NORTHWEST PIPELINE LLC

Index of Combined Notes to Financial Statements

The Combined Notes to Financial Statements include information for multiple registrants, specifically The Williams Companies, Inc. (Williams), as well as Transcontinental Gas Pipe Line Company, LLC (Transco) and Northwest Pipeline LLC (NWP), both of which are wholly owned subsidiaries of Williams. References to subsidiaries by name, including equity-method investees, Transco, and NWP, refer exclusively to those businesses and operations.

The following list indicates the Registrants to which each of the combined notes apply. Specific disclosures within each combined note may apply to all Registrants unless indicated otherwise.

Note 1 – General, Description of Business, and Basis of Presentation

General

The accompanying interim financial statements do not include all the notes in the annual financial statements and, therefore, should be read in conjunction with the financial statements and combined notes thereto for the year ended December 31, 2024, in the Annual Report on Form 10-K. The accompanying unaudited financial statements include all normal recurring adjustments and others that, in the opinion of management, are necessary to present fairly the interim financial statements.

The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying combined notes. Actual results could differ from those estimates.

Description of Business

Williams is a Delaware corporation whose common stock is listed and traded on the New York Stock Exchange. Its operations are located in the United States and are presented within the following reportable segments: Transmission & Gulf of America, Northeast G&P, West, and Gas & NGL Marketing Services, consistent with the manner in which Williams’ Chief Executive Officer, the chief operating decision maker (CODM), evaluates performance and allocates resources. All remaining business activities, including upstream operations, certain new energy ventures, and corporate activities, are included in Other.

Transmission & Gulf of America is comprised of the Transco, NWP, and MountainWest Pipelines Holding LLC (MountainWest) interstate natural gas pipelines and their related natural gas storage facilities, as well as the natural gas gathering and processing and crude oil production handling and transportation assets in the Gulf Coast region, including Discovery, a former 60 percent equity-method investment in which Williams acquired the remaining ownership interest in August 2024 (see Note 3 – Acquisitions and Divestitures), a 51 percent interest in Gulfstar One LLC (Gulfstar One) (a consolidated variable interest entity, or VIE), and a 50 percent equity-method investment in Gulfstream Natural Gas System, L.L.C. (Gulfstream). Transmission & Gulf of America also includes natural gas storage facilities and pipelines providing services in north Texas, and also in Louisiana and Mississippi related to the January 2024 Gulf Coast Storage Acquisition (see Note 3 – Acquisitions and Divestitures).

Northeast G&P is comprised of Williams’ midstream gathering, processing, and fractionation businesses in the Marcellus Shale region primarily in Pennsylvania and New York, and the Utica Shale region of eastern Ohio, as well as a 65 percent interest in Ohio Valley Midstream LLC (Northeast JV) (a consolidated VIE) which operates in West Virginia, Ohio, and Pennsylvania, a 66 percent interest in Cardinal Gas Services, L.L.C. (Cardinal) (a consolidated VIE) which operates in Ohio, a 50 percent equity-method investment in Blue Racer Midstream LLC (Blue Racer), and Appalachia Midstream Investments.

West is comprised of Williams’ gas gathering, processing, and treating operations in the Rocky Mountain region of Colorado and Wyoming, the Barnett Shale region of north-central Texas, the Eagle Ford Shale region of south Texas, the Haynesville Shale region of east Texas and northwest Louisiana, the Mid-Continent region which includes the Anadarko and Permian basins, and the Denver-Julesberg Basin (DJ Basin) of Colorado. This segment also includes Williams’ NGL storage facilities, an undivided 50 percent interest in an NGL fractionator near Conway, Kansas, and a 50 percent equity-method investment in Overland Pass Pipeline Company LLC (OPPL).

Gas & NGL Marketing Services is comprised of Williams’ NGL and natural gas marketing and trading operations, which include risk management and transactions related to the storage and transportation of natural gas and NGLs on strategically positioned assets.

Transco

Transco is an interstate natural gas transmission company that owns and operates a natural gas pipeline system extending from Texas, Louisiana, Mississippi and the Gulf of America through Alabama, Georgia, South Carolina, North Carolina, Virginia, Maryland, Delaware, Pennsylvania, and New Jersey to the New York City metropolitan area. The system serves customers in Texas and the 12 southeast and Atlantic seaboard states mentioned above, including major metropolitan areas in Georgia, Washington D.C., Maryland, North Carolina, New York, New Jersey, and Pennsylvania. Transco is a single-member limited liability company, and as such, single-member losses are limited to the amount of its investment.

NWP

NWP owns and operates an interstate pipeline system for the mainline transmission of natural gas. This system extends from the San Juan Basin in northwestern New Mexico and southwestern Colorado through Colorado, Utah, Wyoming, Idaho, Oregon, and Washington to a point on the Canadian border near Sumas, Washington. NWP is a single-member limited liability company, and as such, single-member losses are limited to the amount of its investment.

Basis of Presentation

Reclassifications

Certain prior-year amounts for Transco and NWP have been reclassified to conform to the current year’s presentation. These reclassifications had no impact on Transco’s or NWP’s Net income (loss), working capital, cash flows, or Total Member’s Equity previously reported.

Accounting Standards Issued But Not Yet Adopted

In December 2023, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2023-09, Income Taxes: Improvements to Income Tax Disclosures, which requires disclosure of specific categories in the rate reconciliation and additional information for reconciling items that meet a quantitative threshold. This ASU is effective for annual periods beginning after December 15, 2024. The adoption of ASU 2023-09 is not expected to have a material impact on the financial statements.

