0000041719-26-000046 | 11-K | XBRL Viewer

Statements of Changes in Net Assets Available for Benefits - MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member] - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Statements of Changes in Net Assets Available for Benefits [Abstract]
Net Appreciation in Fair Value of Investments	$ 17,729,577	$ 19,133,368
Interest and Dividends	1,994,893	2,194,357
Interest on Notes Receivable from Participants	177,804	165,242
Contributions
Participants	3,855,429	4,155,439
Rollovers	2,030,764	1,011,192
Employer	78,502	2,429
Total Contributions	5,964,695	5,169,060
Benefits Paid to Participants	(25,899,100)	(21,287,816)
Administrative Expenses	(128,023)	(132,408)
Net Increase In Net Assets	(160,154)	5,241,803
Net Assets Available for Benefits
Beginning of Year	142,662,852	137,421,049
End of Year	$ 142,502,698	$ 142,662,852

Risks and Uncertainties	12 Months Ended
Dec. 31, 2025
MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]
Risks and Uncertainties [Abstract]
Risks and Uncertainties	Note 7 - Risks and Uncertainties The Plan invests in various securities including common collective trusts, money market funds, mutual funds, and the Stock Fund. Investment securities in general are exposed to various risks; such as interest rates, credit and overall market volatility. Market risks include global events which could impact the value of investment securities, such as a pandemic or international conflict. Due to the level of risk associated with certain investment securities, it is reasonably possible that changes in the value of investment securities will occur in the near term and such changes could materially affect participants’ account balances and the amounts reported in the Statements of Net Assets Available for Benefits.

Plan Termination	12 Months Ended
Dec. 31, 2025
MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]
Plan Termination [Abstract]
Plan Termination	Note 4 - Plan Termination While the Company has not expressed any intent to discontinue its contributions or terminate the Plan, it is free to do so at any time in whole or in part. In the event of a complete or partial termination of the Plan, the accounts of all affected participants become fully vested and non-forfeitable. The trustee will be directed to distribute the assets remaining in the trust fund to or for the exclusive benefit of participants or their beneficiaries in a manner in accordance with ERISA and the terms of the Plan document.

Related Party Transactions (Details) - MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member] - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Related Party Transactions [Abstract]
Investments at fair value	$ 140,378,946	$ 140,594,330
Notes receivable to participants, maximum percentage secured by the balances in the respective participants' accounts	50.00%
Stock Fund [Member]
Related Party Transactions [Abstract]
Investments at fair value	$ 124,570	210,593
Purchases made by the Plan for the investment in the Company’s common stock	0	10
Sales made by the Plan for the investment in the Company’s common stock	$ 43,581	$ 38,656

- Definition

Fair value of investment, excluding plan interest in master trust, held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Includes, but is not limited to, derivative, investment measured at net asset value per share as practical expedient, and insurance contract not meeting fully-benefit responsive investment criteria.

+ References

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+ Details

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) - Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) (Details) - MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]

12 Months Ended

Dec. 31, 2025

USD ($)

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Participant Loans

$ 2,123,752

^[1]

TOTAL

$ 142,502,698

Investment, Identifier [Axis]: Diamond Hill Small-Mid Cap Fund; Y [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Diamond Hill Small-Mid Cap Fund; Y [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Mutual Funds [Member]

Current Value

$ 1,767,242

Investment, Identifier [Axis]: Fidelity 500 Index Fund [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Party-in-interest

true

^[1]

Identity of Issuer, Borrower, Lessor, or Similar Party

Fidelity 500 Index Fund [Member]

^[1]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Mutual Funds [Member]

^[1]

Current Value

$ 26,088,555

^[1]

Investment, Identifier [Axis]: Fidelity Government Money Market Fund Premium Class [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Party-in-interest

true

^[1]

Identity of Issuer, Borrower, Lessor, or Similar Party

Fidelity Government Money Market Fund Premium Class [Member]

^[1]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Money Market Funds [Member]

^[1]

Current Value

$ 6,432,376

^[1]

Investment, Identifier [Axis]: Fidelity Intermediate Bond Fund [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Party-in-interest

true

^[1]

Identity of Issuer, Borrower, Lessor, or Similar Party

Fidelity Intermediate Bond Fund [Member]

^[1]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Mutual Funds [Member]

^[1]

Current Value

$ 2,988,865

^[1]

