nwn-20260625

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 11-K

(Mark One)

[X] ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2025

[ ] TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from ___________ to____________

Commission file number 1-38681

A. Full title of the plan and the address of the plan, if different from that of the issuer named below:

NORTHWEST NATURAL GAS COMPANY

RETIREMENT K SAVINGS PLAN

B. Name of issuer of the securities held pursuant to the plan and the address of its principal executive office:

NORTHWEST NATURAL HOLDING COMPANY

250 SW Taylor Street

Portland, Oregon 97204

NORTHWEST NATURAL GAS COMPANY

RETIREMENT K SAVINGS PLAN

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			Page

Report of Independent Registered Public Accounting Firm			2

Financial Statements
Statements of Net Assets Available for Benefits at December 31, 202 5 and 202 4			3
Statements of C hanges in Net Assets Available for Benefits for the years ended December 31, 202 5 and 2024			4
Notes to Financial Statements			5

Supplemental Schedules (1)
Form 5500, Schedule H, Line 4a; Schedule of Delinquent Participant Contributions			13
Form 5500, Schedule H, Line 4i; Schedule of Assets (Held at End of Year)			14


Signatures			15

Exhibits			16

(1) Other schedules required by Section 2520.103-10 of the Department of Labor’s Rules and Regulations for Reporting and Disclosure under the Employee Retirement Income Security Act of 1974 (“ERISA”) have been omitted because they are not applicable.

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REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

Plan Administrator and Plan Participants

Northwest Natural Gas Company Retirement K Savings Plan

Opinion on the financial statements

We have audited the accompanying statements of net assets available for benefits of Northwest Natural Gas Company Retirement K Savings Plan (the “Plan”) as of December 31, 2025 and 2024, the related statements of changes in net assets available for benefits for the years then ended, and the related notes (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the net assets available for benefits of the Plan as of December 31, 2025 and 2024, and the changes in net assets available for benefits for the years then ended in conformity with accounting principles generally accepted in the United States of America.

Basis for opinion

These financial statements are the responsibility of the Plan’s management. Our responsibility is to express an opinion on the Plan’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (“PCAOB”) and are required to be independent with respect to the Plan in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Plan is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Plan’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Supplemental information

The supplemental schedule of the delinquent participant contributions for the year ended December 31, 2025 and schedule of assets (held at end of year) as of December 31, 2025 (“supplemental information”) has been subjected to audit procedures performed in conjunction with the audit of the Plan’s financial statements. The supplemental information is the responsibility of the Plan’s management. Our audit procedures included determining whether the supplemental information reconciles to the financial statements or the underlying accounting and other records, as applicable, and performing procedures to test the completeness and accuracy of the information presented in the supplemental information. In forming our opinion on the supplemental information, we evaluated whether the supplemental information, including its form and content, is presented in conformity with the Department of Labor’s Rules and Regulations for Reporting and Disclosure under the Employee Retirement Income Security Act of 1974. In our opinion, the supplemental information is fairly stated, in all material respects, in relation to the financial statements as a whole.

/s/ GRANT THORNTON LLP

We have served as the Plan’s auditor since 2012.

Philadelphia, Pennsylvania

June 25, 2026

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NORTHWEST NATURAL GAS COMPANY

RETIREMENT K SAVINGS PLAN

STATEMENTS OF NET ASSETS AVAILABLE FOR BENEFITS


	As of December 31,
	2025		2024

Assets:

Investments, at fair value	414,761,087		339,127,494

Receivables:
Notes receivable from participants	5,018,405		4,178,220


Total receivables	5,018,405		4,178,220

Total assets	419,779,492		343,305,714

Liabilities:
Other liabilities	20,035		61,390



Net assets available for benefits	$	419,759,457	$	343,244,324

The accompanying notes are an integral part of these financial statements.

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NORTHWEST NATURAL GAS COMPANY

RETIREMENT K SAVINGS PLAN

STATEMENTS OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS


	Years Ended December 31,
	2025		2024

Additions to net assets:
Investment income:
Interest and dividends	$	3,050,476	$	3,699,788
Net appreciation in fair value of investments	55,538,424		35,246,822
Net investment income	58,588,900		38,946,610

Contributions:
Participant elective and rollover	28,371,484		18,833,064
Employer	13,356,804		11,134,186
Total contributions	41,728,288		29,967,250

Interest income on notes receivable from participants	377,535		298,761



Total additions to net assets	100,694,723		69,212,621

Deductions from net assets:
Withdrawals and benefit payments	23,962,008		23,766,501
Administrative fees and expenses	217,582		201,570


Total deductions from net assets	24,179,590		23,968,071

Increase in net assets available for benefits	76,515,133		45,244,550

Net assets available for benefits:
Beginning of year	343,244,324		297,999,774
End of year	$	419,759,457	$	343,244,324

The accompanying notes are an integral part of these financial statements.