In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures, which requires public entities to disclose additional information in the notes to financial statements for certain types of expenses (including purchases of inventory, employee compensation, depreciation, amortization, and depletion) in commonly presented expense captions (such as cost of sales, or selling, general and administrative expenses). The amendments are effective for annual periods beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027, with early adoption permitted. The impact of this standard is currently being evaluated.

Share Repurchase Program

In September 2021, Williams’ Board of Directors authorized a share repurchase program with a maximum dollar limit of $1.5 billion. Repurchases may be made from time to time in the open market, by block purchases, in privately negotiated transactions, or in such other manner as determined by management. Williams will also determine the timing and amount of any repurchases based on market conditions and other factors. The share repurchase program does not obligate Williams to acquire any particular amount of common stock, and it may be suspended or discontinued at any time. This share repurchase program does not have an expiration date. During the six months ended June 30, 2025 and 2024, there wereno repurchases under the program. Cumulative repurchases to date under the program total $139 million.

Significant Risks and Uncertainties

Management believes that the carrying value of certain of Williams’ property, plant, and equipment and intangible assets, notably certain assets acquired by Williams accounted for as business combinations between 2012 and 2014, may be in excess of current fair value. However, the carrying value of these assets, in management’s judgment, continues to be recoverable. It is reasonably possible that future strategic decisions, including transactions such as monetizing assets or contributing assets to new ventures with third parties, as well as unfavorable changes in expected producer activities, could impact management’s assumptions and ultimately result in impairments of these assets. Such transactions or developments may also indicate that certain of Williams’ equity-method investments have experienced other-than-temporary declines in value, which could result in impairment.

Note 2 – Variable Interest Entities

Consolidated VIEs

As of June 30, 2025, Williams consolidated the following VIEs:

Northeast JV

Williams owns a 65 percent interest in the Northeast JV, a subsidiary that is a VIE due to certain voting rights being disproportionate to the obligation to absorb losses and substantially all of the Northeast JV’s activities being performed on Williams’ behalf. Williams is the primary beneficiary because it has the power to direct the activities that most significantly impact the Northeast JV’s economic performance. The Northeast JV provides midstream services for producers in the Marcellus Shale and Utica Shale regions. Future expansion activity is expected to be funded with capital contributions from Williams and the other equity partner on a proportional basis.

Gulfstar One

Williams owns a 51 percent interest in Gulfstar One, a subsidiary that, due to certain risk-sharing provisions in its customer contracts, is a VIE. Gulfstar One includes a proprietary floating-production system, Gulfstar FPS, and associated pipelines that provide production handling and gathering services in the eastern deepwater Gulf of America. Williams is the primary beneficiary because it has the power to direct the activities that most significantly impact Gulfstar One’s economic performance.

Cardinal

Williams owns a 66 percent interest in Cardinal, a subsidiary that provides gathering services for the Utica Shale region and is a VIE due to certain risks shared with customers. Williams is the primary beneficiary because it has the power to direct the activities that most significantly impact Cardinal’s economic performance. Future expansion activity is expected to be funded with capital contributions from Williams and the other equity partner on a proportional basis.

The following table presents amounts included in the Consolidated Balance Sheet that are only for the use or obligation of the consolidated VIEs:

Nonconsolidated VIEs

Williams owns certain equity-method investments that are VIEs due primarily to its limited participating rights as a minority equity holder. Williams’ maximum exposure to loss is limited to the carrying value of these investments (included within Investments in the Consolidated Balance Sheet), which totaled $214 million at June 30, 2025.

Note 3 – Acquisitions and Divestitures

Crowheart Acquisition

As of December 31, 2023, Williams had an agreement regarding certain crude oil and natural gas properties in the Wamsutter basin in Wyoming under which it owned a 75 percent undivided interest in each well’s working interest and proportionally consolidated its undivided interest. On November 1, 2024, Williams closed on the acquisition of a third-party operator, Crowheart Energy, LLC, for $307 million cash, subject to working capital and post-closing adjustments. After closing on the acquisition, Williams owns more than a 90 percent working interest in each well. The purpose of this acquisition was to consolidate Williams’ interests in the Wamsutter basin and further optimize development in the area to continue to supply its gathering and processing assets. Assets acquired, acquisition-related costs incurred, and results of operations realized are included at Other.

During the period from the acquisition date of November 1, 2024 to December 31, 2024, the additional interest acquired in the Crowheart Acquisition contributed Revenues of $20 million and Modified EBITDA (as defined in Note 11 – Segment Disclosures) of $7 million.

Acquisition-related costs for the Crowheart Acquisition total $1 million and are included in Selling, general, and administrative expenses.

Williams accounted for the Crowheart Acquisition as a business combination, which requires, among other things, that identifiable assets acquired and liabilities assumed be recognized at their acquisition date fair values.

The following table presents the preliminary allocation of the acquisition date fair value of the major classes of the assets acquired and liabilities assumed at November 1, 2024. The allocation is considered preliminary because the valuation work has not been completed due to the ongoing review of the valuation results and validation of significant inputs and assumptions. Preliminary fair value measurements were made for certain acquired assets and liabilities, primarily property, plant, and equipment, which utilized the income approach for proved developed producing reserves and the market approach for undeveloped reserves; however, adjustments to those measurements may be made in subsequent periods, up to one year from the acquisition date, as new information related to facts and circumstances as of the acquisition date may be identified. After the March 31, 2025, financial statements were issued, Williams identified adjustments to the preliminary purchase price allocation, resulting in decreases of $56 million in property, plant, and equipment and $56 million in noncurrent liabilities.