Investment, Identifier [Axis]: Fidelity Large Cap Growth Index Fund [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Party-in-interest

true

^[1]

Identity of Issuer, Borrower, Lessor, or Similar Party

Fidelity Large Cap Growth Index Fund [Member]

^[1]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Mutual Funds [Member]

^[1]

Current Value

$ 24,614,456

^[1]

Investment, Identifier [Axis]: Fidelity Puritan Fund; K [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Party-in-interest

true

^[1]

Identity of Issuer, Borrower, Lessor, or Similar Party

Fidelity Puritan Fund; K [Member]

^[1]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Mutual Funds [Member]

^[1]

Current Value

$ 3,478,003

^[1]

Investment, Identifier [Axis]: Fidelity US Bond Index Fund [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Party-in-interest

true

^[1]

Identity of Issuer, Borrower, Lessor, or Similar Party

Fidelity US Bond Index Fund [Member]

^[1]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Mutual Funds [Member]

^[1]

Current Value

$ 2,313,980

^[1]

Investment, Identifier [Axis]: Goldman Sachs Small/Mid Cap Growth Fund; R6 [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Goldman Sachs Small/Mid Cap Growth Fund; R6 [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Mutual Funds [Member]

Current Value

$ 1,120,687

Investment, Identifier [Axis]: Magnera Corporation [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Party-in-interest

true

^[1]

Identity of Issuer, Borrower, Lessor, or Similar Party

Magnera Corporation [Member]

^[1]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Common Stock [Member]

^[1]

Current Value

$ 124,570

^[1]

Investment, Identifier [Axis]: Schwab Indexed Retirement Trust Fund 2020 [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Schwab Indexed Retirement Trust Fund 2020 [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Common Collective Trusts [Member]

Current Value

$ 3,071,586

Investment, Identifier [Axis]: Schwab Indexed Retirement Trust Fund 2025 [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Schwab Indexed Retirement Trust Fund 2025 [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Common Collective Trusts [Member]

Current Value

$ 6,277,472

Investment, Identifier [Axis]: Schwab Indexed Retirement Trust Fund 2030 [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Schwab Indexed Retirement Trust Fund 2030 [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Common Collective Trusts [Member]

Current Value

$ 10,983,027

Investment, Identifier [Axis]: Schwab Indexed Retirement Trust Fund 2035 [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Schwab Indexed Retirement Trust Fund 2035 [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Common Collective Trusts [Member]

Current Value

$ 12,843,027

Investment, Identifier [Axis]: Schwab Indexed Retirement Trust Fund 2040 [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Schwab Indexed Retirement Trust Fund 2040 [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Common Collective Trusts [Member]

Current Value

$ 7,280,769

Investment, Identifier [Axis]: Schwab Indexed Retirement Trust Fund 2045 [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Schwab Indexed Retirement Trust Fund 2045 [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Common Collective Trusts [Member]

Current Value

$ 5,481,352

Investment, Identifier [Axis]: Schwab Indexed Retirement Trust Fund 2050 [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Schwab Indexed Retirement Trust Fund 2050 [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Common Collective Trusts [Member]

Current Value

$ 3,226,094

Investment, Identifier [Axis]: Schwab Indexed Retirement Trust Fund 2055 [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Schwab Indexed Retirement Trust Fund 2055 [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Common Collective Trusts [Member]

Current Value

$ 2,526,706

Investment, Identifier [Axis]: Schwab Indexed Retirement Trust Fund 2060 [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Schwab Indexed Retirement Trust Fund 2060 [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Common Collective Trusts [Member]

Current Value

$ 3,387,086

Investment, Identifier [Axis]: Vanguard Equity Income Admiral Shares [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Vanguard Equity Income Admiral Shares [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Mutual Funds [Member]

Current Value

$ 3,676,216

Investment, Identifier [Axis]: Vanguard Extended Market Index Fund; Institutional Shares [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Vanguard Extended Market Index Fund; Institutional Shares [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Mutual Funds [Member]

Current Value

$ 8,646,262

Investment, Identifier [Axis]: Vanguard FTSE Social Index Fund Admiral [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Vanguard FTSE Social Index Fund Admiral [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Mutual Funds [Member]

Current Value

$ 675,738

Investment, Identifier [Axis]: Vanguard Federal Money Market Fund [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Vanguard Federal Money Market Fund [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Money Market Funds [Member]