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NORTHWEST NATURAL GAS COMPANY

RETIREMENT K SAVINGS PLAN

NOTES TO FINANCIAL STATEMENTS

December 31, 2025 and 2024

1. DESCRIPTION OF PLAN

The following description of the Northwest Natural Gas Company Retirement K Savings Plan (the Plan) provides only general information. Employees and Plan participants should refer to the Plan document and summary plan description for a more comprehensive description of the Plan’s provisions.

General

The Plan is a defined contribution plan covering substantially all employees of Northwest Natural Gas Company (NW Natural), SiEnergy Holding, LLC (SiEnergy, formerly Si Investment Co, LLC) and NW Natural Renewables Holdings, LLC (collectively, the Company). NW Natural and NW Natural Renewables Holdings, LLC are wholly-owned direct subsidiaries and SiEnergy is a wholly-owned indirect subsidiary of NW Holdings.

Effective January 7, 2025, Si Investment Co, LLC was added as an adopting affiliate of the Plan. The SiEnergy, L.P. 401(k) Plan was terminated effective December 31, 2024. Beginning in 2025, eligible employees of Si Investment Co, LLC became eligible to participate in the Plan. Effective July 18, 2025, all references to Si Investment Co, LLC were updated to SiEnergy Holding, LLC to reflect the company’s name change.

Eligibility rules and entry dates vary primarily based on type of contribution and employment classification (bargaining, non-bargaining, SiEnergy Employee, regular, temporary, and term). The Plan is subject to the provisions of the Employee Retirement Income Security Act of 1974, as amended (ERISA).

NW Natural is the plan sponsor and administrator of the Plan. Fidelity Management Trust Company (Fidelity) is the Plan’s trustee. Fidelity Workplace Services, LLC performs the recordkeeping duties of the Plan.

Contributions

Under the Plan, participants may elect to contribute, subject to Internal Revenue Code (Code) limitations, up to 50% of their compensation to the Plan through salary deferral.

Participants are automatically enrolled to make pre-tax salary deferral contributions of 8% of their eligible compensation. Participants who are automatically enrolled can elect not to make contributions or to contribute a different percentage of their eligible compensation.

For participants who are making pre-tax salary deferral contributions at a rate that is greater than 0% but less than 8% of their eligible compensation, the Participant's elective contribution rate will be increased automatically by one percentage point, up to a maximum of 8% of compensation on each June 1 while the Participant continues to be an eligible employee.

For non-bargaining unit employees, NW Natural matches 60% of the first 8% of the employee's salary deferral contributions, with a maximum match of 4.8% of annual eligible compensation.

For bargaining unit employees, NW Natural matches 50% of the first 8% of the employee's salary deferral contributions, with a maximum match of 4% of annual eligible compensation, in accordance with the terms of the applicable collective bargaining agreement.

For SiEnergy employees, SiEnergy matches 100% of the first 3% of compensation contributed to the Plan by its employees and 50% of each of the next 2% for a maximum match of 4%.

Each year, NW Natural may make a supplemental contribution, the amount of which will be set by NW Natural’s Board of Directors. For the years ended December 31, 2025 and 2024, NW Natural's Board of Directors did not declare any supplemental contributions.

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Effective January 1, 2025, Section 109 of the Securing a Strong Retirement Act of 2022 ("SECURE Act 2.0") (Higher catch-up limit to apply at age 60, 61, 62, and 63) increases the catch-up contribution limit for active participants turning ages 60, 61, 62, or 63 in the calendar year to either $10,000 or 50 percent more than the regular catch-up contribution limit, whichever is greater.

Effective January 1, 2025, the Plan was amended to permit qualified student loan payments to be eligible for employer matching contributions, subject to certain conditions and limitations, as permitted under the SECURE Act 2.0.