Discovery Acquisition

As of December 31, 2023, Williams owned a 60 percent interest in Discovery, which it accounted for as an equity-method investment. On August 1, 2024, Williams closed on the acquisition of the remaining 40 percent interest in Discovery, along with certain other assets, for $170 million cash, subject to working capital and post-closing adjustments. As a result of acquiring this additional interest, Williams obtained control and subsequently consolidates Discovery. The purpose of this acquisition was to expand Williams’ gathering, processing, and transportation presence in the Gulf of America region. Assets acquired, acquisition-related costs incurred, and results of operations realized are included within Williams’ Transmission & Gulf of America segment.

During the period from the acquisition date of August 1, 2024 to December 31, 2024, the operations acquired in the Discovery Acquisition contributed Revenues of $144 million and Modified EBITDA of $42 million.

Acquisition-related costs for the Discovery Acquisition total $1 million, incurred in 2024, and are included in Selling, general, and administrative expenses.

Williams accounted for the Discovery Acquisition as a business combination. The book value of its existing equity-method investment prior to the acquisition date of August 1, 2024, was $381 million. Williams recognized a $127 million gain on remeasuring its existing equity-method investment to fair value included in Other investing income (loss) – net in the third quarter of 2024, which is not included in the pro forma Discovery adjustments below. Williams utilized the income approach to fair value its previous equity-method investment in Discovery.

The following table presents the preliminary allocation of the acquisition date fair value of the major classes of the assets acquired and liabilities assumed at August 1, 2024. The allocation is considered preliminary because the valuation work has not been completed due to the ongoing review of the valuation results and validation of significant inputs and assumptions. Preliminary fair value measurements were made for certain acquired assets and liabilities, primarily property, plant, and equipment, which utilized the cost approach; however, adjustments to those measurements may be made in subsequent periods, up to one year from the acquisition date, as new information related to facts and circumstances as of the acquisition date may be identified.

Gulf Coast Storage Acquisition

On January 3, 2024, Williams closed on the acquisition from Hartree Partners LP for $1.95 billion of 100 percent of a strategic portfolio of natural gas storage facilities and pipelines, located in Louisiana and Mississippi. The purpose of this acquisition was to expand Williams’ natural gas storage footprint in the Gulf Coast region. Assets acquired, acquisition-related costs incurred, and results of operations realized are included within Williams’ Transmission & Gulf of America segment. The Gulf Coast Storage Acquisition was funded with cash on hand and $100 million of deferred consideration that did not accrue interest and was paid on January 3, 2025.

During the period from the acquisition date of January 3, 2024 to December 31, 2024, the operations acquired in the Gulf Coast Storage Acquisition contributed Revenues of $228 million and Modified EBITDA of $160 million, which is impacted by acquisition-related costs. Acquisition-related costs for the Gulf Coast Storage Acquisition total $15 million, including $14 million incurred in 2024, and are included in Selling, general, and administrative expenses.

Williams accounted for the Gulf Coast Storage Acquisition as a business combination. The valuation technique used consisted of the cost approach for property, plant, and equipment.

The following table presents the allocation of the acquisition date fair value of the major classes of the assets acquired and liabilities assumed at January 3, 2024.

Supplemental Pro Forma

The following pro forma Revenues and Net income (loss) attributable to The Williams Companies, Inc. for the three and six months ended June 30, 2024, respectively, are presented as if the Crowheart Acquisition and Discovery Acquisition had been completed on January 1, 2023. These pro forma amounts are not necessarily indicative of what the actual results would have been if the acquisitions had in fact occurred on the dates or for the periods indicated, nor do they purport to project Revenues or Net income (loss) attributable to The Williams Companies, Inc. for any future periods or as of any date. These amounts do not give effect to any potential cost savings, operating synergies, or revenue enhancements to result from the transactions or the potential costs to achieve these cost savings, operating synergies, and revenue enhancements.

Sale of Aux Sable Interest

On August 1, 2024, Williams completed the sale of its equity-method investments in Aux Sable Liquid Products Inc., Aux Sable Liquid Products LP, and Aux Sable Midstream LLC in its Northeast G&P segment for total consideration of $161 million. As a result of this sale, Williams recorded a gain of $149 million reflected in Other investing income (loss) – netin the third quarter of 2024.

Note 4 – Related Party Transactions

Transco and NWP Affiliate Transactions

Cash Management Program

Transco and NWP are participants in Williams’ cash management program, and thus make advances to and receive advances from Williams. Advances to Williams are represented by demand notes and are classified as Trade accounts and other receivables -Advances to affiliate in the Balance Sheet. Advances from Williams are classified as Payables - Advances from affiliate. Advances are stated at the historical carrying amounts.

Interest expense and income are recognized when earned and the collectability is reasonably assured. The interest rate on intercompany demand notes is based upon the daily overnight investment rate paid on Williams’ excess cash at the end of each month, which was approximately 4 percent at June 30, 2025. Interest income is included in Interest income in the Statement of Net Income for Transco and Other income (expense) – net in the Statement of Net Income for NWP.

Other Affiliate Transactions

Revenues received from affiliates are included in Transco’s Total revenuesin the Statement of Net Income. Costs of gas purchased from affiliates are included in Transco’s Natural gas product costsin the Statement of Net Income. All gas purchases are made at market or contracted prices.