Current Value

$ 68

Investment, Identifier [Axis]: Vanguard Total International Stock Index Fund [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Identity of Issuer, Borrower, Lessor, or Similar Party

Vanguard Total International Stock Index Fund [Member]

Description of Investment including Maturity Date, Rate of Interest, Collateral, Par, or Maturity Value

Mutual Funds [Member]

Current Value

$ 3,374,809

Participant Loans [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Party-in-interest

true

^[1]

Minimum [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Participant Loans, interest rate

4.25%

^[1]

Participant Loans, maturity date

Jan. 01, 2026

^[1]

Maximum [Member]

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]

Participant Loans, interest rate

9.50%

^[1]

Participant Loans, maturity date

Dec. 31, 2037

^[1]

[1]	denotes party-in-interest

Description of Plan (Details) - MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]

12 Months Ended

Dec. 31, 2025

USD ($)

Age

Dec. 31, 2024

USD ($)

Description of Plan [Abstract]

Plan description available

true

Employees minimum period of service to be eligible to participate in the Plan

30 days

Treasure Holdco, Inc. 401(k) Plan related trust with assets merged with and into the Magnera 401(k) plan

$ 189,223,901

Maximum percentage of compensation each participant may contribute to the Plan

50.00%

Deferral rate of eligible compensation

6.00%

Minimum age participants will be eligible to make catch-up contributions (in Age) | Age

Replacement Suspense Account used

$ 1,211,358

$ 4,006,683

Replacement Suspense Account

$ 67

1,189,203

Vesting term

5 years

Vesting percentage, 3 years of service

50.00%

Amount of company contribution reduced from forfeited non-vested accounts

$ 386,122

295,840

Amount in forfeited non-vested accounts

$ 2,033

$ 79,400

Minimum age participants may withdraw amounts due to hardship (in Age) | Age

59.5

Minimum amount participants may borrow from their vested account balance

$ 1,000

Maximum amount participants may borrow from their vested account balance

$ 50,000

Maximum percentage of vested account balance participants may borrow

50.00%

Notes receivable to participants, maximum percentage secured by the balances in the respective participants' accounts

50.00%

Notes receivable from participants, spread on prime rate

1.00%

Notes receivable from participants, minimum term

1 year

Notes receivable from participants, maximum term

5 years

Notes Receivable Used for the Purchase of a Primary Residence [Member]

Description of Plan [Abstract]

Notes receivable from participants, maximum term

15 years

Magnera Corporation Stock Fund [Member]

Description of Plan [Abstract]

Maximum percentage of participants contributions that may be reallocated

15.00%

Discretionary Contributions [Member]

Description of Plan [Abstract]

Maximum percentage of compensation each participant may contribute to the Plan

3.00%

7.00%

Vesting term

3 years

Vesting percentage, 3 years of service

100.00%

Fort Smith Group [Member]

Description of Plan [Abstract]

Vesting term

3 years

Vesting percentage, less than 3 years of service

0.00%

Maximum [Member]

Description of Plan [Abstract]

Notes receivable from participants, interest rate

^[1]

9.50%

Notes receivable from participants, maturity year

^[1]

Dec. 31, 2037

Maximum [Member] | Participant Lump Sum Payment Upon Termination of Service Other Than by Retirement, Disability, or Death [Member]

Description of Plan [Abstract]

Participant vested account balance

$ 1,000

Maximum [Member] | Distribution in Direct Rollover to an Individual Retirement Account Upon Termination of Service Other Than by Retirement, Disability, or Death - in the Absence of Specific Participant Direction [Member]

Description of Plan [Abstract]

Participant vested account balance

$ 7,000

Minimum [Member]

Description of Plan [Abstract]

Notes receivable from participants, interest rate

^[1]

4.25%

Notes receivable from participants, maturity year

^[1]

Jan. 01, 2026

Minimum [Member] | Distribution in Direct Rollover to an Individual Retirement Account Upon Termination of Service Other Than by Retirement, Disability, or Death - in the Absence of Specific Participant Direction [Member]

Description of Plan [Abstract]

Participant vested account balance

$ 1,000

Minimum [Member] | Participant Assets May Remain in the Plan Upon Termination of Service Other Than by Retirement, Disability, or Death [Member]

Description of Plan [Abstract]

