Sec Form 4 Filing - Matthews Louise E @ Summit Midstream Partners, LP - 2020-03-15

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 Matthews Louise E 2. Issuer Name and Ticker or Trading Symbol Summit Midstream Partners, LP [ SMLP] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) See remarks below. (Last) (First) (Middle) C/O SUMMIT MIDSTREAM PARTNERS, LP, 910 LOUISIANA STREET, SUITE 4200 3. Date of Earliest Transaction (MM/DD/YY) 03/15/2020 (Street) HOUSTON, TX77002 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ 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 Units 03/15/2020 M 24,703 A 50,416 D

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 Phantom Units ( 1 ) 03/15/2020 M 2,962 ( 2 ) ( 3 ) Common Units 2,962 $ 0 0 D Distribution Equivalent Rights $ 5.5875 03/15/2020 D 2,962 ( 2 ) ( 3 ) Common Units 2,962 $ 0 0 D Phantom Units ( 1 ) 03/15/2020 M 4,699 ( 4 ) ( 3 ) Common Units 4,699 $ 0 4,699 D Distribution Equivalent Rights $ 3.2875 03/15/2020 D 4,699 ( 4 ) ( 3 ) Common Units 4,699 $ 0 0 D Phantom Units ( 1 ) 03/15/2020 M 17,042 ( 5 ) ( 3 ) Common Units 17,042 $ 0 34,082 D Distribution Equivalent Rights $ 0.9875 03/15/2020 D 17,042 ( 5 ) ( 3 ) Common Units 17,042 $ 0 0 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Matthews Louise E C/O SUMMIT MIDSTREAM PARTNERS, LP 910 LOUISIANA STREET, SUITE 4200 HOUSTON, TX77002 See remarks below. Signatures /s/ Brock M. Degeyter, Attorney-in-Fact for Louise E. Matthews 03/17/2020 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each phantom unit is the economic equivalent of one common unit. ( 2 )The final one-third of the phantom units subject to the original award agreement vested on March 15, 2020, on the third anniversary of the March 15, 2017 grant date. The Reporting Person received distribution equivalent rights (DERs) for each phantom unit, providing for payment on the vesting date of a lump sum of cash equal to the accrued distributions from and after the grant date of the phantom units. ( 3 )The phantom units and associated DERs do not expire. The phantom units are settled upon vesting in common units (on a one-for-one basis) or in cash, at the discretion of the Issuer. ( 4 )One-third of the phantom units subject to the original award agreement vested on March 15, 2020, with the final one-third of the phantom units subject to vesting on the third anniversary of the March 15, 2018 grant date, subject to continued employment. The Reporting Person received DERs for each phantom unit, providing for payment on the vesting date of a lump sum of cash equal to the accrued distributions from and after the grant date of the phantom units. ( 5 )One-third of the phantom units subject to the original award agreement vested on March 15, 2020, with the remaining phantom units subject to vesting on the second and third anniversaries of the March 15, 2019 grant date, subject to continued employment. The Reporting Person received DERs for each phantom unit, providing for payment on the vesting date of a lump sum of cash equal to the accrued distributions from and after the grant date of the phantom units.

Remarks: The Reporting Person is Executive Vice President and Chief Administration Officer of Summit Midstream GP, LLC, the general partner of the Issuer (the "General Partner"). The Issuer is managed by the directors and executive officers of the General Partner.

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

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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