Services necessary to operate Transco and NWP are provided by Williams and certain affiliates of Williams. Transco and NWP reimburse Williams and its affiliates for all direct and indirect expenses incurred or payments made (including salary, bonus, incentive compensation, and benefits) in connection with these services. Employees of Williams also provide general, administrative, and management services, and Transco and NWP are charged for certain administrative expenses incurred by Williams. These charges are either directly assigned or allocated. Allocated charges are specific or general. Specific allocations are based on a relationship with the delivery of services and general allocations are based on a three-factor formula, which considers revenues; property, plant, and equipment; and payroll. In management’s estimation, the allocation methodologies used are reasonable and result in a reasonable allocation of costs of doing business incurred by Williams. Transco and NWP have recorded for these service expenses, which are primarily included in Operating and maintenance expensesand Selling, general, and administrative expenses in the Statement of Net Income.

Transco provided services to certain of its affiliates. Transco recorded reductions in operating expenses for services provided to and reimbursed by affiliates of $3 million and $6 million for three and six months ended June 30, 2024, respectively. No such costs were incurred for the three and six months ended June 30, 2025.

During July 2025, Transco and NWP declared and paid cash distributions of $301 million and $42 million, respectively, to Williams, and Williams made a cash contribution to NWP of $50 million.

Note 5 – Revenue Recognition

Revenue by Category

The following tables present Williams’ revenue disaggregated by major service line:

(1)Revenues not derived from contracts with customers primarily consist of physical product sales related to commodity derivative contracts, realized and unrealized gains and losses associated with Williams’ commodity derivative contracts, which are reported in Net gain (loss) from commodity derivativesin the Consolidated Statement of Income, management fees received for certain services provided to operated equity-method investments, and leasing revenues associated with the Williams headquarters building.

(2)Other adjustments reflect certain costs of Gas & NGL Marketing Services’ risk management activities. As Williams is acting as agent for natural gas marketing customers or engages in energy trading activities, the resulting revenues are presented net of the related costs of those activities in the Consolidated Statement of Income.

For Transco and NWP, revenue disaggregation by major service line includes Natural gas transportation, Natural gas storage, Natural gas product sales, and Other, which are separately presented in their Statements of Net Income.

Contract Assets

The following tables present a reconciliation of contract assets:

Contract Liabilities

The following tables present a reconciliation of contract liabilities:

Remaining Performance Obligations

Remaining performance obligations primarily include reservation charges on contracted capacity for Williams’ gas pipeline firm transportation contracts with customers, storage capacity contracts, long-term contracts containing MVC associated with midstream businesses, and fixed payments associated with offshore gathering and transportation. For Williams’ interstate natural gas pipeline businesses, including Transco and NWP, remaining performance obligations generally reflect the expected rates for such services for the life of the related contracts; however, these rates may change based on future tariffs approved by the FERC and the amount and timing of these changes are not currently known.

Remaining performance obligations exclude variable consideration, including contracts with variable consideration for which it has elected the practical expedient for consideration recognized in revenue as billed. Certain of its contracts contain evergreen and other renewal provisions for periods beyond the initial term of the contract. The remaining performance obligation amounts as of June 30, 2025, do not consider potential future performance obligations for which the renewal has not been exercised and exclude contracts with customers for which the underlying facilities have not received FERC authorization to be placed into service. Consideration received prior to June 30, 2025, that will be recognized in future periods is also excluded from its remaining performance obligations and is instead reflected in contract liabilities.

The following tables present the amount of the contract liabilities balance expected to be recognized as revenue when performance obligations are satisfied and the transaction price allocated to the remaining performance obligations under certain contracts as of June 30, 2025.

Accounts Receivable

The following is a summary of Williams’Trade accounts and other receivables:

Transco and NWP receivables from contracts with customers are included within Receivables - Trade and Receivables - Affiliates. Receivables that are not related to contracts with customers are included within Receivables - Advances to affiliate and Receivables - Other.

Note 6 – Provision (Benefit) for Income Taxes

Williams’Provision (benefit) for income taxes includes:

The effective income tax rates for the total provision (benefit) for the three and six months ended June 30, 2025 and 2024, are greater than the federal statutory rate, primarily due to the effect of state income taxes.

On July 4, 2025, the One Big Beautiful Bill Act was enacted. While Williams continues to evaluate certain impacts of the new law, it does expect a temporary deferral of upcoming federal income tax payments. The new law is not expected to have a significant impact on Williams’ federal income tax provision for the 2025 full-year period.

Note 7 – Debt and Banking Arrangements

Issuances

Williams’ senior unsecured public debt issuances for 2025 are as follows:

Retirements

Williams’ senior unsecured public debt retirements for 2025 are as follows:

Credit Facility

Williams, Transco and NWP are party to a credit agreement with aggregate commitments available of $3.75 billion. In the second quarter of 2025, the maturity date of our Credit Agreement was extended one year and now expires October 8, 2028. Transco and NWP are each able to borrow up to $500 million under the credit facility to the extent not otherwise utilized by the other co-borrowers.

(1)In managing its available liquidity, Williams does not expect a maximum outstanding amount in excess of the capacity of its credit facility inclusive of any outstanding amounts under the commercial paper program.

Commercial Paper Program

At June 30, 2025, no commercial paper was outstanding under our commercial paper program.

Note 8 – Fair Value Measurements and Guarantees

The following table presents, by level within the fair value hierarchy, certain of Williams’, Transco’s, and NWP’s significant financial assets and liabilities. The carrying values of cash and cash equivalents, accounts receivable, accounts payable, and commercial paper approximate fair value because of the short-term nature of these instruments. Therefore, these assets and liabilities are not presented in the following table.

(1)The carrying amount is presented net of counterparty offsetting arrangements and collateral (see Note 9 – Commodity Derivatives).