Participant vested account balance

$ 7,000

[1]	denotes party-in-interest

Description of Plan

12 Months Ended

Dec. 31, 2025

MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]

Description of Plan [Abstract]

Description of Plan

Note 1 - Description of Plan

General – The following description of the Magnera Corporation 401(k) Savings Plan (the “Plan”) formerly known as Glatfelter 401k Savings Plan, provides only general information. Participants should refer to the Plan document for a more complete description of the Plan’s provisions. The Plan covers all eligible employees of legacy Glatfelter Corporation’s “Corporate Group,” which includes the Charlotte, North Carolina and Pennsylvania corporate operations, its Fort Smith (“FS”) Group, its Mount Holly (“MTH”) Group, and its Jacob Holm Plan Participants (“JH”) each as defined in the Plan document, (collectively, the “Company”) who have completed 30 days service.

Merger – On November 4, 2024, Treasure Holdco, Inc., which was a wholly owned subsidiary of Berry Global Group, Inc., completed its merger with the Glatfelter Corporation which concurrently changed its name to Magnera Corporation. Subsequently, the Treasure Holdco, Inc. 401(k) Plan and its related trust with assets of $189,223,901 were merged with and into the Magnera 401(k) Savings Plan on January 1, 2026. The Plan was amended and restated effective January 1, 2026 primarily to consolidate amendments made subsequent to the last amendment and restatement of the Plan; to reflect the merger of the Treasure Holdco, Inc. 401(k) Plan with and into the Plan; to reflect changes in the design and operation of the Plan to be implemented beginning in the 2026 plan year; and to reflect additional changes as required or permitted by applicable law.

Participation – An employee is eligible to become a participant in the Plan on the first day of the calendar month coinciding with or next following the date eligibility requirements are met.

Contributions – Each year, each participant may contribute on a pre-tax basis and/or on a Roth after-tax basis, through payroll deductions, up to 50% of their compensation as defined in the Plan document. The Plan includes an auto-enrollment provision whereby all newly eligible employees are automatically enrolled in the Plan unless they affirmatively elect not to participate in the Plan. Automatically enrolled participants have their deferral rate set at 6% of eligible compensation and their contributions invested in a designated balanced fund until changed by the participant.

The Company provides a discretionary non-elective contribution to all participants (“Discretionary Contribution”). Employees are eligible after completing 30 days of service and only compensation paid after becoming eligible will count for purposes of this contribution. The discretionary contribution as a percent of eligible wages was 3% in 2025 and 7% in 2024.

Participants who have attained age 50 before the end of the plan year are eligible to make catch-up contributions. The Plan also accepts rollover contributions from other qualified defined benefit or defined contribution plans.

Eligible participants may elect to contribute a portion, or all, of certain bonuses they receive, subject to Internal Revenue Service (“IRS”) mandated maximum contributions, in addition to any payroll deduction savings and Company Discretionary Contributions described above.

Participants may allocate contributions among available investment options. Employer contributions are made in cash and participants choose the investment funds into which these cash contributions are invested. Participants can change their investment allocations at any time; however, no more than 15% of any contributions may be directed into the Magnera Corporation unitized stock fund (the "Stock Fund"). As of January 17, 2023, investment elections for contributions and transfers into the Stock Fund were prohibited

Replacement Suspense Account – In connection with the 2019 termination of the overfunded Glatfelter Retirement Plan (the “Pension Plan”), the Plan is intended to serve as a qualified replacement plan within the meaning of section 4980(d) of the Internal Revenue Code. As such, the Plan established a suspense account (the “Replacement Suspense Account”) which includes reversionary excess Pension Plan assets into the Replacement Suspense Account. Monies available in the Replacement Suspense Account will be allocated to participant accounts to fund the Discretionary Contributions discussed above in Note 1. During 2025 and 2024, $1,211,358 and $4,006,683, respectively, from the Replacement Suspense Account was used to fund employer Discretionary Contributions and the balance in the Replacement Suspense Account was $67 and $1,189,203 at December 31, 2025 and 2024, respectively.

Participant Accounts and Vesting – Participant payroll deduction contributions, rollover contributions, catch-up contributions, and profit sharing deferral contributions are fully vested upon receipt by the Plan. For Corporate Group employees, Company matching contributions are subject to a graded vesting schedule through which a participant becomes fully vested after attaining five years of service as follows:


Years of Vesting Service		Vesting Percentage
Less than 2 years		0
2 years		25
3 years		50
4 years		75
5 or more years		100

FS employees become fully vested in matching and fixed employer contributions upon attaining 3 years of service and are 0% vested until that time.

