References to the combined financial statements of the Centessa Predecessor Group refer to three of the eleven direct acquired Centessa Subsidiaries that were deemed to represent the predecessor entity prior to the Company’s acquisition of the Centessa Subsidiaries in January 2021. The Centessa Predecessor Group includes the combined financial information of Z Factor, Morphogen-IX and LockBody. The successor includes the consolidated financial information of Centessa and all Centessa subsidiaries subsequent to the acquisition.

Accordingly, the accompanying consolidated and combined financial statements are presented in accordance with Securities and Exchange Commission (“SEC”) requirements for predecessor and successor financial statements, which include the financial results of both the Company and the Centessa Predecessor Group. The consolidated balance sheets present the consolidated financial position of the Company as of December 31, 2022 and December 31, 2021. The results of operations and cash flows contained in the consolidated and combined financial statements include the Company’s consolidated financial results and cash flows for the twelve months ended December 31, 2022 and for the period from January 30, 2021 through December 31, 2021; and the Centessa Predecessor Group’s combined financial results and cash flows for the period from January 1, 2021 through January 29, 2021.

The accompanying consolidated and combined financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and

We are an “emerging growth company,” as defined in the Jumpstart Our Business Startups Act (“JOBS Act”) enacted in April 2012. For so long as we remain an emerging growth company, we are permitted and intend to rely on certain exemptions from various public company reporting requirements, including not being required to have our internal control over financial reporting audited by our independent registered public accounting firm pursuant to Section 404(b) of the Sarbanes-Oxley Act of 2002, reduced disclosure obligations regarding executive compensation in our periodic reports and proxy statements, exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and any golden parachute payments not previously approved.

We will remain an emerging growth company until the earlier to occur of (1) the last day of the fiscal year that is five years following the closing of our initial public offering, (2) the last day of the fiscal year in which we have total annual gross revenues of at least $1.235 billion, (3) the last day of the fiscal year in which we are deemed to be a “large accelerated filer,” under the rules of the U.S. Securities and Exchange Commission, or SEC, which means the market value of our equity securities that is held by non-affiliates exceeds $700 million as of the prior June 30th after we have been subject to the SEC’s periodic reporting requirements for at least twelve calendar months and have filed at least one annual report, and (4) the date on which we have issued more than $1.0 billion in non-convertible debt during the prior three-year period.

In addition, the JOBS Act provides that an emerging growth company can take advantage of an extended transition period for complying with new or revised accounting standards. This provision allows an emerging growth company to delay the adoption of some accounting standards until those standards would otherwise apply to private companies. We are electing to utilize the extended transition period and, as a result, will comply with new or revised accounting standards on the relevant dates on which adoption of such standards is required for emerging growth companies.

We are also a “smaller reporting company” as defined in the Securities Exchange Act of 1934 (the “Exchange Act”). Even after we no longer qualify as an emerging growth company, we may still qualify as a “smaller reporting company” if the market value of our ordinary shares held by non-affiliates is below $250 million (or $560 million if our annual revenue is less than $100 million) as of June 30 in any given year. As a smaller reporting company, we are eligible for scaled disclosure relief from certain Regulation S-X and Regulation S-K requirements. The Company adopted the scaled disclosures in this annual report on Form 10-K.

The Company’s financial statements are presented in U.S. dollars (“USD”), the reporting currency of the Company. The functional currency of Centessa Pharmaceuticals plc is USD and the functional currency of the Centessa Subsidiaries is their respective local currency. Income and expenses have been translated into USD at average monthly exchange rates prevailing during the period. Assets and liabilities have been translated at the rates of exchange on the balance sheets dates and equity accounts at their respective historical rates. The resulting translation gain and loss adjustments are recorded directly as a separate component of shareholders’ equity as other comprehensive (loss) income. Transactions denominated in a currency other than the functional currency are remeasured based upon the exchange rate at the date of remeasurement with the resulting gain or loss included in the accompanying consolidated and combined statements of operations and comprehensive loss within Other income (expense), net. The aggregate foreign currency transaction loss included in the Company (Successor)’s results of operations for the twelve months ended December 31, 2022 and for the period from January 30, 2021 through December 31, 2021 were $2.8 million and $3.6 million, respectively.