Fair Value Methods

The following methods and assumptions are used in estimating the fair value of financial instruments:

Assets Measured at Fair Value on a Recurring Basis

ARO Trust investments

Transco is entitled to collect rates in the amounts necessary to fund its future asset retirement obligations (AROs) and deposits a portion of the collected rates into an external trust (ARO Trust). The ARO Trust invests in a moderate risk portfolio of actively traded mutual funds that are measured at fair value on a recurring basis based on quoted prices in an active market and is reported in Regulatory assets, deferred charges, and other in Williams’ Consolidated Balance Sheet and in Deferred charges and otherin the Transco Balance Sheet. The Money Market Funds held in the ARO Trust are considered investments. Both realized and unrealized gains and losses are ultimately recorded to the ARO regulatory asset.

Effective March 1, 2025, the annual funding obligation is approximately $64 million, with deposits made monthly.

Transco investments within the ARO Trust were as follows:

Commodity derivatives

Williams’ commodity derivatives include exchange-traded contracts and over-the-counter (OTC) contracts, which consist of physical forwards, futures, and swaps that are measured at fair value on a recurring basis. Williams also has other derivatives related to asset management agreements and other contracts that require physical delivery. Derivatives classified as Level 1 are valued using New York Mercantile Exchange (NYMEX) futures prices. Derivatives classified as Level 2 are valued using basis transactions that represent the cost to transport natural gas from a NYMEX delivery point to the contract delivery point. These transactions are based on quotes obtained either through electronic trading platforms or directly from brokers. Derivatives classified as Level 3 are valued using a combination of observable and unobservable inputs. See Note 9 – Commodity Derivatives for additional information.

Additional Fair Value Disclosures

Long-term debt, including current portion

The disclosed fair value of long-term debt is determined primarily by a market approach using broker quoted indicative period-end bond prices. The quoted prices are based on observable transactions in less active markets for the debt or similar instruments. The fair values of the financing obligations associated with Transco’s Dalton, Leidy South, and Atlantic Sunrise projects, as well as the deferred consideration obligation associated with the Gulf Coast Storage Acquisition (see Note 3 – Acquisitions and Divestitures), all included within long-term debt including current portion, were determined using an income approach.

Guarantees

Guarantees primarily consist of a guarantee Williams has provided in the event of nonpayment by a previously owned communications subsidiary, Williams Communications Group, Inc., (WilTel), on a lease performance obligation that extends through 2042. Guarantees also include an indemnification related to a disposed operation.

To estimate the fair value of the WilTel guarantee, an estimated default rate is applied to the sum of the future contractual lease payments using an income approach. The estimated default rate is determined by obtaining the average cumulative issuer-weighted default rate based on the credit rating of WilTel’s current owner and the term of the underlying obligation. The default rate is published by Moody’s Investors Service. The carrying value of the WilTel guarantee is reported in Other current liabilities. The maximum potential undiscounted liquidity exposure is approximately $21 million at June 30, 2025. The exposure declines systematically through the remaining term of WilTel’s obligation.

The fair value of the guarantee associated with the indemnification related to a disposed operation was estimated using an income approach that considered probability-weighted scenarios of potential levels of future performance. The terms of the indemnification do not limit the maximum potential future payments associated with the guarantee. The carrying value of this guarantee is reported in Regulatory liabilities, deferred income, and other.

Williams is required by its revolving credit agreement to indemnify lenders for certain taxes required to be withheld from payments due to the lenders and for certain tax payments made by the lenders. The maximum potential amount of future payments under these indemnifications is based on the related borrowings and such future payments cannot currently be determined. These indemnifications generally continue indefinitely unless limited by the underlying tax regulations and haveno carrying value. Williams has never been called upon to perform under these indemnifications and there is no current expectation of a future claim.

Note 9 – Commodity Derivatives

Williams is exposed to commodity price risk and utilizes derivatives to manage a portion of that risk. Williams reports the fair value of commodity derivatives in Derivative assets; Regulatory assets, deferred charges, and other; Derivative liabilities; or Regulatory liabilities, deferred income, and other. These amounts are presented on a net basis by counterparty and reflect the netting of asset and liability positions permitted under the terms of master netting arrangements and cash held on deposit in margin accounts that Williams has received or remitted to collateralize certain derivative positions. See Note 8 – Fair Value Measurements and Guarantees for additional fair value information. In Williams’ Consolidated Statement of Cash Flows, any cash impacts of settled commodity derivatives are recorded as operating activities.

Williams enters into commodity derivatives to economically hedge exposures to natural gas, NGLs, and crude oil and retains exposure to price changes that can, in a volatile energy market, be material and can adversely affect its results of operations.

Volumes

At June 30, 2025, the notional volume of the net long (short) positions for Williams’ commodity derivative contracts were as follows:

Financial Statement Presentation

The fair value of commodity derivatives, which are not designated as hedging instruments for accounting purposes, is reflected as follows:

The pre-tax impacts of Williams’ commodity derivatives, which are not designated as hedging instruments for accounting purposes, are reflected as follows:

Contingent Features

Generally, collateral may be provided in the form of a parent guaranty, letter of credit, or cash. If collateral is required, fair value amounts recognized for the right to reclaim cash collateral or the obligation to return cash collateral are offset against fair value amounts recognized for derivatives executed with the same counterparty.

Williams has specific trade and credit contracts that contain minimum credit rating requirements. These credit rating requirements typically give counterparties the right to suspend or terminate credit if Williams’ credit ratings are downgraded to non-investment grade status. Under such circumstances, Williams would need to post collateral to continue transacting business with these counterparties. At June 30, 2025, the contractually required collateral in the event of a credit rating downgrade to non-investment grade status was $9 million.

