filed by the reporting person on April 9, 2018. Yorktown Energy Partners XI, L.P., By: Yorktown XI Company LP, its general partner, By: Yorktown XI Associates LLC, its general partner, /s/ Peter A. Leidel, Manager 2018-09-18