SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549


SCHEDULE 13G


UNDER THE SECURITIES EXCHANGE ACT OF 1934
Nine Energy Service, Inc.
(Name of Issuer)


Common Stock
(Title of Class of Securities)


65441V200
(CUSIP Numbers)


03/05/2026
(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:
☒   Rule 13d-1(b)
☐   Rule 13d-1(c)
☐   Rule 13d-1(d)




SCHEDULE 13G
CUSIP Number(s):
65441V200


1 Names of Reporting Persons

MacKay Shields LLC
2 Check the appropriate box if a member of a Group (see instructions)

☐  (a)
☒  (b)
3SEC Use Only
4 Citizenship or Place of Organization

DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:
5 Sole Voting Power: 0.00
6 Shared Voting Power: 1,662,134.00
7 Sole Dispositive Power: 0.00
8 Shared Dispositive Power: 1,662,134.00
9 Aggregate Amount Beneficially Owned by Each Reporting Person

1,662,134.00
10 Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

☐
11 Percent of class represented by amount in row (9)

11.91 %
12 Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person: The reporting persons are party to a voting agreement with the Issuer dated March 5, 2026. This agreement allows the reporting persons to vote up to 10% of the total voting power of all of the outstanding voting securities of the Company on such matter as of the applicable record date after giving effect to any other voting agreement between the Company and any of its shareholders. The percentage reported herein is calculated based on 13,950,000 shares of Common Stock outstanding as of March 5, 2026.


SCHEDULE 13G
CUSIP Number(s):
65441V200


1 Names of Reporting Persons

NYLI MacKay High Yield Corporate Bond Fund
2 Check the appropriate box if a member of a Group (see instructions)

☐  (a)
☒  (b)
3SEC Use Only
4 Citizenship or Place of Organization

MASSACHUSETTS
Number of Shares Beneficially Owned by Each Reporting Person With:
5 Sole Voting Power: 0.00
6 Shared Voting Power: 1,404,300.00
7 Sole Dispositive Power: 0.00
8 Shared Dispositive Power: 1,404,300.00
9 Aggregate Amount Beneficially Owned by Each Reporting Person

1,404,300.00
10 Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

☐
11 Percent of class represented by amount in row (9)

10.07 %
12 Type of Reporting Person (See Instructions)

IV

Comment for Type of Reporting Person: The reporting persons are party to a voting agreement with the Issuer dated March 5, 2026. This agreement allows the reporting persons to vote up to 10% of the total voting power of all of the outstanding voting securities of the Company on such matter as of the applicable record date after giving effect to any other voting agreement between the Company and any of its shareholders. The percentage reported herein is calculated based on 13,950,000 shares of Common Stock outstanding as of March 5, 2026.



SCHEDULE 13G

Item 1. 
(a) Name of issuer:

Nine Energy Service, Inc.
(b) Address of issuer's principal executive offices:

2001 KIRBY DRIVE, SUITE 200, HOUSTON, 77019
Item 2. 
(a) Name of person filing:

MacKay Shields LLC NYLI MacKay High Yield Corporate Bond Fund
(b) Address or principal business office or, if none, residence:

299 PARK AVENUE 32ND FLOOR New York, New York 10171
(c) Citizenship:

MacKay Shields LLC - Delaware NYLI MacKay High Yield Corporate Bond Fund - Massachusetts
(d) Title of class of securities:

Common Stock
(e) CUSIP No.:

Item 3.If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)☐   Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)☐   Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)☐   Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)☐   Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)☒   An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)☐   An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)☐   A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)☐   A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)☐   A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)☐   A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
       please specify the type of institution:
(k)☐   Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
 
Item 4.Ownership
(a) Amount beneficially owned:

MacKay Shields LLC - 1,662,134 NYLI MacKay High Yield Corporate Bond Fund - 1,404,300
(b) Percent of class:

21.98  %
(c) Number of shares as to which the person has:
  (i) Sole power to vote or to direct the vote:

MacKay Shields LLC - 0 NYLI MacKay High Yield Corporate Bond Fund - 0

  (ii) Shared power to vote or to direct the vote:

MacKay Shields LLC - 1,662,134 NYLI MacKay High Yield Corporate Bond Fund - 1,404,300

  (iii) Sole power to dispose or to direct the disposition of:

MacKay Shields LLC - 0 NYLI MacKay High Yield Corporate Bond Fund - 0

  (iv) Shared power to dispose or to direct the disposition of:

MacKay Shields LLC - 1,662,134 NYLI MacKay High Yield Corporate Bond Fund - 1,404,300

Item 5.Ownership of 5 Percent or Less of a Class.
 
Not Applicable
Item 6.Ownership of more than 5 Percent on Behalf of Another Person.
 
If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required.


MacKay Shields LLC, an investment advisor registered under Section 203 of the Investment Advisors Act of 1940 is deemed to be the beneficial owner of 1,662,134 shares of the 11.91% of the Common Stock believed to be outstanding as a result of acting as investment adviser to various clients. All calculations of percentage ownership are based on a total of 13,950,000 shares of Common Stock issued and outstanding as of March 5, 2026. The NYLI MacKay High Yield Corporate Bond Fund, a registered investment company for which MacKay Shields acts as a sub investment adviser, may be deemed to beneficially own 10.07% of the outstanding common stock of the Company. New York Life Investment Management LLC and indirect wholly owned subsidiary of New York Life and an affiliate of MacKay Shields LLC, is the manager of the NYLI MacKay High Yield Corporate Bond Fund.
Item 7.Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
 
Not Applicable
Item 8.Identification and Classification of Members of the Group.
 
Not Applicable
Item 9.Notice of Dissolution of Group.
 
Not Applicable

Item 10.Certifications:
 
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

    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.

 
MacKay Shields LLC
 Signature:Chris Fitzgerald
 Name/Title:Chief Compliance Officer
 Date:03/31/2026
 
NYLI MacKay High Yield Corporate Bond Fund
 Signature:Chris Fitzgerald
 Name/Title:Chief Compliance Officer
 Date:03/31/2026
Exhibit Information: Joint Filing Agreement Each of the undersigned hereby agrees that the foregoing statement on Schedule 13G is filed on behalf of each of the undersigned in accordance with the provisions of Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, and that all subsequent amendments to this statement on Schedule 13G with respect to the common stock of Nine Energy Services, Inc., may be filed on behalf of each of the undersigned without the necessity of filing additional joint filing agreements. The undersigned further agree that each party hereto is responsible for the timely filing of such statement on Schedule13G and any amendments thereto, and for the accuracy and completeness of the information concerning such party contained therein; provided, however, that no party is responsible for the accuracy or completeness of the information concerning any other party, unless such party knows or has reason to believe that such information is inaccurate. This Joint Filing Agreement may be signed in counterparts with the same effect as if the signature on each counterpart were upon the same instrument. IN WITNESS WHEREOF, the undersigned have executed this Agreement as of March 24, 2026. New York Life Investments Funds, on behalf of its series, NYLI MacKay High Yield Corporate Bond Fund By: /s/ Kirk C. Lehneis Name: Kirk C. Lehneis Title: President By: /s/ Rene A. Bustamante Name: Rene A. Bustamante Title: Chief Administrative Officer MacKay Shields LLC