Williams maintains accounts with brokers or the clearing houses of certain exchanges to facilitate financial derivative transactions. Based on the value of the positions in these accounts and the associated margin requirements, Williams may be required to deposit cash into these accounts. At June 30, 2025 and December 31, 2024, net cash collateral held on deposit in broker margin accounts was $269 million, and $288 million, respectively.

Note 10 – Contingencies

Royalty Matters

Certain customers, including Expand Energy Corporation (formerly Chesapeake Energy Corporation or Chesapeake), have been named in various lawsuits alleging underpayment of royalties and claiming, among other things, violations of anti-trust laws and the Racketeer Influenced and Corrupt Organizations Act. Williams has also been named as a defendant in certain of these cases filed in Pennsylvania based on allegations that Williams improperly participated with Chesapeake in causing the alleged royalty underpayments. Williams believes that the claims asserted are subject to indemnity obligations owed to Williams by Chesapeake, which obligations survived Chesapeake’s bankruptcy proceedings. Prior to its bankruptcy, Chesapeake reached a settlement to resolve substantially all Pennsylvania royalty cases pending. During the pendency of the bankruptcy, that settlement was renegotiated. The settlement applies to both Chesapeake and Williams and does not require any contribution from Williams. On August 23, 2021, after referral to the United States District Court for the Southern District of Texas by the bankruptcy court, the court approved the settlement. Two objectors filed an appeal with the United States Court of Appeals for the Fifth Circuit. On June 8, 2023, the Court of Appeals vacated the settlement approval and remanded to the United States District Court for the Southern District of Texas with instructions to dismiss the settlement proceedings for lack of jurisdiction. On August 31, 2023, the bankruptcy court entered an order finding the settlement agreements to be null and void. Certain plaintiffs have filed a notice of dismissal of their claims against Chesapeake that arose prior to February 8, 2021, in the United States District Court for the Middle District of Pennsylvania lawsuits. The notice states that plaintiffs are not releasing their claims against the other defendants, including Williams, or claims against Chesapeake that arose after February 9, 2021. Williams continues to believe the claims against Williams are subject to indemnity obligations owed to Williams by Chesapeake.

Rate Matters

On August 30, 2024, Transco filed a general rate case with the FERC for an overall increase in rates and to comply with the terms of the settlement of its prior rate case. On September 30, 2024, the FERC issued an order accepting and suspending Transco’s general rate filing to be effective March 1, 2025, subject to refund and the outcome of hearing procedures established by the FERC. The order also accepted rate decreases for certain services to be effective as of October 1, 2024. Transco has provided a reserve for rate refunds, which it believes is adequate for any refunds that may be required.

Construction Litigation

In February 2025, Transco received an adverse judgment related to litigation in the United States Bankruptcy Court for the District of Delaware involving a contractor for the construction of Transco’s Atlantic Sunrise project completed in 2018. The total award to a contractor, estimated at $110 million, included amounts for unpaid invoices, interest, and attorney fees. Management estimates the probable loss from the judgment to be substantially less and Transco has filed a notice of appeal. Transco has capitalized the amount considered probable within noncurrent assets and expects any additional probable loss would also be capitalized. Transco also expects to recover approximately 29 percent of any amount paid from the co-owner of the project.

Environmental Matters

The EPA, other federal agencies, and various state regulatory agencies routinely propose and promulgate new rules, issue updated guidance to rules, or revise existing rules. These rulemakings include, but are not limited to, reviews and updates to the National Ambient Air Quality Standards, and promulgation of rules for new and existing source performance standards for certain equipment emitting volatile organic compound and methane as well as limitations on emissions of greenhouse gas compounds. Regulatory changes are continuously monitored including how they may impact operations. Implementation of new or revised regulations may result in impacts to operations and increase the cost of additions to Property, plant, and equipment – net for both new and existing facilities in affected areas; however, due to regulatory uncertainty on final rule content or guidance and applicability timeframes, the cost of these regulatory impacts is not known at this time.

Williams is a participant in certain environmental activities in various stages including assessment studies, cleanup operations, and/or remedial processes at certain sites, some of which Williams currently does not own. Williams is monitoring these sites in a coordinated effort with other potentially responsible parties, the EPA, or other governmental authorities. Williams is jointly and severally liable along with unrelated third parties in some of these activities and solely responsible in others. Certain of Williams’ subsidiaries have been identified as potentially responsible parties at various Superfund and state waste disposal sites. In addition, these subsidiaries have incurred, or are alleged to have incurred, various other hazardous materials removal or remediation obligations under environmental laws. At June 30, 2025, Williams has accrued liabilities totaling $42 million for these matters, as discussed below. Estimates of the most likely costs of cleanup are generally based on completed assessment studies, preliminary results of studies, or Williams’ experience with other similar cleanup operations. At June 30, 2025, certain assessment studies were still in process for which the ultimate outcome may yield different estimates of most likely costs. Therefore, the actual costs incurred will depend on the final amount, type, and extent of contamination discovered at these sites, the final cleanup standards mandated by the EPA or other governmental authorities, and other factors.

Continuing operations

Williams’ interstate gas pipelines are involved in remediation and monitoring activities related to certain facilities and locations for polychlorinated biphenyls, mercury, and other hazardous substances. These activities have involved the EPA and various state environmental authorities, resulting in Williams’ identification as a potentially responsible party at various Superfund waste sites. At June 30, 2025, Williams has accrued liabilities of $11 million (see Transco and NWP below) for these costs and expect to recover approximately $3 million through rates.