Non-Contributory Employer Contributions

For all eligible non-bargaining unit employees hired after December 31, 2006, and all eligible bargaining unit employees hired after December 31, 2009, NW Natural will contribute 5% and 4%, respectively, of eligible annual compensation (or another amount fixed annually) as a non-contributory employer contribution for each year a participant is an active employee. These non-contributory employer contributions are invested in the same funds that have been selected by participants for salary deferral and matching contributions. If a participant has not made an investment election, the contribution will be invested in the retirement-date-based investment fund that has a projected year of retirement that corresponds closest to the year the participant turns age 65. In 2025 and 2024, non-contributory employer contributions totaled $6,093,153 and $4,888,718, respectively.

For all eligible SiEnergy employees, employer contributions of 3.65% of annual compensation up to $350,000 during the period from January 7, 2025 to December 31, 2025, plus 3.65% of annual compensation up to $350,000 January 7, 2025 to December 31, 2025 that exceeds the Social Security taxable wage base, are required for eligible employees. There are no employee contributions required under this plan.

Participant Accounts

Where applicable, each participant’s account is credited with pre-tax salary deferral contributions, matching contributions, supplemental contributions, rollover contributions, non-contributory employer contributions, and net earnings or losses. Pre-tax contributions are based on the participant’s salary deferral election. Matching contributions, supplemental, and non-contributory employer contributions are credited to the participant’s account according to the formula defined in the Plan document. Rollover contributions are credited upon receipt from the tax-qualified plan of another employer or from an Individual Retirement Account (IRA). The Plan's earnings are allocated based on account balances in the investment options selected by the participant, or in the absence of an election, the retirement-date-based investment option applicable to the participant under the Plan's terms.

Investment Options

Participants may direct contributions in any of the investment options offered by the Plan. Contributions are defaulted into the age-appropriate retirement-date-based investment until such time the participant makes active investment elections. Investment options include collective trust funds managed by BlackRock, mutual funds managed by Fidelity, and the option to invest in Northwest Natural Holding Company (NW Holdings) common stock.

Participants also have the additional choice of investing through Fidelity's BrokerageLink option which, for fees charged directly to the participant, enables the participant to select from additional investment options. The remaining investment options are managed by other parties that are not parties-in-interest. New investment elections restrict participants from allocating more than 25% to NW Holdings stock. Exchanges into NW Holdings stock are restricted when it would result in more than 25% of the participant's account value on the day of the exchange in NW Holdings stock.

Vesting

All employee contributions, employer match, supplemental contributions and associated earnings credited to participant accounts are fully vested and non-forfeitable at all times. Non-contributory employer contributions, and associated earnings, are subject to a three-year cliff vesting schedule with 100% vesting after three years of service.

Notes Receivable from Participants

Participants may borrow from their fund accounts a minimum of $1,000, up to a maximum equal to the lesser of the following amounts, reduced by the participant's highest aggregate loan balance during the 12 months preceding the loan:

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•$50,000; or

•50% of the participant's total vested account balance excluding non-contributory employer contributions.

Participants may have only one outstanding loan at a time. Participant loans are ordinarily repaid through payroll deductions and participants’ remaining account balances are used as collateral for the loans. The loans bear interest at a rate commensurate with local prevailing rates. The rate used equals the prime rate plus 1%, based on rates quoted in The Wall Street Journal on the last business day of the month prior to the loan’s inception.

Withdrawals and Payment of Benefits

On termination of service due to death, disability, retirement, or for other reasons, a participant may receive the value of his or her vested account in the following forms of payment:

•a single lump sum distribution;

•partial lump-sum distributions, up to four distributions;

•monthly, quarterly, or annual installment payments;

•a rollover to an IRA or other employer's qualified retirement plan; or

•the participant may leave the funds in the Plan.

Under the hardship withdrawal provisions of the Plan, participants may withdraw salary deferral amounts while still employed, provided the circumstances qualify as a hardship as defined in the Plan.

Participating employees can receive a distribution from the Plan due to retirement, permanent disability, termination of employment or death. Unvested balances will be forfeited in the event of termination. Participants who have terminated employment and reached a certain age are required to take minimum required distributions in accordance with the terms of the Plan and applicable law. The required minimum distribution age is 73.

For participants who have a Plan investment in NW Holdings' common stock, the Plan permits stock dividends to be distributed to the participants, independent of a termination of service or hardship, as designated by NW Natural.

Effective November 12, 2024, the Plan was amended to add four new types of withdrawals for participants who meet certain requirements. The new types of withdrawals are related to qualified births or adoptions, domestic abuse, emergency personal expenses, and qualified declared disasters.