For all participants, the Company Discretionary Contributions are 100% vested after three years.

Each participant’s account is credited with or debited by, as applicable, (a) the participant’s contributions, (b) allocations of the Company’s contributions, (c) applicable earnings (losses), and (d) an allocation of any Plan administrative expenses that are paid by the Plan, each based on eligible compensation, account balances, or specific participant transactions, as defined. The benefit to which a participant is entitled is equal to the participant’s vested account.

Forfeitures - Forfeited balances of terminated participants’ non-vested accounts may be used to reduce future Company contributions, or pay Plan administrative expenses. During 2025 and 2024, Company contributions were reduced by $386,122 and $295,840, respectively, by forfeitures. At December 31, 2025 and 2024, forfeitures totaled $2,033 and $79,400, respectively.

Benefits - Upon retirement, disability or death, distributions will be paid as soon as administratively possible in a lump sum or as an annuity. Upon termination of service other than by retirement, disability, or death, a participant will receive a lump sum payment if the total of their vested account balance does not exceed $1,000. If the vested account balance exceeds $1,000, but is less than $7,000, in the absence of specific participant direction, the balance will be distributed in a direct rollover to an Individual Retirement Account of the Plan Administrator’s choosing, set up in the name of the participant. If the vested account balance exceeds $7,000, the assets may remain in the Plan until the participant’s normal or early retirement date. However, terminated participants may elect to receive their vested account balance as soon as administratively possible following termination.

In certain instances, participants may withdraw amounts for an immediate and heavy financial hardship that cannot be reasonably met from other resources or upon obtaining age 59 ½.

Notes Receivable from Participants – Participants may borrow from their accounts a minimum of $1,000 up to a maximum of the lesser of $50,000, or 50% of the participant’s vested account balance. Notes receivable are secured by up to 50% of the balance in the participant’s account. Interest is payable at rates based on the prime rate plus 100 basis points at the time the borrowing is approved. As of December 31, 2025, interest rates ranged from 4.25% to 9.5% with maturity dates ranging from 2026 to 2037. Terms range from one to five years, or up to 15 years if the note receivable is extended for the purchase of a primary residence. Notes receivable are stated at their unpaid principal plus accrued but unpaid interest.

Administrative Costs – Administrative costs of the Plan are absorbed by the Company, with certain exceptions. Expenses that are paid by the Company are excluded from these financial statements. Fees related to the administration of notes receivable from participants are charged directly to the participant’s account and are included in administrative expenses.

Accounting Policies, by Policy (Policies) - MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]	12 Months Ended
	Dec. 31, 2025
EBP, Accounting Policy [Line Items]
Basis of Presentation	*Basis of Presentation* – The financial statements of the Plan are prepared on the accrual basis of accounting.
Use of Estimates	*Use of Estimates* – The preparation of financial statements in accordance with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and changes therein, and disclosures of contingent assets and liabilities. Actual results could differ from those estimates.
Investments	*Investments* – Investments held in the Plan are stated at fair value. See Note 3 for a discussion of the fair value measurements. Purchases and sales of securities are recorded on a trade-date basis. Interest income is recorded on an accrual basis. Dividends are recorded on the ex-dividend date. Net appreciation/depreciation includes gains and losses on investments bought and sold as well as held during the year.
Payment of Benefits	*Payment of Benefits* – Benefit payments to participants are recorded when paid.
Investment Fees	*Investment Fees –* Net investment returns reflect certain fees paid by the investment funds to their affiliated investment advisors, transfer agents, and others as further described in each fund prospectus or other published documents. These fees are deducted prior to allocation of the fund's investment earnings activity and thus are not separately identifiable as an expense.
Subsequent Events	Subsequent Events – The Plan has evaluated subsequent events for potential recognition and/or disclosure through the date of issuance of these financial statements. As previously noted in Note 1, the Plan completed a merger and Plan restatement effective January 1, 2026.

