Sec Form 4 Filing - Oasis Petroleum Inc. @ Oasis Midstream Partners LP - 2021-03-19

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 Oasis Petroleum Inc. 2. Issuer Name and Ticker or Trading Symbol Oasis Midstream Partners LP [ OMP] 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) 1001 FANNIN ST., SUITE 1500 3. Date of Earliest Transaction (MM/DD/YY) 03/19/2021 (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 units representing limited partner interests 03/19/2021 C( 1 ) 13,750,000 ( 1 ) A 22,825,000 I See Footnotes ( 2 )

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 Subordinated units representing limited partner interests ( 1 ) 03/19/2021 C( 1 ) 13,750,000 ( 1 ) ( 1 ) Common units representing limited partner interests 13,750,000 ( 1 ) 0 I See Footnotes ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Oasis Petroleum Inc. 1001 FANNIN ST., SUITE 1500 HOUSTON, TX77002 X Oasis Petroleum LLC 1001 FANNIN STREET, SUITE 1500 HOUSTON, TX77002 X OMS Holdings LLC 1001 FANNIN STREET, SUITE 1500 HOUSTON, TX77002 X Signatures /s/ Nickolas J. Lorentzatos, Executive Vice President, General Counsel and Corporate Secretary of Oasis Petroleum Inc. 03/19/2021 Signature of Reporting Person Date /s/ Nickolas J. Lorentzatos, Executive Vice President, General Counsel and Corporate Secretary of Oasis Petroleum LLC 03/19/2021 Signature of Reporting Person Date /s/ Nickolas J. Lorentzatos, Executive Vice President, General Counsel and Corporate Secretary of OMS Holdings LLC 03/19/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On March 19, 2021, upon satisfaction of certain financial conditions for the conversion of the subordinated units representing limited partner interests of the Issuer ("Subordinated Units") set forth in the Issuer's Amended and Restated Agreement of Limited Partnership (the "Agreement"), all of the outstanding Subordinated Units automatically converted into common units representing limited partner interests of the Issuer (the "Common Units") on a one-for-one basis, pursuant to the terms of the Agreement, for no additional consideration. Upon the conversion of all of the Subordinated Units to Common Units, the Subordination Period (as defined in the Agreement) automatically terminated. ( 2 )This Form 4 is being jointly filed by OMS Holdings LLC ("OMS Holdings"), Oasis Petroleum LLC ("Oasis Petroleum") and Oasis Petroleum Inc. ("OAS"). As of March 19, 2021, OMS Holdings directly owns 22,825,000 common units, Oasis Petroleum directly owns 100% of the outstanding membership interests in OMS Holdings and OAS directly owns 100% of the outstanding membership interests in Oasis Petroleum. Accordingly, OAS and Oasis Petroleum may be deemed to be an indirect beneficial owner of the securities of the Issuer held by OMS Holdings.

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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