UNITED STATES NATURAL GAS FUND, LP AMENDMENT NO. 2 TO MARKETING AGENTAGREEMENT

Exhibit 10.3

UNITED STATES NATURAL GAS FUND, LP

AMENDMENT NO. 2 TO MARKETING AGENT AGREEMENT

This Amendment No. 2 dated July 30, 2012 to the Marketing Agent Agreement by and among United States Natural Gas Fund, LP, a Delaware limited partnership (the “Fund”), United States Commodity Funds LLC, formerly Victoria Bay Asset Management, LLC, a Delaware limited liability company, as General Partner of the Fund (the “General Partner”) and ALPS Distributors, Inc., a Colorado corporation (the “Marketing Agent”).

WITNESSETH

WHEREAS, the Fund, the General Partner and the Marketing Agent entered into a Marketing Agent Agreement dated as of April 17, 2008;

WHEREAS, the Marketing Agent Agreement was amended by the Fund, the General Partner and the Marketing Agent effective March 24, 2008 (collectively, the “Agreement”); and

WHEREAS, the Fund, the General Partner and the Marketing Agent wish to amend the Marketing Agent Agreement.

NOW, THEREFORE, in consideration of the mutual covenants and agreement herein contained, the Fund, General Partner and the Marketing Agent hereby agree as follows:

United States Commodity Funds LLC

1999 Harrison Street, Suite 1530

Oakland, California 94612

[SIGNATURES ON FOLLOWING PAGE]

IN WITNESS WHEREOF, each of the parties hereto has caused this Amendment No. 2 to be duly executed as of the date first written above.

UNITED STATES NATURAL GAS FUND, LP

By: United States Commodity Funds LLC, as General Partner

UNITED STATES COMMODITY FUNDS LLC

ALPS DISTRIBUTORS, INC.