Administrative Fees and Expenses

Certain expenses of administering and servicing the Plan are provided by NW Natural without charge to the Plan; however, each participant is charged a flat fee of $100 per year to help with the costs of audit, recordkeeping, and trustee fees, as well as investment consulting charges. Loan disbursement fees are paid by the Plan, allocated to participants withdrawing amounts as loans during the year, and are classified as administrative fees and expenses; however, each participant with a loan is also charged a flat fee of $75 per loan to help with the costs of loan processing.

Administrative fees paid to Fidelity by the Plan totaled $265,582 and $199,145 in 2025 and 2024, respectively.

Forfeitures

As of December 31, 2025 and 2024, the forfeiture account balance was $83,738 and $12,833, respectively. This balance represents amounts forfeited during the year, available to offset the employer contributions, but not yet used as of December 31 of the respective year. For the years ended December 31, 2025 and 2024, forfeitures of approximately $160,000 and $320,000 were used to offset employer contributions, respectively.

2. SIGNIFICANT ACCOUNTING POLICIES

Recently Issued or Adopted Accounting Pronouncements

There were no new issued or adopted accounting pronouncements applicable to the Plan during the years ended December 31, 2025 and 2024.

Basis of Accounting

The financial statements are prepared using the accrual basis of accounting in accordance with accounting principles generally accepted in the United States of America (GAAP).

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Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect reported amounts of assets and liabilities at the date of the financial statements and changes therein, and disclosure of contingent assets and liabilities. Actual results could differ from those estimates.

Valuation of Investments

Investments are reported at fair value. Fair value is 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. See Note 3 for discussion of fair value measurements.

Investment Transactions and Net Investment Income Recognition

Securities transactions are recorded on the date the securities are purchased or sold. Interest income is recorded as earned. Dividend income is recorded on the ex-dividend date. The cost of securities sold is determined by the average cost method.

The net appreciation in the fair value of investments presented in the statements of changes in net assets available for benefits consists of the realized gains (losses) and the unrealized appreciation (depreciation) on those investments.

Notes Receivable from Participants

Notes receivable from participants are measured at their unpaid principal balance plus any accrued but unpaid interest. Delinquent notes receivable are reclassified as distributions based upon the terms of the Plan document and reported to the Internal Revenue Service (IRS) as ordinary income.

Payment of Benefits

Benefits are recorded when paid.

3. FAIR VALUE MEASUREMENTS

In accordance with fair value accounting, the following fair value hierarchy is used for determining inputs for the

Plan assets:


Level 1			Valuation is based upon quoted prices for identical instruments traded in active markets;
Level 2			Valuation is based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant assumptions are observable in the market; and
Level 3			Valuation is generated from model-based techniques that use significant assumptions not observable in the market. These unobservable assumptions reflect our own estimates of assumptions that market participants would use in valuing the asset or liability.

When developing fair value measurements, it is the Plan's policy to use quoted market prices whenever available, or to maximize the use of observable inputs and minimize the use of unobservable inputs when quoted market prices are not available.

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

COLLECTIVE TRUST FUNDS. Valued at the daily net asset value (NAV) per unit as determined by the fund’s audited financial statements. The NAV is used as a practical expedient to estimate fair value and is based on underlying assets owned by the fund, minus its liabilities, and then divided by the number of shares outstanding.

NW NATURAL HOLDING COMPANY UNITIZED STOCK. Valued at the closing price reported on the active market on which the individual securities are traded.

MUTUAL FUNDS. Valued at NAV of shares held by the Plan. Mutual funds held by the Plan are open-end mutual funds that are registered with the Securities and Exchange Commission. These funds are required to publish their daily NAV and to transact at that price. The mutual funds held by the Plan are deemed to be actively traded.

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BROKERAGE ACCOUNTS. Participant directed investments maintained in Fidelity's BrokerageLink investment option, comprised primarily of money market and mutual funds valued at published NAV of shares held by the Plan, and common stocks valued at the closing price reported on the active market on which the individual securities are traded.

These methods may produce a fair value calculation that may not be indicative of net realizable value nor reflective of future fair values. Furthermore, although the Plan believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date.

