MAGN Magnera Corporation

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 6)*

Magnera Corporation

(Name of Issuer)

Common Stock, $0.01 par value per share

(Title of Class of Securities)

55939A107

(CUSIP Number)

Carlson Capital, L.P.

Attn: Rahim Ibrahim

2100 McKinney Avenue, Suite 1900

Dallas TX 75201

(214) 932-9600

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

November 4, 2024

(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: ☐

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 (“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).

Explanatory Note

This Amendment No. 6 (“Amendment No. 6”) amends and supplements the statement on Schedule 13D filed with the Securities and Exchange Commission (the “SEC”) on October 17, 2022 (as amended by Amendment No. 1 to the Original Schedule 13D filed with the SEC on March 31, 2023, Amendment No. 2 to the Original Schedule 13D filed with the SEC on September 8, 2023, Amendment No. 3 to the Original Schedule 13D filed with the SEC on October 13, 2023, Amendment No. 4 to the Original Schedule 13D filed with the SEC on October 13, 2023, Amendment No. 5 to the Original Schedule 13D filed with the SEC on September 30, 2024, and this Amendment No. 6, the “Schedule 13D”) with respect to shares of common stock, par value $0.01 per share (the “Common Shares”), of Magnera Corporation (the “Issuer”). This Amendment No. 6 amends Items 3 and 5 as set forth below. Capitalized terms used herein and not otherwise defined in this Amendment No. 6 have the meanings set forth in the Schedule 13D.

Item 3. SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION

The Reporting Persons received the amounts set forth in Annex B from the purchase and sale of the Common Shares reported in this Amendment No. 6.

Item 5. INTEREST IN SECURITIES OF THE ISSUER

(a), (b) The Reporting Persons may be deemed to beneficially own in the aggregate 284,750 Common Shares. Based upon a total of 35,341,220 Common Shares outstanding as of November 4, 2024, the Reporting Persons’ shares represent approximately 0.81% of the outstanding Common Shares.

Effective November 4, 2024, and documented on the Form 8-K Magnera Corporation filed with the SEC on November 4, 2024, Glatfelter Corporation participated in a merger, effected a 1 for 13 reverse stock split, and changed its name to Magnera Corporation.

Carlson Capital, Asgard II and Mr. Carlson may be deemed to beneficially own and have the power to vote and direct the disposition of the 284,750 Common Shares reported.

OFF may be deemed to beneficially own and has the power to vote and dispose the 9,230 Common Shares reported herein as owned by it, which shares represent approximately 0.03% of the outstanding Common Shares.

DOF may be deemed to beneficially own and has the power to vote and dispose the 275,520 Common Shares reported herein as owned by it, which shares represent approximately 0.78% of the outstanding Common Shares.

(c) The Reporting Persons have not effected any transactions in the Common Shares in the last 60 days preceding November 4, 2024, other than as set forth herein on Appendix B.

(d) Except as set forth herein, no person other than the Reporting Persons 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, Common Shares.

(e) Not applicable.

The filing of this statement should not be construed as an admission that any of the Reporting Persons is, for the purposes of Section 13 of the Act, the beneficial owner of the Common Shares reported herein.

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.

Date: November 6, 2024

Appendix B

Set forth below is a list of transactions in shares of the Issuer’s Common Shares which, to the best of the knowledge of the Reporting Persons, have been effected in the past 60 days preceding November 4, 2024, in the ordinary course of business. The Reporting Persons engaged in the following open market transactions which are summarized below, to report (i) the total amount of shares that were the subject of transactions effected on each day and (ii) the price per share on each day at which the transactions were effected: