Vista Energy B de C : Report on Accounting Policies

Mexico City, Mexican United States as of March 11, 2024

REPORT ON THE MAIN ACCOUNTING AND INFORMATION POLICIES AND

CRITERIA OF VISTA ENERGY, S.A.B. DE C.V.

To Ordinary General Assembly of Shares of Vista Energy, S.A.B. de C.V.

Dear Ladies and Gentlemen:

The undersigned, in my character as Chairman of the Board of Directors of Vista Energy, S.A.B. de C.V. ("Company"), in terms of the provisions of the Article 172 b) of the General Law of Commercial Companies, i may submit the report on the main accounting and information policies and criteria followed by the Company in the preparation and presentation of its financial information:

BASIS OF PREPARATION AND PRESENTATION

The financial statements were prepared in accordance with the International Financial Reporting Standards ("IFRS") issued by the International Accounting Standards Board ("IASB"). They were prepared on a historical cost basis, except for certain financial assets and liabilities that were measured at fair value. The figures contained herein are stated in US Dollars ("USD") and are rounded to the nearest thousand, unless otherwise stated. These consolidated financial statements were approved for issuance by the Board on March 11, 2024

• New effective accounting standards, amendments and interpretations issued by the IASB adopted by the Company

• Amendments to IAS 1: Presentation of financial statements - Disclosure of Accounting Policies

In February 2021, the IASB issued amendments to IAS 1, in which it provides guidance and examples to help entities apply materiality judgements to accounting policy disclosures, replacing "significant" with a requirement to disclose their "material" accounting policies.

According to IAS 1, an accounting policy is material if, together with other information contained in the financial statements, it can be expected to influence the decisions made by users of the financial statements.

The amendments to IAS 1 are applicable for annual periods beginning after 1 January 2023.

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The amendments were considered in the preparation of these consolidated financial statements.

• Amendments to IAS 8: Accounting policies, changes in accounting estimates and errors - Definition of accounting estimates

In February 2021, the IASB issued amendments to IAS 8, in which it clarifies the distinction between changes in accounting estimates and changes in accounting policies and the correction of errors. Also, they clarify how entities use measurement techniques and inputs to develop accounting estimates.

The amended standard clarifies that the effects on an accounting estimate of a change in an input or a change in a measurement technique are changes in accounting estimates if they do not result from the correction of prior period errors.

The amendments are effective for annual reporting periods beginning after 1 January 2023.

The amendments had no impact on the Company's consolidated financial statements as the current accounting policies are aligned to the amendments.

• Amendments to IAS 12: Income taxes - Deferred tax related to assets and liabilities arising from a single transaction

On May 7, 2021, the Board issued amendments to IAS 12, related to assets and liabilities arising from a single transaction, that result in the recognition of a simultaneous asset and liability, such as right-of-use assets and lease liabilities or the initial recognition of well plugging and abandonment obligations.

The purpose of such amendments is to limit the application of the exemption from the initial recognition of deferred tax assets and liabilities in certain single transactions.

The amendments are effective for annual reporting periods beginning after 1 January 2023.

The amendments had no impact on the consolidated financial statements.

• Amendments to IAS 12: Income tax. International Tax Reform Pillar Two Model Rules.

On May 23, 2023, the IASB issued amendments to IAS 12 to apply the pillar two model rules published by the Organization for Economic Co-operation and Development ("OECD"), which establish that this model applies to multinational enterprises with revenue in excess of Euros 750 million in their consolidated financial statements.

The IASB amendments are:

1. A mandatory temporary exception to the deferred taxes accounting from the jurisdictional implementation of pillar two income taxes; and

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1. Disclosure requirements for affected entities to help users of the financial information better understand an entity's exposure to Pillar Two income taxes arising from that legislation, particularly before its effective date.

The amendments are effective for annual periods beginning on or after January 1, 2023, immediately and retrospectively, according to the principles established in IAS 8.

The Company is assessing the impact of the amendments on the subsidiaries located in Europe (which have no transactions) since the required regulations have not been issued in the main jurisdictions (Argentina and Mexico) as of the date of these financial statements.

• New accounting standards, amendments and interpretations issued by the IASB not yet effective

• Amendments to IAS 1: Presentation of Financial Statements. Classification of Liabilities as Current or Non-current

In October 2022, the IASB published changes to certain paragraphs of IAS 1 to specify the requirements for classifying liabilities as current or non-current. The amendments clarify:

1. What is meant by a right to defer settlement;
2. That a right to defer must exist at the end of the reporting period;
3. That classification is unaffected by the likelihood that an entity will exercise its deferral right; and
4. That only if an embedded derivative in a convertible liability is itself an equity instrument would the terms of a liability not impact its classification.

These amendments will be effective for annual periods beginning on or after January 1, 2024, and should be applied retrospectively.

These amendments are not expected to have a major impact on the Company's consolidated financial statements.

• Amendments to IAS 7: Statements of Cash Flows, and IFRS 7: Financial Instruments: Disclosures - Disclosure of Supplier Finance Arrangements

On May 25, 2023, the IASB published amendments to IAS 7 and IFRS 7 whereby it introduces new disclosure requirements in IFRS Standards to enhance the transparency and, thus, the usefulness of the information provided by entities about supplier finance arrangement. The new requirements aim to facilitate a better understanding of supplier finance arrangements on an entity's liabilities, cash flows and exposure to liquidity risk.

They will be effective for annual periods beginning on or after January 1, 2024.

These amendments are not expected to have a major impact on the Company's consolidated financial statements.

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• Amendments to IFRS 16: Leases. Recognition of lease liabilities in a sale and leaseback

In September 2022, the IASB published amendments to IFRS 16 related to the recognition of lease liabilities in a sale and leaseback. The amendment specifies the requirements that a seller-lessee should use to measure the lease liability arising in a sale to ensure the seller- lessee does not recognize any amount of the gain or loss that relates to the right of use it retains.

They will be effective for annual periods beginning on or after January 1, 2024. They are applied retrospectively, and early adoption is allowed.

They are not expected to have a major impact on the Company's consolidated financial statements since it has no sale and leaseback transactions.

• Basis of consolidation

The consolidated financial statements comprise the financial statements of the Company and its subsidiaries.

Subsidiaries are all entities over which the Company has control, which occurs if and only if the Company has all the following:

• Power over the entity;
• Exposure or rights to variable returns from its involvement with the entity; and
• The ability uses its power over the entity to affect the amount of the investor's returns.

The Company reassesses whether it controls a subsidiary if facts and circumstances indicate that there are changes to 1 (one) or more of the 3 (three) elements of control mentioned above.

When the Company has less than a majority of the voting rights of an investee, it has power over the latter when the voting rights are sufficient to give it the practical ability to direct the relevant activities of the investee unilaterally.

The Company assesses all facts and circumstances to determine whether voting rights are sufficient to give it power over an entity, including:

• The size of the Company's holding of voting rights relative to the size and dispersion of holdings of the other vote holders;
• potential voting rights held by the Company, other vote holders or other parties;
• rights arising from other contractual arrangements; and
• any additional facts and circumstances that indicate the Company has, or does not have, the current ability to direct the relevant activities at the time that decisions need to be made, including voting patterns at previous shareholders' meeting.

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Relevant activities are those that most significantly affect the subsidiary's performance, such as the ability to approve an operating and capital budget and the power to appoint Management personnel. These decisions show that the Company has rights to direct a subsidiary's relevant activities.

Subsidiaries are consolidated from the date the Company obtains control over them and ceases when such control ends. Specifically, profit and expenses of a subsidiary acquired or disposed of during the year are included in the statements of profit or loss and other comprehensive income as from the date in which the Company obtains control until it assigns or loses such control.

Intercompany transactions, balances and income or losses are deleted. The subsidiaries' financial statements are adjusted when needed to align their accounting policies to the Company's accounting policies

Below are the Company's main subsidiaries:

	Equity interest
			Place of
Subsidiary name	December	December	Main activity
business
	31, 2023	31, 2022
Vista Energy Holding I,	100%	100%	Mexico	Holding company
S.A. de C.V.
Vista Energy Holding II,	100%	100%	Mexico	Exploration and
S.A. de C.V.	production (1)
Vista Energy Holding III,	100%	100%	Mexico	Services
S.A. de C.V.
Vista Energy Holding IV,				Services
S.A. de C.V.	100%	100%	Mexico
Vista Oil & Gas Holding	100%	100%	Netherland	Holding company
V B.V.
Vista Holding VII S.á.r.l.	100%	100%	Luxembourg	Holding company
Vista Energy Argentina	100%	100%	Argentina	Exploration and
S.A.U.	production (1)
Aleph Midstream S.A.	100%	100%	Argentina	Services (2)
Aluvional S.A.	100%	100%	Argentina	Mining and industry
AFBN S.R.L.	100%	100%	Argentina	Exploration and
production (1)
VX Ventures Asociación	100%	100%	Mexico	Holding company
en Participación

1. Its refers to the exploration and production of natural gas and crude oil.
2. Including operations related to the capture, treatment, transport and distribution of hydrocarbons and derivatives.

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Changes in interests:

Changes in the Company's working interests in its subsidiaries that do not result in a change in control of the subsidiary are accounted for as equity transactions. The carrying amount of the Company's interests is adjusted to reflect the changes in interests in the subsidiaries.