Williams also accrues environmental remediation costs for natural gas underground storage facilities, primarily related to soil and groundwater contamination. At June 30, 2025, Williams has accrued liabilities totaling $7 million for these costs.

Former operations

Williams has potential obligations in connection with assets and businesses it no longer operates. These potential obligations include remediation activities at the direction of federal and state environmental authorities and the indemnification of the purchasers of certain of these assets and businesses for environmental and other liabilities existing at the time the sale was consummated. At June 30, 2025, Williams has accrued environmental liabilities of $24 million related to these matters.

Transco

Transco has had studies underway for many years to test some of its facilities for the presence of toxic and hazardous substances such as polychlorinated biphenyls (PCBs) and mercury to determine to what extent, if any, remediation may be necessary. Transco has also similarly evaluated past on-site disposal of hydrocarbons at a number of its facilities. Transco has worked closely with and responded to data requests from the EPA and state agencies regarding such potential contamination of certain of their sites. Transco is conducting environmental assessments and implementing a variety of remedial measures that may result in increases or decreases in the total estimated costs. Transco also has a program for monitoring certain environmental activities at their Eminence storage facility. At June 30, 2025, Transco has accrued liabilities of approximately $10 million for the expected ongoing remediation and monitoring costs.

Transco has been identified as a potentially responsible party (PRP) at various Superfund and state waste disposal sites. Based on present volumetric estimates and other factors, their estimated aggregate exposure for remediation of these sites is less than $1 million. The estimated remediation costs for all of these sites are included in the environmental liabilities discussed above. Liability under the Comprehensive Environmental Response, Compensation and Liability Act and applicable state law can be joint and several with other PRPs. Although volumetric allocation is a factor in assessing liability, it is not necessarily determinative; thus, the ultimate liability could be substantially greater than the amounts described above.

Transco considers prudently incurred environmental assessment and remediation costs and the costs associated with compliance with environmental standards to be recoverable through rates. Historically, with limited exceptions, it has been permitted recovery of environmental costs, and it is Transco’s intent to continue seeking recovery of such costs through future rate filings.

NWP

Beginning in the mid-1980s, NWP evaluated many of its facilities for the presence of toxic and hazardous substances to determine to what extent, if any, remediation might be necessary. NWP identified PCB contamination in air compressor systems, soils, and related properties at certain compressor station sites. Similarly, it identified hydrocarbon impacts at these facilities due to the former use of earthen pits, lubricating oil leaks or spills, and excess pipe coating released to the environment. In addition, heavy metals have been identified at these sites due to the former use of mercury containing meters and paint and welding rods containing lead, cadmium, and arsenic. The PCBs were remediated pursuant to a Consent Decree with the EPA in the late 1980s, and NWP conducted a voluntary clean-up of the hydrocarbon and mercury impacts in the early 1990s. In 2005, the Washington Department of Ecology required NWP to re-evaluate previous clean-ups in Washington. During 2006 to 2015, 129 meter stations were evaluated, of which 82 required remediation. As of June 30, 2025, two meter stations are still being remediated. During 2006 to 2018, 14 compressor stations were evaluated, of which 11 required remediation. As of June 30, 2025, four compressor stations are still being remediated. NWP had accrued liabilities totaling approximately $1 million at June 30, 2025 for the ongoing remediation. NWP is conducting environmental assessments and implementing a variety of remedial measures that may result in increases or decreases in the total estimated costs.

Environmental expenditures are expensed or capitalized depending on their future economic benefit and potential for rate recovery. NWP believes that, with respect to any expenditures required to meet applicable standards and regulations, the FERC would grant the requisite rate relief so that substantially all of such expenditures would be permitted to be recovered through rates.

Washington State Climate Commitment Act

In 2021, the state of Washington passed its Climate Commitment Act establishing a market-based cap-and-invest program to reduce carbon emissions. This program took effect on January 1, 2023, and sets a limit, or cap, on overall carbon emissions in the state and requires businesses like NWP to obtain allowances equal to their annual covered carbon emissions. The state’s cap will be reduced over time to meet the state’s carbon emissions reduction targets, which means fewer carbon emissions allowances will be available to purchase each year. These allowances can be purchased through quarterly auctions hosted by the state or bought and sold on a secondary market. In 2023, NWP began purchasing allowances for the carbon emissions from nine of its thirteen compressor stations within the state whose annual carbon emissions have exceeded 25,000 metric tons of carbon dioxide equivalent at least once since 2015. NWP also began purchasing allowances for NWP’s delivery of natural gas to certain of their customers and certain of their facilities in the state whose annual carbon emissions are insufficient to require their direct participation in the program. NWP’s latest rate case settlement allows them to recover the costs of purchasing allowances under the program in their next rate case.

At June 30, 2025 and December 31, 2024, a total of $54 million and $38 million, respectively, were included in Regulatory assets and was comprised of the cost of the purchased allowances held, the estimated difference between the allowances held and the allowances required, and the interest income component of the regulatory asset. At June 30, 2025 and December 31, 2024, $4 million and $3 million, respectively, were recorded in Other current liabilities as the estimated difference. Interest income of $2 million for the six months ended June 30, 2025, and $1 million for the six months ended June 30, 2024, is reflected in Other income (expense) – net.