The functional currency of Centessa Pharmaceuticals plc had previously been British pounds (“GBP”), as Centessa Pharmaceutical plc’s primary activities during formation were mostly denominated in GBP, including related transaction costs, the acquisition of Centessa subsidiaries predominantly with operations in GBP and the issuance of shares with a GBP nominal value as consideration in the acquisition. Beginning in the second quarter of 2021, the functional currency of Centessa Pharmaceuticals plc changed from GBP to USD. The change in functional currency was the result of many factors including the completion of an IPO and receipt of proceeds in USD which resulted in USD denominated assets exceeding GBP denominated assets, the increase in the number of U.S.-based employees, and the increase in costs denominated in USD, following completion of the Company’s IPO on a U.S. stock exchange (“Nasdaq”). Given these significant changes, the Company considered the economic factors outlined in ASC 830, Foreign Currency Matters and concluded that the majority of the factors supported the use of the USD as the functional currency for Centessa Pharmaceutical plc.

The change in functional currency for Centessa Pharmaceuticals plc was applied on a prospective basis beginning in the second quarter of 2021 and translation adjustments for prior periods will continue to remain as a component of accumulated other comprehensive loss. The Company reclassified the presentation of foreign currency gains and losses recognized in the first quarter of 2021 from General & administration expense to Other income (expense), net to conform to the current period financial statement presentation.

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated and combined financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates.

Estimates and assumptions are periodically reviewed and the effects of revisions are reflected in the consolidated and combined financial statements in the period they are determined to be necessary. Significant areas that require management’s estimates include accrued research and development expenses, the note purchase agreement, share-based compensation, contingent value rights, and, prior to the IPO, the fair value of the Company’s ordinary shares.

Property and equipment are recorded at cost and depreciated using the straight-line method over the estimated useful lives of the respective assets. Property and equipment includes computer equipment, which has a useful life of three years, as well as leasehold improvements under construction, which have useful lives of the lesser of applicable lease terms or their useful lives. The costs of maintenance and repairs are expensed as incurred. Improvements and betterment that add new functionality or extend the useful life of the asset are capitalized. Depreciation expense for the twelve months ended December 31, 2022 and for the period from January 30, 2021 through December 31, 2021 was $131 thousand and $34 thousand, respectively.

Capitalized software as a service costs representing costs incurred during the application development stage are included in “Other non-current assets” and the corresponding current portion, in “Prepaid expenses and other current assets” and is amortized using the straight line method over five years. Costs incurred during the preliminary project stage and the post-implementation-operation stage are expensed as incurred. Hosting fees associated with the hosting as a service arrangement are expensed on a straight line basis over the term of the hosting arrangement.

Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated undiscounted future cash flows, then an impairment charge is recognized for the amount by which the carrying value of the asset exceeds the estimated fair value of the asset. As of December 31, 2022, the Company believes that no revision of the remaining useful lives or write-down of long-lived assets is required.

Fair value is the price that could be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value determination in accordance with applicable accounting guidance requires that a number of significant judgments be made. Additionally, fair value is used on a nonrecurring basis to evaluate assets for impairment or as required for disclosure purposes by applicable accounting guidance on disclosures about fair value of financial instruments. Depending on the nature of the assets and liabilities, various valuation techniques and assumptions are used when estimating fair value. The carrying amounts of certain of the Company’s financial instruments, including cash and cash equivalents, prepaid expense and accounts payable, are shown at cost, which approximates fair value due to the short-term nature of these instruments. The Company follows the provisions of FASB ASC Topic 820, Fair Value Measurement, for financial assets and liabilities measured on a recurring basis. The guidance requires fair value measurements be classified and disclosed in one of the following three categories:

As described in further detail in Note 6 - "Debt", in October 2021, the Company entered into a Note Purchase Agreement (the “Notes”) with Oberland Capital Management LLC (“Oberland Capital”). Under the terms of the agreement, Oberland Capital will purchase up to $300.0 million of 6-year, interest-only (initial interest rate was 8.0% per annum), senior secured notes (the Notes) from the Company including $75.0 million, funded on October 4, 2021, $125.0 million available through 2023 at the Company’s option, and $100.0 million available to fund Mergers and Acquisitions (M&A), in-licensing, or other strategic transactions, at the option of the Company and Oberland Capital. In addition, the Company is obligated to pay a Milestone payment equal to 30% of the aggregate principal amount issued under the Notes by the Company upon regulatory approval of any drug candidate.