- Definition

Disclosure of accounting policy for use of estimate in preparation of financial statement of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References + Details

Fair Value Measurements - Plan's Investments at Fair Value (Details) - MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member] - USD ($)

Dec. 31, 2025

Dec. 31, 2024

Fair Value Measurements [Abstract]

Investments at fair value

$ 140,378,946

$ 140,594,330

Money Market Funds [Member]

Fair Value Measurements [Abstract]

Investments at fair value

6,432,444

8,508,755

Mutual Funds [Member]

Fair Value Measurements [Abstract]

Investments at fair value

78,744,813

75,813,247

Stock Fund [Member]

Fair Value Measurements [Abstract]

Investments at fair value

124,570

210,593

Common Collective Trusts [Member]

Fair Value Measurements [Abstract]

Investments at fair value

^[1]

55,077,119

56,061,735

Level 1 [Member]

Fair Value Measurements [Abstract]

Investments at fair value

85,301,827

84,532,595

Level 1 [Member] | Money Market Funds [Member]

Fair Value Measurements [Abstract]

Investments at fair value

6,432,444

8,508,755

Level 1 [Member] | Mutual Funds [Member]

Fair Value Measurements [Abstract]

Investments at fair value

78,744,813

75,813,247

Level 1 [Member] | Stock Fund [Member]

Fair Value Measurements [Abstract]

Investments at fair value

$ 124,570

$ 210,593

[1]

In accordance with Subtopic 820-10, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Statements of Net Assets Available for Benefits.

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2025
MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]
Summary of Significant Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 2 – Summary of Significant Accounting Policies *Basis of Presentation* – The financial statements of the Plan are prepared on the accrual basis of accounting. *Use of Estimates* – The preparation of financial statements in accordance with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and changes therein, and disclosures of contingent assets and liabilities. Actual results could differ from those estimates. *Investments* – Investments held in the Plan are stated at fair value. See Note 3 for a discussion of the fair value measurements. Purchases and sales of securities are recorded on a trade-date basis. Interest income is recorded on an accrual basis. Dividends are recorded on the ex-dividend date. Net appreciation/depreciation includes gains and losses on investments bought and sold as well as held during the year. *Payment of Benefits* – Benefit payments to participants are recorded when paid. *Investment Fees –* Net investment returns reflect certain fees paid by the investment funds to their affiliated investment advisors, transfer agents, and others as further described in each fund prospectus or other published documents. These fees are deducted prior to allocation of the fund's investment earnings activity and thus are not separately identifiable as an expense. Subsequent Events – The Plan has evaluated subsequent events for potential recognition and/or disclosure through the date of issuance of these financial statements. As previously noted in Note 1, the Plan completed a merger and Plan restatement effective January 1, 2026.

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Statements of Net Assets Available for Benefits - MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member] - USD ($)

Dec. 31, 2025

Dec. 31, 2024

Investments at Fair Value

Investments at fair value

$ 140,378,946

$ 140,594,330

Notes Receivable from Participants

2,123,752

2,068,522

Net Assets Available for Benefits

142,502,698

142,662,852

Money Market Funds [Member]

Investments at Fair Value

Investments at fair value

6,432,444

8,508,755

Mutual Funds [Member]

Investments at Fair Value

Investments at fair value

78,744,813

75,813,247

Common Collective Trusts [Member]

Investments at Fair Value

Investments at fair value

^[1]

55,077,119

56,061,735

Stock Fund [Member]

Investments at Fair Value

Investments at fair value

$ 124,570

$ 210,593

[1]

Amount of asset less liability available to pay benefit of participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), including, but not limited to, aggregation of participants' individual account balances.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Related Party Transactions

12 Months Ended

Dec. 31, 2025

MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]

Related Party Transactions

Note 6 - Related Party Transactions

The Plan provides participants the election of an investment in Magnera Corporation’s common stock through the Stock Fund, a unitized company stock fund. As of December 31, 2025 and 2024, the Plan held common stock issued by the Company as follows:


	Years Ended December 31,
		2025		2024
Shares of Magnera Corporation common stock		8,138		11,383
Fair value	$	123,209	$	206,829

For the years ended December 31, 2025 and 2024, recordkeeping and investment management fees were netted against net depreciation/appreciation in the Statements of Changes in Net Assets Available for Benefits.

The following table sets forth information related to the Plan's investments in the Stock Fund.


