Sec Form 4 Filing - EnCap Energy Capital Fund VIII, L.P. @ Montage Resources Corp - 2020-11-13

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person EnCap Energy Capital Fund VIII, L.P. 2. Issuer Name and Ticker or Trading Symbol Montage Resources Corp [ MR] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 1100 LOUISIANA STREET, SUITE 4900 3. Date of Earliest Transaction (MM/DD/YY) 11/13/2020 (Street) HOUSTON, TX77002 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 11/13/2020 D( 1 ) 2,694,673 D 0 ( 3 ) I See footnote ( 4 ) ( 5 ) Common Stock 11/13/2020 D( 1 ) 4,856,485 D 0 ( 3 ) I See footnote ( 6 ) Common Stock 11/13/2020 D( 1 ) 3,979,173 D 0 ( 3 ) I See footnote ( 7 ) Common Stock 11/13/2020 D( 1 ) 2,521,573 D 0 ( 3 ) I See footnote ( 8 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other EnCap Energy Capital Fund VIII, L.P. 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX77002 X EnCap Energy Capital Fund VIII Co-Investors, L.P. 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX77002 X EnCap Energy Capital Fund IX, L.P. 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX77002 X EnCap Partners GP, LLC 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX77002 X TPR Residual Assets, LLC 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX77002 X Signatures EnCap Energy Capital Fund VIII, L.P., By: EnCap Equity Fund VIII GP, L.P., its general partner, EnCap Investments L.P., its general partner, EnCap Investments GP, L.L.C., its general partner, /s/ Douglas E. Swanson, Jr., Managing Director 11/13/2020 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On November 13, 2020, pursuant to the Agreement and Plan of Merger dated as of August 12, 2020 (the "Merger Agreement"), by and among Montage Resources Corporation (the "Issuer") and Southwestern Energy Company ("Southwestern"), the Issuer merged with and into Southwestern, with Southwestern continuing as the surviving corporation (the "Merger"). Pursuant to the Merger Agreement, each issued and outstanding share of common stock of the Issuer, par value $0.01 per share, outstanding as of immediately prior to the effective time of the Merger was converted into the right to receive 1.8656 shares of Southwestern common stock, par value $0.01 per share ("Southwestern Common Stock"). ( 2 )On November 12, 2020 (the day prior to the effective time of the Merger), the closing price of one share of Southwestern Common Stock was $2.86. ( 3 )The reporting persons disclaim beneficial ownership of the reported securities except to the extent of such reporting person's pecuniary interest therein, and this report shall not be deemed an admission that such reporting person is the beneficial owner of the reported securities for purposes of Section 16 or for any other purpose. ( 4 )These securities were directly held by EnCap Energy Capital Fund VIII Co-Investors, L.P. ("EnCap Fund VIII Co-Invest"). EnCap Partners GP, LLC ("EnCap Partners GP") is the sole general partner of EnCap Partners, LP ("EnCap Partners"), which is the managing member of EnCap Investments Holdings, LLC ("EnCap Holdings"), which is the sole member of EnCap Investments Holdings Blocker, LLC ("EnCap Holdings Blocker"). EnCap Holdings Blocker is (i) the sole member of EnCap Investments GP, L.L.C. ("EnCap Investments GP"), which is the sole general partner of EnCap Investments L.P. ("EnCap Investments LP"), and (ii) the sole limited partner of EnCap Investments LP. EnCap Investments LP is the general partner of EnCap Equity Fund VIII GP, L.P. ("EnCap Fund VIII GP"), the sole general partner of EnCap Fund VIII Co-Invest. ( 5 )(Continued from footnote 4) Therefore, EnCap Partners GP, EnCap Partners, EnCap Holdings, EnCap Holdings Blocker, EnCap Investments GP, EnCap Investments LP and EnCap Fund VIII GP may be deemed to have beneficially owned these securities. ( 6 )These securities were directly held by EnCap Energy Capital Fund IX, L.P ("EnCap Fund IX"). EnCap Partners GP is the sole general partner of EnCap Partners, which is the managing member of EnCap Holdings, which is the sole member of EnCap Holdings Blocker. EnCap Holdings Blocker is the sole member of EnCap Investments GP, which is the sole general partner of EnCap Investments LP. EnCap Investments LP is the general partner of EnCap Equity Fund IX GP, L.P. ("EnCap Fund IX GP"), the sole general partner of EnCap Fund IX. Therefore, EnCap Partners GP, EnCap Partners, EnCap Holdings, EnCap Holdings Blocker, EnCap Investments GP, EnCap Investments LP and EnCap Fund IX GP may be deemed to have beneficially owned these securities. ( 7 )These securities were directly held by EnCap Energy Capital Fund VIII, L.P. ("EnCap Fund VIII"). EnCap Partners GP is the sole general partner of EnCap Partners, which is the managing member of EnCap Holdings, which is the sole member of EnCap Holdings Blocker. EnCap Holdings Blocker is the sole member of EnCap Investments GP, which is the sole general partner of EnCap Investments LP. EnCap Investments LP is the general partner of EnCap Equity Fund VIII GP, the sole general partner of EnCap Fund VIII Co-Invest. Therefore, EnCap Partners GP, EnCap Partners, EnCap Holdings, EnCap Holdings Blocker, EnCap Investments GP, EnCap Investments LP and EnCap Fund VIII GP may be deemed to have beneficially owned these securities. ( 8 )These securities were directly held by TPR Residual Assets, LLC ("TPR Residual"). TPR Residual is member-managed by EnCap Fund IX. Therefore, EnCap Fund IX may be deemed to have the power to vote or direct the vote or to dispose or direct the disposition of the shares owned by TPR Residual.

Remarks: This form represents an Exit Form 4 due to the merger of the Issuer with and into Southwestern.Exhibit ListExhibit 99 - Joint Filer Information

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

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