Quarterly Report for Quarter Ending March 31, 2026 (Form 10-Q)

Management's Discussion and Analysis of Financial Condition and Results of Operations.

The following discussion and analysis of our financial condition and results of operations should be read in conjunction with our unaudited condensed financial statements and related notes appearing elsewhere in this Quarterly Report on Form 10-Q and our audited financial statements and related notes for the year ended December 31, 2025 included in our Annual Report on Form 10-K filed with the Securities and Exchange Commission on February 24, 2026, as amended by Amendment No. 1 thereto filed with the Securities and Exchange Commission on April 28, 2026, which we refer to as the 2025 Annual Report on Form 10-K.

This Quarterly Report on Form 10-Q contains forward-looking statements that involve substantial risks and uncertainties. All statements, other than statements of historical facts, contained in this Quarterly Report on Form 10-Q, including statements regarding our strategy, future operations, future financial position, future revenue, projected costs, prospects, plans and objectives of management and expected market growth are forward-looking statements. The words "anticipate," "believe," "continue," "could," "estimate," "expect," "intend," "may," "plan," "potential," "predict," "project," "should," "target," "would" and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.

We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make. Please also refer to those factors described in "Part I, Item 1A. Risk Factors" of our 2025 Annual Report on Form 10-K for important factors that we believe could cause actual results to differ materially from those in our forward-looking statements.

Proposed Acquisition by Biogen Inc.

On March 31, 2026, we entered into an Agreement and Plan of Merger, or the Merger Agreement with Biogen Inc., a Delaware corporation, or Parent, and Aspen Purchaser Sub, Inc., a Delaware corporation and a direct wholly owned subsidiary of Parent, or Purchaser.

Pursuant to the Merger Agreement, and upon the terms and subject to the conditions therein, Purchaser will commence a tender offer, or the Offer, to acquire any and all of our issued and outstanding shares of our common stock in exchange for (i) $41.00 per share of our common stock, net to the seller in cash, without interest and subject to reduction for any applicable tax withholding (such amount, or any higher amount per share paid pursuant to the Offer, the Upfront Consideration), plus (ii) one contractual, non-transferable contingent value right, or CVR, per share of common stock which shall entitle the holder to receive potential payments of up to an aggregate of $4.00 in cash, without interest and subject to reduction for any applicable tax withholding, upon the achievement of certain specified milestones described below in accordance with the terms and conditions of a contingent value rights agreement to be entered into with a rights agent mutually acceptable to Parent and us (the Upfront Consideration plus one CVR, together, the Offer Price). The Offer will remain open for 20 business days, subject to extension under certain circumstances. On April 14, 2026, Purchaser commenced the Offer with the filing of the Schedule TO with the Securities and Exchange Commission, or the SEC, and we filed the Schedule 14D-9 with the SEC.

Promptly following the consummation of the Offer, subject to the terms and conditions set forth in the Merger Agreement, and in accordance with the General Corporation Law of the State of Delaware, or the DGCL, Purchaser will merge with and into us, with us continuing as the surviving corporation and a wholly owned subsidiary of Parent, or the Merger. The Merger Agreement contemplates that the Merger will be effected pursuant to Section 251(h) of the DGCL, with no stockholder vote required to consummate the Merger. At the effective time of the Merger, or the Effective Time, each share of common stock (other than shares of common stock that are (i) held in our treasury, (ii) irrevocably accepted for purchase in the Offer by Purchaser and "received" (as such term is defined by Section 251(h)(6)(f) of the DGCL) by Purchaser, (iii) held by Parent, Purchaser or any other wholly owned subsidiary of the Parent as of both the commencement of the Offer and immediately prior to the Effective Time and (iv) held by stockholders who are entitled to, and properly demand, appraisal for such shares of common stock in accordance with Section 262 of the DGCL) will be cancelled and converted into the right to receive the Offer Price from Purchaser without interest, subject to reduction for any applicable withholding taxes.

The Merger Agreement is subject to certain closing conditions and is expected to close in the middle of the second quarter of 2026.

Overview

We are a commercial-stage biopharmaceutical company focused on the discovery, development and commercialization of novel therapeutic compounds to treat diseases with high unmet needs through the inhibition of the complement system, which is an integral component of the immune system. We believe this approach has the potential to effectively control diseases with high unmet need that

are driven by excessive complement activation. We currently have two marketed drugs that target C3, the central protein in the complement cascade: SYFOVRE (pegcetacoplan injection), approved by the U.S. Food and Drug Administration, or FDA, in February 2023 for the treatment of geographic atrophy secondary to age-related macular degeneration, or GA; and EMPAVELI (pegcetacoplan), approved by the FDA in May 2021 for the treatment of paroxysmal nocturnal hemoglobinuria, or PNH, and approved by the FDA in July 2025 for the treatment of C3 glomerulopathy, or C3G, and primary immune complex membranoproliferative glomerulonephritis, or primary IC-MPGN.