The following tables set forth the fair value of the Plan's assets at fair value, by level and investment asset class:


	As of December 31, 2025
Asset	Level 1		Level 2		Level 3		Non-Published NAV(2)		Total

NW Natural Holding Company unitized stock	$	12,236,653	$	—	$	—	$	—	$	12,236,653
Mutual funds	40,446,472		—		—		—		40,446,472
Brokerage accounts	10,630,109		—		—		—		10,630,109
Total investments in the fair value hierarchy	63,313,234		—		—		—		63,313,234
Collective trust funds(1)	—		—		—		351,447,853		351,447,853

Total investments at fair value	$	63,313,234	$	—	$	—	$	351,447,853	$	414,761,087


	As of December 31, 2024
Asset	Level 1		Level 2		Level 3		Non-Published NAV(2)		Total

NW Natural Holding Company unitized stock	$	10,360,750	$	—	$	—	$	—	$	10,360,750
Mutual funds	35,737,764		—		—		—		35,737,764
Brokerage accounts	7,457,101		—		—		—		7,457,101
Total investments in the fair value hierarchy	53,555,615		—		—		—		53,555,615
Collective trust funds(1)	—		—		—		285,571,879		285,571,879

Total investments at fair value	$	53,555,615	$	—	$	—	$	285,571,879	$	339,127,494

(1) NW Natural believes the redemption value of the collective trust funds is likely to be the fair value, which is represented by the net asset value. A majority of the funds permit daily redemption without written notice. However, the US Treasury MM Trust B Fund allows daily redemption with 7 day written notice. There are no unfunded commitments with respect to collective trusts.

(2) The fair value for these investments is determined using NAV as of December 31, as a practical expedient, and therefore they are not classified within the fair value hierarchy. These investments primarily consist of institutional investment products, for which the NAV is generally not publicly available.

4. TERMINATION PROVISIONS

In the event of any total or partial termination or discontinuance of the Plan, the accounts of all affected participants shall become fully vested and nonforfeitable (i.e. non-contributory employer contribution account). NW Natural may continue the trust and pay benefits as they mature, or liquidate and distribute the net assets of the trust among participants and beneficiaries in proportion to their interests. NW Natural has no current plans to terminate the Plan.

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5. RELATED-PARTY AND PARTY-IN-INTEREST TRANSACTIONS

Related party transactions during the year consisted primarily of loans made to participants disclosed in Note 1 and certain of the Plan's investments are managed by the Trustee, and therefore, these transactions qualify as

party-in-interest transactions. Fees incurred by the Plan for investment manager services are included in net appreciation in the fair value of the investment.

NW NATURAL HOLDING COMPANY UNITIZED STOCK. NW Holdings unitized stock represents investments in parties-in-interest. During the years ended December 31, 2025 and 2024, purchases of NW Holdings common stock totaled 29,437 shares for $1,238,762 and 30,917 shares for $1,178,947, respectively. During the years ended December 31, 2025 and 2024, sales of NW Holdings common stock totaled 29,534 shares for $1,262,108 and 35,048 shares for $1,357,687, respectively.

As of December 31, 2025, BlackRock, Inc., The Vanguard Group, Inc. and State Street Corporation each owned beneficially more than five percent of NW Holdings common stock.

6. FEDERAL INCOME TAX STATUS

The IRS informed the Plan sponsor by a determination letter dated March 29, 2017, that the Plan was qualified and the trust established under the Plan at the time was tax-exempt, under the applicable sections of the Code. Although the Plan document has been amended since receiving the determination letter, the Plan administrator believes that the Plan is designed and is currently being operated in compliance with the applicable requirements of the Code.

Uncertain tax positions are accounted for in accordance with accounting standards that require Plan management’s assessment of the anticipated settlement outcome of material uncertain tax positions taken in a prior year, or planned to be taken in the current year. No reserves for uncertain tax positions existed as of December 31, 2025 and 2024. The Plan is subject to routine audits by taxing jurisdictions; however, there are currently no audits for any tax periods in progress.

7. RISKS AND UNCERTAINTIES

The assets of the Plan are invested in various investment securities. Investment securities are exposed to various risks such as interest rate, market, and credit risks. Due to the level of risk associated with certain investment securities, it is at least reasonably possible that changes in the values of investment securities will occur in the near term and that such changes could materially affect participants’ account balances and the amounts reported in the statements of net assets available for benefits.

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8. DELINQUENT CONTRIBUTIONS

During the plan year ending December 31, 2025, the Company had unintentional delays related to the transmission of participants' contributions to the Plan from two pay periods in 2025 at SiEnergy. The Company self-corrected the error by wiring the late contributions in 2025. See accompanying supplemental Schedule H, Line 4a; Schedule of Delinquent Participant Contributions for further information.

9. SUBSEQUENT EVENTS

Effective January 1, 2026, the Northwest Natural Gas Company Retirement K Savings Plan was renamed to Northwest Natural Retirement K Savings Plan.