When the Company ceases to consolidate or book a subsidiary for loss of control, joint control or significant influence, any retained working interest in the entity is remeasured at fair value with the change in the carrying amount recognized in the statements of profit or loss and other comprehensive income. This fair value becomes the initial carrying amount for the purposes of subsequently booking retained interest as the associate, joint venture or financial asset. In addition, any amount previously recognized in other comprehensive income in relation to such entity is booked as if the Company had directly disposed of the related assets or liabilities. This may mean that the amounts previously recognized in other comprehensive income are reclassified to profit or loss.

If the working interest in a joint venture or associate is reduced, but the entity retains the joint control or significant influence, only a proportion of the previously recognized amounts in other comprehensive income is reclassified to profit or loss.

Joint arrangements:

According to IFRS 11 Joint Arrangements, investments are classified as joint operations or joint venture, depending on contractual rights and obligations. The Company has joint operations but has no joint venture.

Joint operations:

A joint operation is a joint arrangement whereby the parties that have joint control of the arrangement have rights to the assets, and obligations for the liabilities, relating to the arrangement. Joint control exists only when decisions about the relevant business activities require the unanimous consent of the parties that collectively control the arrangement.

When the Company carries out activities under joint operations, the Company as a joint operator, to recognize in proportion to its interest in the joint arrangement:

• Its assets and liabilities held jointly;
• Its revenue from the sale of its share of the output of the joint operation;
• Its revenue from the sale of its share of the output of the joint operation; and
• Its expenses, including its share of any expenses incurred jointly.

The Company books its assets, liabilities, revenues and expenses related to its interest in a joint operation according to the IFRS applicable to specific assets, liabilities, revenues and expenses. They were included in the consolidated financial statements in the related accounts. Interest in joint operations were based on the latest financial statements or financial information available as of every year-end considering significant subsequent events and transactions, and management information available. The financial statements

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or the financial information of the joint operations are adjusted, if needed, so that the accounting policies are consistent with the Company's accounting policies.

• Summary of material accounting policies:
  (1) Segment information

The operating segments are reported in a consistent manner with the internal reports provided by the Executive Management Committee (the "Committee" that is considerate the "Chief Operating Decision Maker" or "CODM").

The CODM is the highest decision-making authority, in charge of allocating resources and establishing the performance of the entity's operating segments and was identified as the body executing the Company's strategic decisions.

1. Property, plant and equipment, and intangible assets Property, plant and equipment

Property, plant and equipment is measured using the cost model, the asset is valued at cost less depreciation and any subsequent accumulated impairment loss.

Subsequent costs are included in the carrying amount of the asset or are recognized as a separate asset, as the case may be, only when it is probable that future economic benefits may flow to the Company and the cost of the asset may be measured reliably, otherwise such costs are charged to profit or loss during the reporting period in which they are incurred.

Works in progress are booked at cost less any impairment loss, of applicable.

Profit and loss from the sale of property, plant and equipment is calculated by comparing the consideration received with the carrying amount of the date in which the transaction was carried out.

Depreciation methods and useful lives:

Estimated useful lives, residual values and the depreciation method are reviewed at every period-end, and changes are recognized prospectively. An asset is impaired when it carrying amount exceeds its recoverable amount.

The Company amortizes drilling costs applicable to productive and in development, productive wells and production facilities, according to the unit of production method ("UDP" by Spanish acronym), applying the proportion of Crude oil and Natural gas produced to prove and develop Crude oil and Natural gas reserves, as the case may be. The mineral properties is amortized applying the proportion of produced Crude oil and Natural gas to total estimated Crude oil and Natural gas proved reserves.

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The costs of acquiring properties with unproved reserves are valued at cost, and their recoverability is assessed regularly based on geological and engineering estimates of the reserves and resources expected to be proved during the life of each concession and are not depreciated.

Capitalized costs related to the acquisition of properties and the extension of concessions with proved reserves were depreciated per field based on a UDP by applying the proportion of produced Crude oil and Natural gas to estimated total proved oil and gas reserves.

The Company's remainder items of property, plant and equipment (including significant identifiable components) are depreciated using the straight-line method based on their estimated useful lives, as detailed below: 50 years for the buildings; 10 years for machinery and installations; 10 years for the equipment and furniture; 5 years for the vehicles; and 3 years for the computer equipment.

Land does not depreciate.

Assets for oil and gas exploration:

The Company adopts the successful effort method to account for its oil and gas exploration and production activities.

This method implies the capitalization of: (i) the cost of acquiring properties in oil and gas exploration and production areas; (ii) the cost of drilling and equipping exploration wells arising from the discovery of commercially recoverable reserves; (iii) the cost of drilling and equipping development wells; and (iv) estimated well plugging and abandonment obligations.

Exploration and evaluation involve the search for hydrocarbon resources, the assessment of its technical viability and the assessment of the commercial feasibility of an identified resource.

According to the successful effort method, exploration costs such as geological and geophysical ("G&G") costs, excluding the costs of exploration wells and 3D seismic testing in operating concessions, are expensed in the period in which they are incurred.

These capitalized costs are subject to technical, commercial and administrative review, and a review of impairment indicators at least once a year. When there is sufficient management information indicating impairment.

Estimated well plugging and abandonment obligations in hydrocarbon areas, discounted at a risk-adjusted rate, are capitalized in the cost of assets and are amortized using the UDP method. A liability for the estimated value of discounted amounts payable is also recognized. Changes in the measurement of these obligations as a consequence of changes in the estimated term, the cost or discount rate are added to or deducted from the cost of the related asset.

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Rights and Concessions:

Rights and concessions are booked as part of property, plant and equipment and are depleted on the UDP over the total proved developed and undeveloped reserves of the relevant area. The calculation of the UDP rate for the depreciation / amortization of development costs considers expenses incurred to date and authorized future development expenses.

Intangible assets

Goodwill:

Goodwill arises during a business combination and represents the excess of the consideration transferred over the fair value of net assets acquired. After initial recognition, goodwill is measured at cost less cumulative impairment losses.

To conduct impairment tests, goodwill is allocated as from acquisition date to each cash- generating unit ("CGU"), which represents the lowest level within the Company at which the goodwill is monitored for internal management purposes. Goodwill is tested once a year.

When goodwill is allocated to a CGU and part of the transaction within such unit is eliminated, goodwill related to such eliminated transaction is included in the carrying amount of the transaction to determine gain or loss on sale.

Other intangible assets:

Other intangible assets acquired separately are measured using the cost model; after initial recognition, the asset is valued at cost less amortization and any subsequent accumulated impairment loss.

Intangible assets are amortized using the straight-line method; software licenses are amortized over their estimated 3 (three) year useful life. The amortization of these assets is recognized in the statements of profit or loss and other comprehensive income.

The estimated useful life, residual value and amortization method are reviewed at every period-end, and changes are recognized prospectively. An asset is impaired when it carrying amount exceeds its recoverable amount.

(3) Leases

The Company has lease contracts for various items of buildings, facilities and machinery, which are recognizes under IFRS 16.

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The Company recognizes right-of-use assets at the commencement date of the lease (i.e., on the date when the underlying asset is available for use). Right-of-use assets are measured at cost, net of the accumulated depreciation and impairment losses, and are adjusted by the remeasurement of lease liabilities. The cost of assets includes the amount for recognized liabilities, direct costs initially incurred, and payments made until the commencement date. Unless the Company is reasonably certain that it will obtain the ownership of the leased asset at the end of the contract, these assets are depreciated under the straight-line method during the shortest of its estimated useful life and the lease term. Right-of-use assets are subject to impairment.

The Company recognizes lease liabilities measured at the present value of the payments to be made during the lease term. These payments include fixed payments, variable payments dependent on an index or rate, and the purchase option and the penalty payments from lease termination. The Company determines the lease term as the noncancellable lease term, together with any period covered by an option to extend the agreement if it is reasonably certain that it will exercise that option. To calculate the present value of lease payments, the Company uses the incremental borrowing rate at the lease contract.

After the commencement date, liabilities will be increased to reflect the accretion of interest and will be reduced by the payments made. In addition, the carrying amount of lease liabilities are remeasured if there is an amendment, a change in the lease term, a change in the fixed or in-substance fixed payments or a change in the assessment to buy the underlying asset.

The Company applies the exemption to recognize short-term leases (i.e., those leases for a term under 12 (twelve) months as from the commencement date with no call option). Also, the low-value asset exemption also applies to low-value items. The lease payments of low- value assets are recognized as expenses under the straight-line method during the lease term.

(4) Impairment of nonfinancial assets other than goodwill

Other nonfinancial assets with a definite useful life undergo impairment tests whenever events or changes in circumstances have indicated that their carrying value may not be recoverable. When the carrying amount of the asset exceeds its recoverable amount, an impairment loss is recognized for the value of the asset. An asset's recoverable amount is the higher of (i) the fair value of an asset less costs of disposal and (ii) its value in use.

Assets are tested for impairment at the lowest level in which there are separately identifiable cash flows largely independent of the cash flows of other groups of assets or CGUs. Amortized nonfinancial assets are reviewed for potential reversal of impairment at the end of each reporting period.

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