SECOND SUPPLEMENTAL INDENTURE

Exhibit 4.1

SECOND SUPPLEMENTAL INDENTURE

SECOND SUPPLEMENTAL INDENTURE dated as of August 31, 2009 (this “ Supplemental Indenture ”), among Comcast Corporation, a Pennsylvania corporation (the “ Company ”), Comcast Cable Holdings, LLC, a Delaware limited liability company, Comcast Cable Communications, LLC (f/k/a Comcast Cable Communications, Inc.), a Delaware limited liability company, Comcast MO Group, Inc., a Delaware corporation, Comcast MO of Delaware, LLC (f/k/a Comcast MO of Delaware, Inc.), a Delaware limited liability company (collectively the “ Guarantors ”), and The Bank of New York Mellon (f/k/a The Bank of New York), as trustee (the “ Trustee ”).

WHEREAS, the Company is the issuer under the Indenture, dated as of January 7, 2003, as supplemented by a First Supplemental Indenture, dated as of March 25, 2003 (collectively, the “ Original Indenture ” and together with this Supplemental Indenture, the “ Indenture ”), pursuant to which the Company issued, and the Trustee authenticated and delivered certain securities which are, as of the date hereof, outstanding (the “ Outstanding Securities ”) and pursuant to which the Company may issue securities in the future (the “ New Securities ,” and together with the Outstanding Securities, the “ Securities ”);

WHEREAS, the Guarantors identified above along with Comcast Cable Communications Holdings, Inc., a Delaware corporation (the “ Non-Surviving Guarantor ”), irrevocably, fully and unconditionally guaranteed, jointly and severally, on an unsecured basis, the full and punctual payment (whether at maturity, upon redemption, or otherwise) of the principal and interest on, and all other amounts payable under, each Security, and the full and punctual payment of all other amounts payable by the Company under the Original Indenture;

WHEREAS, as of the date hereof, the Non-Surviving Guarantor has merged with and into Comcast Cable, with Comcast Cable as the surviving entity;

WHEREAS, the Company and the Guarantors have requested that the Trustee execute and deliver this Supplemental Indenture to reflect the merger of the Non-Surviving Guarantor with and into Comcast Cable, and all requirements necessary to make this Supplemental Indenture a valid instrument in accordance with its terms, and the execution and delivery of this Supplemental Indenture have been duly authorized in all respects;

WHEREAS, pursuant to Section 7.01(g) of the Indenture, the Company and the Trustee, may, without consent of the Holders, when so authorized by the Board of Directors of the Company, enter into a supplement to the Indenture to make any change that does not adversely affect the rights of any Holder;

NOW, THEREFORE, the Company, the Guarantors and the Trustee do hereby supplement and amend the Original Indenture pursuant to Section 7.01 without notice to or consent of any Holder as follows:

ARTICLE 1

Definitions