	Years Ended December 31,
		2025		2024
Units of the Stock Fund		91,266		128,465
Per-unit price	$	1.35	$	1.61
Equivalent shares of Magnera Corporation common stock		8,138		11,383

Assets held in this fund are expressed in terms of units and not shares of stock. Each unit represents a proportionate interest in all of the assets of this fund. The value of each participant's account is determined each business day by the number of units to the participant's credit, multiplied by the current unit value. The return on the participant's investment is based on the value of units, which, in turn, is determined by the market price of Magnera Corporation common stock and by the interest earned on a percentage of the fund's market value held in a money market fund. Magnera Corporation common stock held by the Plan as of the end of 2025 and 2024 had a market value of $124,570 and $210,593, respectively, invested in the Stock Fund. A percentage of the total market value of the Stock Fund is held in a money market fund to facilitate daily participant trading.

Certain investments in the Plan are in shares of mutual funds and a money market fund that are managed by Fidelity Management Company, the trustee of the Plan.

In addition, the Plan issues notes receivable to participants, which are secured by up to 50% of the balances in the respective participants' accounts.

The above related-party transactions qualify as party-in-interest transactions. All other transactions which may be considered party-in-interest transactions relate to normal Plan management and administrative services, and the related payment of fees.

Purchases made by the Plan for the investment in the Company’s common stock amounted to $0 and $10 for the years ended December 31, 2025 and 2024, respectively. Sales made by the Plan for the investment in the Company’s common stock amounted to $43,581 and $38,656 for the years ended December 31, 2025 and 2024, respectively.

On December 14, 2022, the Compensation Committee approved an amendment to the Plan whereby, effective as of January 17, 2023, the Stock Fund was frozen to new contributions and participation.

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2025

MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]

Fair Value Measurements [Abstract]

Plan's Investments at Fair Value

The following tables set forth the Plan’s investments at fair value. Other than investments measured at net asset value, the fair value of all investments are considered Level 1 within the fair value hierarchy:


		December 31,		December 31,
		2025		2024
Level 1
Money market funds	$	6,432,444	$	8,508,755
Mutual funds		78,744,813		75,813,247
Stock fund		124,570		210,593

Total investments measured at fair value – Level 1		85,301,827		84,532,595

Common collective trusts, at net asset value (a)		55,077,119		56,061,735

Investments at fair value	$	140,378,946	$	140,594,330


(a)	In accordance with Subtopic 820-10, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Statements of Net Assets Available for Benefits.

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

- Definition

Tabular disclosure of fair value of investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), including, but not limited to, fair value measured at net asset value per share as practical expedient (NAV).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
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+ Details

Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) (Details) - MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]	12 Months Ended
	Dec. 31, 2025
Schedule H, Line 4(i) - Schedule of Assets (Held at End of Year) [Abstract]
Plan Name	Magnera Corporation 401(k) Savings Plan
Employer Idnetification Number	23-0628360
Plan Number	017

- Definition

Plan number of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), in three-digit numeric format.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Employee Retirement Income Security Act of 1974
-Number 2520
-Section 103
-Subsection 10
-Paragraph b
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-Publisher DOL-EBSA

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Employee Retirement Income Security Act of 1974
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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+ Details

Related Party Transactions - Investments in Company Common Stock Through Stock Fund (Details) - MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member] - USD ($)	Dec. 31, 2025	Dec. 31, 2024
Magnera Corporation Common Stock [Member]
Related Party Transactions [Abstract]
Shares or units (in Shares)	8,138	11,383
Fair value (in Dollars)	$ 123,209	$ 206,829
Stock Fund [Member]
Related Party Transactions [Abstract]
Shares or units (in Shares)	91,266	128,465
Per-unit price (in Dollars per share)	$ 1.35	$ 1.61
Fair value (in Dollars)	$ 124,570	$ 210,593

- Definition

+ References

+ Details

Fair Value Measurements

12 Months Ended

Dec. 31, 2025

MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]

Fair Value Measurements [Abstract]

Fair Value Measurements

Note 3 – Fair Value Measurements

The Plan measures its investments at fair value on a recurring basis in accordance with accounting principles generally accepted in the United States of America. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The framework that the authoritative guidance establishes for measuring fair value includes a hierarchy used to classify the inputs used in measuring fair value. The hierarchy prioritizes the inputs used in determining valuations into three levels. The level in the fair value hierarchy within which the fair value measurement falls is determined based on the lowest level input that is significant to the fair value measurement. The levels of the fair value hierarchy are as follows:


	Level 1	Fair value is based on unadjusted quoted prices in active markets that are accessible to the Plan for identical assets. These generally provide the most reliable evidence and are used to measure fair value whenever available.