Other Divestiture Indemnifications

Pursuant to various purchase and sale agreements relating to divested businesses and assets, Williams has indemnified certain purchasers against liabilities that they may incur with respect to the businesses and assets acquired. The indemnities provided to the purchasers are customary in sale transactions and are contingent upon the purchasers incurring liabilities that are not otherwise recoverable from third parties.

At June 30, 2025, other than as previously disclosed, Williams is not aware of any material claims against it involving the above-described indemnities. Any claim for indemnity brought against Williams in the future may have a material adverse effect on Williams’ results of operations in the period in which the claim is made.

In addition to the foregoing, various other proceedings are pending against Williams that are incidental to its operations, none of which are expected to be material to Williams’ expected future annual results of operations, liquidity, and financial position.

Summary

Williams, Transco, and NWP have disclosed estimated ranges of reasonably possible losses for certain matters above, as well as all significant matters for which they are unable to reasonably estimate a range of possible loss. Williams, Transco, and NWP estimate that for all other matters for which they are able to reasonably estimate a range of loss, the aggregate reasonably possible losses beyond amounts accrued are immaterial to expected future annual results of operations, liquidity, and financial position. These calculations have been made without consideration of any potential recovery from third parties.

Note 11 – Segment Disclosures

Williams’ reportable segments are Transmission & Gulf of America, Northeast G&P, West, and Gas & NGL Marketing Services. All remaining business activities are included in Other. (See Note 1 – General, Description of Business, and Basis of Presentation.)

Performance Measurement

Williams’ CODM is the Chief Executive Officer. Williams’ CODM primarily utilizes Modified EBITDA, its measure of segment profit and loss, to evaluate performance and make decisions on capital allocation and human resources. Such evaluation includes periodic comparisons of actual performance versus historical and budget, as well as projections of Modified EBITDA.

Williams defines Modified EBITDAof reportable segments as follows:

•Income (loss) before income taxes excluding:

◦Contributions from upstream operations, corporate, and other business activities;

◦Depreciation, depletion, and amortization expenses;

◦Equity earnings (losses);

◦Other investing income (loss)– net;

◦Interest expense; and

◦Accretion expense associated with AROs for nonregulated operations.

•This measure is further adjusted to include Williams’ proportionate share (based on ownership interest) of Modified EBITDA from its equity-method investments, including its indirect share from interests owned by equity-method investees, calculated consistently with the definition described above.

Significant noncash items which are components of Modified EBITDAmay include net unrealized gain (loss) from commodity derivatives within Total revenues, net unrealized gain (loss) from commodity derivatives within Net processing commodity expenses for Williams’ Gas & NGL Marketing Services segment, charges associated with lower of cost or net realizable value adjustments to the Gas & NGL Marketing Services segment inventory within Product sales (for natural gas marketing inventory as these sales are presented net of the related costs) and Product costs(for NGL marketing inventory), and impairments of certain assets within Other (income) expense – net within Operating income (loss).

Intersegment Service revenues primarily represent transportation services provided to Williams’ marketing business and gathering services provided to its oil and gas properties. Intersegment Product sales primarily represent the sale of natural gas and NGLs from Williams’ natural gas processing plants and its oil and gas properties to its marketing business.

Segment assets include Investments, Property, plant, and equipment – net, and Intangible assets – net.

The following tables present revenues, Modified EBITDA, significant expenses, and certain segment assets measures:

(1)As Williams is acting as agent for natural gas marketing customers or engages in energy trading activities, the resulting revenues are presented net of the related costs of those activities.

(2)Williams records transactions that qualify as commodity derivatives at fair value with changes in fair value recognized in earnings in the period of change and characterized as unrealized gains or losses. Gains and losses from commodity derivatives held for energy trading purposes are presented on a net basis in revenue.

(3)Segment operating and administrative expenses primarily include payroll, maintenance and operating costs and taxes, and general and administrative expenses, including acquisition and transition-related expenses. It also includes project execution, information technology, finance and accounting, real estate and aviation, central engineering services, safety and operational discipline, supply chain and digital transformation, corporate strategic development, human resources, legal and government affairs, and executive and audit support services costs which are centrally managed and allocated to segments.

(4)Recoverable power, transportation and storage costs are charges incurred which are reimbursable pursuant to FERC stipulations or customer contracts.

(5)Other segment income (expenses) primarily includes equity AFUDC and regulatory credits and charges related to Williams’ regulated operations.

Transco

Transco manages and evaluates its business as a single reportable segment. Transco’s CODM is the Senior Vice President, Transmission & Gulf of America. Transco’s CODM determines resource allocation, measures and evaluates segment operating performance based upon Net income (loss) as reported on the Statement of Net Income.

Significant expenses within net income include Operating and maintenance expenses and Selling, general, and administrative expenses, which are each separately presented on Transco’s Statement of Net Income. Other segment items within net income include natural gas product costs, depreciation and amortization expenses, taxes, other than income taxes, interest expense, interest income, other income (expense) – net, and AFUDC.

Transco’s segment assets include Property, plant, and equipment – net as presented on the Balance Sheet.

NWP

NWP manages and evaluates its business as a single reportable segment. NWP’s CODM is the Senior Vice President, Transmission & Gulf of America. NWP’s CODM determines resource allocation, measures and evaluates segment operating performance based upon Net income (loss) as reported on the Statement of Net Income.

Significant expenses within net income include Operating and maintenance expenses and Selling, general, and administrative expenses, which are each separately presented on NWP’s Statement of Net Income. Other segment items within net income include depreciation and amortization expenses, taxes, other than income taxes, interest expense, other income (expense) – net, and AFUDC.

NWP’s segment assets include Property, plant, and equipment – net as presented on the Balance Sheet.