The Company evaluated the Notes and determined that the Notes include embedded derivatives that would otherwise require bifurcation as derivative liabilities. Neither the debt instrument nor any embedded features are required to be classified as equity. Therefore, the hybrid financial instrument comprised of the debt host and the embedded derivative liability may be accounted for under the fair value option. The Company elected to carry the Notes at fair value, and the debt instrument is outside the scope of ASC 480, Distinguishing Liabilities from Equity, and thus will be classified as a liability under ASC 470, Debt, in the Company’s financial statements. As the Company has elected to account for the Notes under the fair value option, debt issuance costs were immediately expensed.

The fair value of the Note Purchase Agreement represents the present value of estimated future payments, including interest, principal as well as estimated payments that are contingent upon the achievement of specified milestones. The fair value of the Notes is based on the cumulative probability of the various estimated payments. The fair value measurement is based on significant Level 3 unobservable inputs such as the probability of achieving the milestones, anticipated timelines, probability and timing of an early redemption of all obligations under the agreement and the discount rate. Any changes in the fair value of the liability in each reporting period are recognized in the consolidated statement of operations and comprehensive loss until it is settled.

All research and development costs are expensed in the period incurred and consist primarily of salaries, payroll taxes, employee benefits, stock-based compensation charges for those individuals involved in research and development efforts, external research and development costs incurred under agreements with contract research organizations and consultants to conduct and support the Company’s ongoing clinical trials.

The Company has entered into various research and development contracts with clinical research organizations, clinical manufacturing organizations and other companies. Payments for these activities are based on the terms of the individual agreements, which may differ from the pattern of costs incurred. Payments made in advance of performance are reflected in the accompanying balance sheets as prepaid expenses, while payments made after performance are reflected as accrued liabilities in the accompanying balance sheets. The Company records accruals for estimated costs incurred for ongoing research and development activities. When recording accruals for ongoing research and development activities, the Company analyzes progress of the services, including the phase or completion of events, invoices received and contracted costs. Nonrefundable advance payments for goods and services, including fees for process development or manufacturing and distribution of clinical supplies that will be used in future research and development activities, are recognized as expense in the period that the related goods are consumed or services are performed.

Milestone payments within the Company (Successor)’s licensing arrangements are recognized when achievement of the milestone is deemed probable to occur. To the extent products are commercialized and future economic benefit has been established, commercial milestones that become probable are capitalized and amortized over the estimated remaining useful life of the intellectual property. Significant judgments and estimates may be made in determining the prepaid or accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates.

The Company participates in research tax incentive programs that are granted to companies by the United Kingdom and certain European tax authorities in order to encourage them to conduct technical and scientific research. Expenditures that meet the required criteria are eligible to receive a tax credit that is reimbursed in cash. Estimates of the amount of the cash refund expected to be received are determined at each reporting period and recorded as reductions to research and development expenses. The Company recorded research and development tax incentives of $12.6 million and $13.8 million during the twelve months ended December 31, 2022 and the period from January 30, 2021 through December 31, 2021, respectively.

The Company may not be able to continue to claim the most beneficial payable research and development tax credits in the future if it ceased to qualify as a small or medium enterprise, based on size criteria concerning employee headcount, turnover and gross assets. In addition, unless its subsidiaries qualify for an exemption, there are limitations to how much tax incentive can be claimed. This limitation is calculated as the total of the Company's relevant expenditure on employees in the period, multiplied by 300%, plus £20,000.

On January 1, 2022, the Company adopted ASU No. 2016-02, Leases (“ASC 842”), which requires a lessee to record a right-of-use asset and a corresponding lease liability on the balance sheet for all leases with terms longer than 12 months. As of January 1, 2022, the Company was not party to any significant leases and therefore the adoption of this standard did not have a significant impact as of this adoption date. As permitted in the standards, the Company is reflecting the adoption of ASC 842 in its annual report on Form 10-K for the year ended December 31, 2022, and in interim periods within the fiscal year ended December 31, 2023.

