Sec Form 4 Filing - ENERGY CAPITAL PARTNERS II, LLC @ Summit Midstream Partners, LP - 2019-03-22

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

OMB APPROVAL OMB Number: 3235-0287 Expires: November 30, 2011 Estimated average burden hours per response... 0.5

1. Name and Address of Reporting Person ENERGY CAPITAL PARTNERS II, LLC 2. Issuer Name and Ticker or Trading Symbol Summit Midstream Partners, LP [ SMLP] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) X __ Other (specify below) See Footnotes (Last) (First) (Middle) 51 JOHN F. KENNEDY PARKWAY, SUITE 200 3. Date of Earliest Transaction (MM/DD/YY) 03/22/2019 (Street) SHORT HILLS, NJ07078 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 Units (Limited Partner Interests) 03/22/2019 A 8,750,000 A 40,520,408 I See footnotes ( 2 ) ( 3 ) ( 4 )

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 ENERGY CAPITAL PARTNERS II, LLC 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X X See Footnotes ENERGY CAPITAL PARTNERS II, LP 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X X ENERGY CAPITAL PARTNERS II-A, LP 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X X ENERGY CAPITAL PARTNERS II-B IP, LP 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X X ENERGY CAPITAL PARTNERS II-C (SUMMIT IP), LP 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X X Energy Capital Partners II (Summit Co-Invest), LP 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X X Signatures Energy Capital Partners II, LP By: Energy Capital Partners GP II, LP Its: General Partner By: Energy Capital Partners II, LLC Its: General Partner By: /s/ Enoch O. Varner Title: Counsel 03/26/2019 Signature of Reporting Person Date Energy Capital Partners II-A, LP By: Energy Capital Partners GP II, LP Its: General Partner By: Energy Capital Partners II, LLC Its: General Partner By: /s/ Enoch O. Varner Title: Counsel 03/26/2019 Signature of Reporting Person Date Energy Capital Partners II-B IP, LP By: Energy Capital Partners GP II, LP Its: General Partner By: Energy Capital Partners II, LLC Its: General Partner By: /s/ Enoch O. Varner Title: Counsel 03/26/2019 Signature of Reporting Person Date Energy Capital Partners II-C (Summit IP), LP By: Energy Capital Partners GP II, LP Its: General Partner By: Energy Capital Partners II, LLC Its: General Partner By: /s/ Enoch O. Varner Title: Counsel 03/26/2019 Signature of Reporting Person Date Energy Capital Partners II (Summit Co-Invest), LP By: Energy Capital Partners GP II Co-Investment (Summit), LLC Its: General Partner By: Energy Capital Partners II, LLC Its: Managing Member By: /s/ Enoch O. Varner Title: Counsel 03/26/2019 Signature of Reporting Person Date Energy Capital Partners II, LLC By: /s/ Enoch O. Varner Title: Counsel 03/26/2019 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On March 22, 2019, pursuant to that certain Equity Restructuring Agreement, dated as of February 25, 2019, the incentive distribution rights ("IDRs") and the approximately 2% general partner interest in the Issuer held by Summit Midstream GP, LLC (the "General Partner") were converted into (i) 8,750,000 newly issued common units of the Issuer and (ii) a non-economic general partner interest in the Issuer. Immediately following the issuance of the 8,750,000 common units, the General Partner distributed the units to its sole member, Summit Midstream Partners Holdings, LLC ("SMPH"). ( 2 )Following the transactions reported herein, includes 34,604,581 common units held by SMPH and 5,915,827 common units held by SMLP Holdings, LLC ("SMLP Holdings"). ( 3 )Energy Capital Partners II, LP ("ECP II") and certain of its parallel funds (collectively, the "SMLP Holdings Owners") collectively hold all of the SMPH membership interests in SMLP Holdings. Energy Capital Partners II, LLC ("ECP") indirectly controls the SMLP Holdings Owners. Accordingly, ECP and the SMLP Holdings Owners may be deemed to indirectly beneficially own the 5,915,827 common units held by SMLP Holdings but disclaim beneficial ownership except to the extent of their pecuniary interest therein. ( 4 )ECP indirectly controls ECP II, Energy Capital Partners II-A, LP ("ECP II-A"), Energy Capital Partners II-B IP, LP (''ECP II-B''), Energy Capital Partners II-C (Summit IP), LP ("ECP II-C") and Energy Capital Partners II (Summit Co-Invest), LP ("ECP Summit Co-Invest" and together with ECP II, ECP II-A, ECP II-B and ECP II-C, the ''ECP Funds''), which collectively hold more than a majority of the membership interests in Summit Midstream Partners, LLC ("Summit") and are entitled to appoint all the directors of Summit. Summit is the sole member of SMPH. Accordingly, ECP and the ECP Funds may be deemed to indirectly beneficially own the 34,604,581 common units held by SMPH but disclaim beneficial ownership except to the extent of their pecuniary interest therein.

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).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.