MR Montage Resources Corporation

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Explanatory Note

This Amendment No. 11 (this “Amendment”) amends the information provided in the Schedule 13D (the “Original Schedule 13D”) filed with the SEC by Eclipse Resources Holdings, L.P. (“Eclipse Holdings”), EnCap Energy Capital Fund VIII, L.P. (“EnCap Fund VIII”), EnCap Energy Capital Fund VIII Co-Investors, L.P. (“EnCap Fund VIII Co-Invest”), EnCap Energy Capital Fund IX, L.P. (“EnCap Fund IX”), David B. Miller, D. Martin Phillips, Gary R. Petersen and Robert L. Zorich on July 7, 2014, as amended by that certain Amendment No. 1 filed on January 13, 2015, that certain Amendment No. 2 filed on February 2, 2015, that certain Amendment No. 3 filed on July 15, 2016, that certain Amendment No. 4 filed on September 30, 2016, that certain Amendment No. 5 filed on January 18, 2018, that certain Amendment No. 6 filed on September 2, 2018, that certain Amendment No. 7 filed on February 6, 2019, that certain Amendment No. 8 filed on March 1, 2019, that certain Amendment No. 9 filed on October 30, 2019, and that certain Amendment No. 10 filed on August 12, 2020. This Amendment amends the Original Schedule 13D on behalf of the undersigned to furnish the information set forth herein and relates to the beneficial ownership of the shares of common stock, $0.01 par value per share (“Common Stock”), of Montage Resources Corporation (formerly known as Eclipse Resources Corporation), a Delaware corporation (the “Issuer”). Except as otherwise specified in this Amendment, all items left blank remain unchanged in all material respects and any items that are reported are deemed to amend and restate the corresponding items in the Original Schedule 13D in their entirety.

This Amendment is being filed on behalf of the reporting persons identified on the cover pages of this Amendment. Capitalized terms used in this Amendment and not otherwise defined shall have the same meanings ascribed to them in the Original Schedule 13D. This Amendment constitutes an exit filing for the Reporting Persons in respect of Common Stock previously reported as beneficially owned by the Reporting Persons.

Item 2 of the Original Schedule 13D is amended to include the following after the final paragraph:

As a result of the Merger, as discussed further below in Item 4, the separate existence of the Issuer has ceased and Southwestern is the surviving entity in the Merger.

Item 4 of the Original Schedule 13D is amended to include the following after the final paragraph:

Completion of Southwestern Merger

On November 13, 2020, the transactions contemplated by the Merger Agreement were consummated. Pursuant to the terms of the Merger Agreement, each issued and outstanding share of Common Stock was converted into the right to receive 1.8656 shares of common stock, $0.01 par value per share, of Southwestern. As a result of the Merger, the Support Agreement was terminated in accordance with the terms of the Support Agreement upon the Effective Time.

As a result of the foregoing and as of the Effective Time, EnCap Fund VIII, EnCap Fund VIII Co-Invest, EnCap Fund IX, TPR Residual Assets, LLC and EnCap Partners GP, LLC no longer beneficially own any shares of Common Stock.

Item 5 of the Original Schedule 13D is amended to include the following after the final paragraph:

The information set forth in Item 2 of this Amendment is incorporated by reference herein. As a result of the Merger, the Reporting Persons no longer own any shares of Common Stock. Consequently, this Amendment constitutes an exit filing for the Reporting Persons.

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Item 6 of the Original Schedule 13D is amended to include the following after the final paragraph:

The information set forth in Item 4 of this Amendment is incorporated by reference herein.

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: November 13, 2020

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