	Level 2	Fair value is based on significant inputs, other than Level 1 inputs, that are observable either directly or indirectly for substantially the full term of the asset through corroboration with observable market data. Level 2 inputs include quoted market prices in active markets for similar assets or liabilities, quoted market prices in inactive markets for identical or similar assets, and other observable inputs.

	Level 3	Fair value is based on significant unobservable inputs. Examples of valuation methodologies that would result in Level 3 classification include option pricing models, discounted cash flows, and similar techniques.

Following is a description of the valuation methodologies used for assets measured at fair value. There have been no changes in the methodologies used at December 31, 2025 and 2024.

Quoted market prices are used to value money market and mutual fund investments. The Stock Fund is valued at the net value of participation units which are generally valued by the trustee based upon quoted market prices on a recognized securities exchange at the last reported price of the last business day of each year of the underlying assets of the unitized fund, which include common stock of the Company and a money market fund. Common collective trusts are valued at the net asset value (“NAV”) of units of a bank collective trust. The NAV, as provided by the trustee, is used as a practical expedient to estimate fair value.


		December 31,		December 31,
		2025		2024
Level 1
Money market funds	$	6,432,444	$	8,508,755
Mutual funds		78,744,813		75,813,247
Stock fund		124,570		210,593

Total investments measured at fair value – Level 1		85,301,827		84,532,595

Common collective trusts, at net asset value (a)		55,077,119		56,061,735

Investments at fair value	$	140,378,946	$	140,594,330


(a)	In accordance with Subtopic 820-10, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Statements of Net Assets Available for Benefits.

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

- Definition

The entire disclosure for fair value of investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), including, but not limited to, fair value measured at net asset value per share as practical expedient (NAV).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Tax Status (Details) - MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]	12 Months Ended
	Dec. 31, 2025
Tax Status [Abstract]
Determination letter obtained	true
Determination letter date	Apr. 06, 2017
EBP, Tax Qualification Status [Extensible Enumeration]	Qualified Plan [Member]

Description of Plan - Graded Vesting Schedule for Company Matching Contributions (Details) - MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]	12 Months Ended
	Dec. 31, 2025
Description of Plan [Abstract]
Vesting Percentage, Less than 2 years	0.00%
Vesting Percentage, 2 years	25.00%
Vesting Percentage, 3 years	50.00%
Vesting Percentage, 4 years	75.00%
Vesting Percentage, 5 or more years	100.00%

Document And Entity Information	12 Months Ended
Document And Entity Information	Dec. 31, 2025
Document Information Line Items
Entity Central Index Key	0000041719
Document Type	11-K
Document Period End Date	Dec. 31, 2025
Document Fiscal Year Focus	2025
Entity Registrant Name	MAGNERA CORPORATION
Amendment Flag	false
MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]
Document Information Line Items
Document Type	11-K
Document Period End Date	Dec. 31, 2025
Document Fiscal Year Focus	2025
Amendment Flag	false

Tax Status	12 Months Ended
Tax Status	Dec. 31, 2025
MAGNERA CORPORATION 401(K) SAVINGS PLAN [Member]
Tax Status [Abstract]
Tax Status	Note 5 - Tax Status The Plan obtained a determination letter on April 6, 2017, in which the IRS stated that the Plan, as then designed, was in compliance with the applicable requirements of the Internal Revenue Code. The Plan has been amended since receiving that determination letter. The Plan Administrator and advisors believe that the Plan is currently designed and being operated in compliance with the applicable requirements of the Internal Revenue Code and that the Plan is qualified and the related trust is exempt from taxes as of the financial statement date. Accounting principles generally accepted in the United States of America require Plan management to evaluate tax positions taken by the Plan and recognize a tax liability if the Plan has taken an uncertain position that more likely than not would not be sustained upon examination by the IRS. The Plan Administrator has analyzed the tax positions taken by the Plan, and has concluded that as of December 31, 2025, there are no uncertain positions taken or expected to be taken that would require recognition of a liability (or asset) or disclosure in the financial statements. The Plan is subject to routine audits by taxing jurisdictions; however, there are currently no audits for any tax periods in progress.