Effective January 1, 2026, NW Natural Water Company, LLC (NWN Water) was added as an adopting affiliate of the Plan. Eligible employees of NWN Water and its subsidiaries, to the extent such subsidiaries have W-2 employees may participate in the Plan, beginning in 2026.

The Plan has evaluated subsequent events after the statement of net assets available for plan benefits date through June 25, 2026, the date the financial statements were issued, and there were no other subsequent events requiring adjustments to or disclosure in the financial statements.

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			NORTHWEST NATURAL GAS COMPANY RETIREMENT K SAVINGS PLAN SUPPLEMENTAL SCHEDULES

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NORTHWEST NATURAL GAS COMPANY

RETIREMENT K SAVINGS PLAN

Form 5500, Schedule H, Line 4a; Schedule of Delinquent Participant Contributions

EIN: 93-0256722 Plan 008

Year Ended December 31, 2025


Participant Contributions Transferred Late to Plan		Total that Constitute Nonexempt Prohibited Transactions
Check here if late Participant Loan Repayments are included: [ ]		Contributions Not Corrected		Contributions Corrected Outside VFCP			Contributions Pending Correction in VFCP		Total Fully Corrected Under VFCP and PTE 2002-51
$	2,761	$	—	$	2,761	*	$	—	$	—

* Represents delinquent employee contributions from two pay periods in 2025. Lost earnings on those delinquent contributions were remitted in June 2026.

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NORTHWEST NATURAL GAS COMPANY

RETIREMENT K SAVINGS PLAN

Form 5500, Schedule H, Line 4i; Schedule of Assets (Held at End of Year)

EIN: 93-0256722 Plan 008

December 31, 2025

(a)

(b)

(c)

(d)

(e)

Identity of issue, borrower, lessor or similar party

Description of investment including maturity date, rate of interest, collateral, par or maturity value

Cost
**

Current Value

***

BrokerageLink

Self-directed brokerage accounts

10,630,109

Artisan International Institutional Fund

Collective trust

10,422,766

BlackRock MSCI ACWI ex-U.S. Index Fund M

Collective trust

9,940,728

BlackRock Equity Index Fund M

Collective trust

46,977,192

BlackRock Extended Market K

Collective trust

9,901,582

BlackRock US Debt Index NL W

Collective trust

9,830,424

BlackRock LifePath Index Retirement Fund

Collective trust

39,181,151

BlackRock LifePath Index 2030 Fund

Collective trust

36,321,589

BlackRock LifePath Index 2035 Fund

Collective trust

48,520,561

BlackRock LifePath Index 2040 Fund

Collective trust

33,313,581

BlackRock LifePath Index 2045 Fund

Collective trust

37,106,003

BlackRock LifePath Index 2050 Fund

Collective trust

30,271,813

BlackRock LifePath Index 2055 Fund

Collective trust

19,359,878

BlackRock LifePath Index 2060 Fund

Collective trust

7,503,274

BlackRock LifePath Index 2065 Fund

Collective trust

1,955,977

T. Rowe Price US Treasury MM Trust B

Collective trust

10,841,334

T. Rowe Price Small-Cap Stock Fund

Mutual fund

12,852,452

American Century Small Cap Value Fund

Mutual fund

459,205

JPMorgan Equity Income Fund

Mutual fund

6,033,171

Fidelity Total Bond K6 Fund

Mutual fund

3,184,294

Fidelity Blue Chip Growth K6 Fund

Mutual fund

17,917,350

NW Natural Holding Company Unitized Stock

Common stock

12,236,653

Total investments

414,761,087

Notes Receivable from Participants

Interest rates from 4.25% to 9.5% maturing January 2026 to October 2040

5,018,405

419,779,492

* Represents identification of known party-in-interest in the Plan.

** Cost information is not required for participant-directed investments.

*** Certain investments in the BrokerageLink account are shares of mutual funds managed by Fidelity, which represents a party-in-interest in the Plan.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Northwest Natural Gas Company Retirement K Savings Plan Administrative Committee has duly caused this annual report to be signed on its behalf by the undersigned thereunto duly authorized.

NORTHWEST NATURAL GAS COMPANY RETIREMENT K SAVINGS PLAN


Dated:	June 25, 2026	/s/ Kyra Patterson
		Kyra Patterson
		Vice President and Chief People Officer
		NW Natural Gas Company
		Retirement K Savings Plan Administrative Committee