In accordance with ASC 842, the Company assesses whether an arrangement is a lease, or contains a lease at the inception of the arrangement. When an arrangement contains a lease, the Company categorizes leases with contractual terms longer than twelve months as either operating or finance. Finance leases are generally those leases that allow us to substantially utilize or pay for the entire asset over its estimated life. Assets acquired under finance leases are recorded in “Property and equipment, net.” All other leases are categorized as operating leases.

The Company records right-of use ("ROU") assets and lease obligations for its finance and operating leases, which are initially recognized based on the discounted future lease payments over the term of the lease. As the rate implicit in the Company's leases may not be easily determinable, the Company uses its incremental borrowing rate to calculate the present value of the sum of the lease payments. Lease terms may include options to extend or terminate the lease. The Company will include such options in determining the lease term when it is reasonably certain that the Company will exercise such options. Operating and finance lease ROU assets are recognized net of any lease prepayments and incentives. The Company elected the practical expedient to not separate lease and non-lease components and, accordingly, accounts for them as a single component. Operating lease expense is recognized on a straight-line basis over the lease term. Finance lease expense is recognized based on the effective-interest method over the lease term. The Company elected not to recognize ROU assets and lease obligations for any short-term leases, which are defined as leases with an initial term of 12 months or less.

On February 7, 2022, the Company entered into a 10-year office lease (the “Boston Lease”) for its new corporate headquarters in Boston, Massachusetts. The Boston Lease contains 18,922 square feet with a fixed annual rent of approximately $1.6 million in 2023, escalating to approximately $1.9 million by Year 10. The Company may, at its discretion, extend the Boston Lease for one extension term of five years. The Company will recognize an operating lease right-of-use asset and lease liability for this facility upon lease commencement, expected in early 2023 after the construction of the leased space. The Company intends to sublet a portion of the Boston Lease after the commencement of the lease.

The Company enters into collaborative arrangements to develop and commercialize intellectual property. These arrangements typically involve two (or more) parties who are active participants in the collaboration and are exposed to significant risks and rewards dependent on the commercial success of the activities. These collaborations usually involve various activities by one or more parties, including research and development, marketing and selling and distribution. Often, these collaborations require upfront, milestone and royalty or profit share payments, contingent upon the occurrence of certain future events linked to the success of the asset in development. Amounts due to collaborative partners related to development activities are generally reflected as research and development expense.

The Company uses the Black-Scholes option pricing model to value its stock option awards. The expected life of the stock options is estimated using the “simplified method,” as the Company has limited historical information from which to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock option grants. The simplified method is the midpoint between the vesting period and the contractual term of the option. For share price volatility, the Company uses comparable public companies as a basis for its expected volatility to calculate the fair value of option grants. The risk-free rate is based on the U.S. Treasury yield curve commensurate with the expected life of the option. The estimated annual dividend yield is 0% because the Company has not historically paid and does not expect for the foreseeable future to pay a dividend on its ordinary shares.

Prior to its IPO in June 2021, the fair value of the Company’s ordinary shares was determined by the Company’s board of directors with assistance from management and an independent third-party valuation firm. As discussed in further detail in Note 3 - "Acquisitions and Dispositions", the estimated fair value of its ordinary shares was based on the Hybrid Method outlined in the American Institute of Certified Public Accountants’ Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation, (“Practice Guide”). Subjective factors considered by the Company’s board of directors and management included the addition of new executive members and the election of new independent directors to the Company’s board of directors, as well as definitive plans to undertake an IPO. The assumptions used in estimating the fair value of share-based awards represented management’s estimate and involved inherent uncertainties and the application of management’s judgment. As a result, if factors changed and management used different assumptions, share-based compensation expense would have been materially different.

