UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

SCHEDULE 13D

(Rule 13d-101)

Information to be Included in Statements Filed Pursuant

to § 240.13d-1(a) and Amendments Thereto Filed

Pursuant to § 240.13d-2(a)

Under the Securities Exchange Act of 1934

(Amendment No. 6)

Surgery Partners, Inc.

(Name of Issuer)

Common Stock, $0.01

par value per share

(Title of Class of Securities)

86881A 100

(CUSIP Number)

Bain Capital Investors, LLC

200 Clarendon Street

Boston, MA 02116

617-516-2000

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

December 22, 2022

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.  ☐

Note. Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See § 240.13d-7 for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934, as amended (“Act”), or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

This Amendment No. 6 relates to the shares of common stock, $0.01 par value per share (the “Common Stock”), of Surgery Partners, Inc., a Delaware corporation (the “Issuer”), and amends the initial statement on Schedule 13D filed by BCPE Seminole Holdings LP on September 8, 2019, as amended by Amendment No. 1 filed on December 15, 2017, Amendment No. 2 filed on February 12, 2021, Amendment No. 3 filed on May 19, 2021, Amendment No. 4 filed on November 15, 2021 and Amendment No. 5 filed on November 23, 2022 (the “Initial Statement” and, as further amended by this Amendment No. 6, the “Statement”). Capitalized terms used but not defined herein shall have the meanings ascribed to them in the Initial Statement and unless amended and restated hereby, all information in the Initial Statement remains in effect, as supplemented hereby.

Item 2. Identity and Background

Item 2 of the Initial Statement is hereby amended and restated as follows:

Bain Capital Investors, LLC, a Delaware limited liability company (“BCI”), is the sole member of (i) BCPE Seminole GP LLC, a Delaware limited liability company (“BCPE Seminole GP”), which is the general partner of each of BCPE Seminole and BCPE Seminole IV, (ii) BCPE Seminole GP II LLC, a Delaware limited liability company (“BCPE Seminole GP II”), which is the general partner of BCPE Seminole II, and (iii) BCPE Seminole GP III LLC, a Delaware limited liability company (“BCPE Seminole GP III”), which is the general partner of BCPE Seminole III.

BCI is the general partner of Bain Capital Partners XI, L.P., a Cayman Islands exempted limited partnership (“Partners XI” and, together with the Reporting Persons, BCI, BCPE Seminole GP, BCPE Seminole GP II and BCPE Seminole GP III, the “Bain Capital Entities”), which is the general partner of Fund XI.

As a result, BCI may be deemed to share voting and dispositive power with respect to the securities held by the Reporting Persons. Voting and investment decisions with respect to securities held by the Reporting Persons are made by the managing directors of BCI.

The Reporting Persons have entered into a Joint Filing Agreement, dated December 27, 2022, pursuant to which the Reporting Persons have agreed to file this Schedule 13D jointly in accordance with the provisions of Rule 13d-1(k)(1) promulgated under the Act.

Item 3. Source and Amount of Funds or Other Consideration

Item 3 of the Initial Statement is hereby amended and supplemented to add the following:

As previously disclosed, on November 21, 2022, the Issuer and Fund XI entered into a stock purchase agreement (the “Stock Purchase Agreement”) pursuant to which the Issuer agreed to issue and sell 9,183,673 shares of Common Stock to Fund XI at a price of $24.50 per share, for an aggregate purchase price of $224,999,988.50 (the “Private Placement”).

In connection with the closing of the Private Placement on December 22, 2022 (the “Private Placement Closing”), Fund XI assigned its rights, interests and obligations under the Stock Purchase Agreement to its affiliates, BCPE Seminole III and BCPE Seminole IV. Accordingly, at the Private Placement Closing, BCPE Seminole III purchased 4,232,353 shares of Common Stock for a purchase price of $103,692,648.50, and BCPE Seminole IV purchased 4,951,320 shares of Common Stock for a purchase price of $121,307,340.00.

Effective as of December 22, 2022, BCPE Seminole transferred an aggregate of 36,175,810 shares of Common Stock to its affiliate, BCPE Seminole II, for no cash consideration.

Also on December 22, 2022, each of BCPE Seminole II, BCPE Seminole GP II, BCPE Seminole III and BCPE Seminole GP III entered into a margin loan agreement (the “Margin Loan Agreement”) with JPMorgan Chase Bank, N.A., as administrative agent, and the lenders from time to time party thereto, pursuant to which BCPE Seminole II received a loan in the amount of $198,000,000.00, and BCPE Seminole III provided a guarantee of BCPE Seminole II’s obligations (the “Margin Loan”). BCPE Seminole II pledged 36,175,810 shares of Common Stock as collateral for the ratable benefit of the lenders to secure its obligations under the Margin Loan Agreement, and BCPE Seminole III pledged 4,232,353 shares of Common Stock as collateral for the ratable benefit of the lenders to secure its guarantee under the Margin Loan Agreement (collectively, the “Pledged Shares”). The Margin Loan matures on December 22, 2025, but must be prepaid earlier upon the occurrence of certain events, including in connection with an event of default. Upon such an event of default, the lenders may sell the Pledged Shares and use the proceeds of such sale to repay amounts owed under the Margin Loan Agreement.

Item 5. Interest in Securities of the Issuer

Item 5 of the Initial Statement is hereby amended and restated as follows:

The information set forth in or incorporated by reference in Items 2, 3 and 4 and on the cover pages of this Statement is incorporated by reference in its entirety into this Item 5.

As a result of the foregoing and the relationships described in Item 2(a) of this Statement, the Reporting Persons may be deemed to beneficially own an aggregate of 58,248,249 shares of Common Stock, representing approximately 47.5% of the issued and outstanding shares of Common Stock.

Ownership percentages set forth in this Statement are based upon a total of 122,603,695 shares of Common Stock issued and outstanding, as reported by the Issuer in the prospectus supplement filed with the Securities and Exchange Commission pursuant to Rule 424(b) under the Securities Act on November 22, 2022, after giving effect to the issuance of 23,469,388 shares of Common Stock in the November 2022 Offering and 9,183,673 shares of Common Stock in the Private Placement.

Item 6. Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer

Item 6 of the Initial Statement is hereby amended and supplemented to add the following:

Registration Rights Agreement Amendment

In connection with the Private Placement Closing, on December 22, 2022 the Registration Rights Agreement was amended (the “Registration Rights Agreement Amendment”) to extend the registration rights granted thereunder to the shares purchased in the Private Placement.

References to and the description of the Registration Rights Agreement Amendment set forth above in this Item 6 do not purport to be complete and are qualified in their entirety by reference to the full text of the Registration Rights Agreement Amendment, which is attached hereto as Exhibit 10 and incorporated by reference herein.

Item 7. Material to be Filed as Exhibits

Item 7 of the Initial Statement is hereby amended and supplemented to add the following:

SIGNATURE

After reasonable inquiry and to the best of its knowledge and belief, the undersigned certifies that the information set forth in this statement is true, complete and correct.

Exhibit 9

AGREEMENT REGARDING THE JOINT FILING OF

SCHEDULE 13D

The undersigned being duly authorized thereunto, hereby execute this agreement as an exhibit to this Schedule 13D to evidence the agreement of the below-named parties in accordance with the rules promulgated pursuant to the Securities Exchange Act of 1934, as amended, to file this Schedule 13D (including amendments thereto) jointly on behalf of each such party.