The Company provided defined contribution plans to its employees beginning in 2021 and continuing in 2022. In the US, the primary plan sponsored by the Company is a safe harbor, 401k plan with a 4% employer match, no waiting period and immediate vesting on the match. In the UK, the primary plan sponsored by the Company is a money purchase plan, which requires a minimum 8% contribution, including a minimum employer contribution of 4% and employee contribution of 4% in 2022. The Company recorded charges of $0.7 million and $0.2 million under these plans during the twelve months ended December 31, 2022 and the period from January 30, 2021 through December 31, 2021, respectively.

The Company follows the asset and liability method of accounting for income taxes under ASC 740, Income Taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statements carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that included the enactment date. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized.

ASC 740 prescribes a recognition threshold and a measurement attribute for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities. The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. There were no unrecognized tax benefits and no amounts accrued for interest and penalties as of December 31, 2022 and December 31, 2021. The Company is currently not aware of any issues under review that could result in significant payments, accruals or material deviation from its position. The Company is subject to income tax examinations by major taxing authorities since inception.

Basic loss per ordinary share is computed by dividing net loss by the aggregate weighted-average number of ordinary shares outstanding. Diluted loss per ordinary share includes the effect, if any, from the potential exercise or conversion of securities, such as convertible preferred shares, stock options, unvested restricted ordinary shares and

convertible debt which would result in the issuance of incremental ordinary shares. For diluted net loss per ordinary share, the weighted-average number of ordinary shares is the same for basic net loss per ordinary share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive.

In March 2022, the FASB issued ASU No 2022-01, Derivatives and Hedging (Topic 815): Fair Value Hedging-Portfolio Layer Method. The amendments in this Update expand the current last-of-layer method of hedge accounting that permits only one hedged layer to allow multiple hedged layers of a single closed portfolio. To reflect that expansion, the last-of-layer method is renamed the portfolio layer method. This ASU is the final version of Proposed Accounting Standards Update 2021-002-Derivatives and Hedging (Topic 815): Fair Value Hedging-Portfolio Layer Method, which has been deleted. The amendments in this Update apply to all entities that elect to apply the portfolio layer method of hedge accounting in accordance with Topic 815. For public business entities, the amendments in this Update are effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. For all other entities, the amendments are effective for fiscal years beginning after December 15, 2023, and interim periods within those fiscal years. Early adoption is permitted on any date on or after the issuance of this Update for any entity that has adopted the amendments in Update 2017-12 for the corresponding period. We do not have any hedging instruments that would be subject to this guidance. Therefore, we do not expect any related impact on the Company's consolidated financial statements and related disclosures.

In June 2022, the FASB issued ASU No 2022-03, Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions. The amendments in this Update affect all entities that have investments in equity securities measured at fair value that are subject to a contractual sale restriction. The amendments clarify that a contractual restriction on the sale of an equity security is not considered part of the unit of account of the equity security and, therefore, is not considered in measuring fair value. The amendments also clarify that an entity cannot, as a separate unit of account, recognize and measure a contractual sale restriction. This Accounting Standards Update is the final version of Proposed Accounting Standards Update 2021-005-Fair Value (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions, which has been deleted. For public business entities, the amendments in this Update are effective for fiscal years beginning after December 15, 2023, and interim periods within those fiscal years. For all other entities, the amendments are effective for fiscal years beginning after December 15, 2024, and interim periods within those fiscal years. Early adoption is permitted for both interim and annual financial statements that have not yet been issued or made available for issuance. We do not have any equity securities subject to contractual sale restrictions that would be subject to this guidance. Therefore, we do not expect any related impact on the Company's consolidated and combined financial statements and related disclosures.

In September 2022, the FASB issued ASU No 2022-04, Liabilities-Supplier Finance Programs (Subtopic 405-50): Disclosure of Supplier Finance Program Obligations. Subtopic 405-50 requires that a buyer in a supplier finance program disclose sufficient information about the program to allow a user of financial statements to understand the program’s nature, activity during the period, changes from period to period, and potential magnitude. The amendments in this Update require qualitative and quantitative disclosures about supplier finance programs and thereby allow financial statement users to better understand the effect of those programs on an entity’s working capital, liquidity, and cash flows. This Accounting Standard Update applies to all entities that use supplier finance programs in connection with the purchase of goods and services. This Accounting Standards Update is the final version of Proposed Accounting Standards Update 2021-007-