We believe SYFOVRE has the potential to be the standard of care for patients with GA, a disease that affects an estimated 1.5 million people in the United States. While we have exclusive, worldwide commercialization rights for intravitreal pegcetacoplan, we intend to focus our commercialization efforts in the U.S. and explore international expansion in select markets, including Australia, where we received marketing approval in January 2025. We launched SYFOVRE in the United States in March 2023. For the three months ended March 31, 2026 and 2025, we generated $150.7 million and $130.2 million, respectively, in U.S. net product revenue from sales of SYFOVRE. We are developing a next-generation therapy by combining SYFOVRE treatment with APL-3007, which is a small interfering RNA, or siRNA, aimed at comprehensively blocking complement activity in the retina and the choroid. We initiated a Phase 2 multi-dose clinical trial of this combination in patients with GA in June 2025.

We believe that EMPAVELI has the potential to be a best-in-class treatment for a range of indications with high unmet needs. We have exclusive U.S. commercialization rights for EMPAVELI, and our collaboration partner, Swedish Orphan Biovitrum AB (Publ), or Sobi, has exclusive ex-U.S. commercialization rights for systemic pegcetacoplan outside of the United States. For the three months ended March 31, 2026 and 2025, we generated $41.3 million and $19.7 million, respectively, in U.S. net product revenue from sales of EMPAVELI and received $0.8 million and $6.1 million, respectively, in royalties from Sobi.

We initiated two pivotal clinical trials with EMPAVELI in the fourth quarter of 2025, one for the treatment of primary focal segmental glomerulosclerosis, or FSGS, and one for delayed graft function, or DGF. FSGS and DGF are both rare, severe nephrology conditions in which complement overactivation plays a significant role.

On July 1, 2025, we entered into a Royalty Buy-Down Agreement, or the Royalty Agreement, with our collaboration partner, Sobi, under which Sobi paid us an upfront payment of $275.0 million, and agreed to pay up to an aggregate of $25.0 million upon the European Medicines Agency, or EMA, approval of Aspaveli for C3G and primary IC-MPGN, and we agreed to reduce Sobi's royalty payment obligations under our Collaboration and License Agreement with Sobi, or the Sobi Collaboration Agreement, by 90%, subject to defined caps tied to Aspaveli's performance, including an initial cap of 1.45x of the amounts paid by Sobi to us under the Royalty Agreement. If a cap is met, Sobi's royalty payment obligations under the Sobi Collaboration Agreement will revert to 100%.

In January 2026, Sobi received EMA approval of Aspaveli for C3G and primary IC-MPGN. Sobi paid us an additional $25.0 million in February 2026 pursuant to the Royalty Agreement and an additional $30.0 million regulatory development milestone in April 2026 pursuant to the Sobi Collaboration Agreement. This $55.0 million is recorded as licensing and other revenue on our consolidated statement of operations and comprehensive income/(loss) in the first quarter of 2026.

Finally, we are developing new product candidates to further advance our pipeline. Through our collaboration with Beam Therapeutics, Inc., or Beam, we have commenced preclinical studies for APL-9099, a treatment targeting the neonatal Fc receptor, or FcRn, which has the potential to be a first-in-class gene editing treatment for future target indications with one-time dosing. We are also developing other programs with our proprietary in-house capabilities and under our Beam collaboration.

To date, we have financed our operations primarily through $2.6 billion in net proceeds from public offerings of our common

stock and pre-funded warrants to purchase common stock, $745.5 million in payments under our Sobi Royalty and Collaboration Agreements, $532.5 million under various credit arrangements, including with Sixth Street Lending Partners, or Sixth Street, and SFJ Pharmaceuticals Group, or SFJ, and $98.8 million relating to the unwinding of certain capped call transactions in March 2024, as well as from the proceeds of our operations. To date, we have exchanged $425.4 million and converted $0.7 million of aggregate principal amount of our Convertible Notes for shares of our common stock.

Excluding the revenue generated from the Royalty Agreement with Sobi for the year ended December 31, 2025 and the three months ended March 31, 2026, we have incurred significant net operating losses in each year since inception and, while we anticipate achieving net operating income based on our current operating plan, we may not sustain profitability and could incur losses in the future. Our net income was $18.7 million and our net loss was $92.2 million for the three months ended March 31, 2026 and 2025, respectively. As of March 31, 2026, we had an accumulated deficit of $3.0 billion.

Our operating results may fluctuate significantly from quarter to quarter and year to year. We anticipate that we will continue to incur significant commercialization expenses related to sales, marketing, medical affairs, manufacturing, distribution and other commercial infrastructure associated with the commercialization of EMPAVELI for PNH, C3G and primary IC-MPGN and the commercialization of SYFOVRE for the treatment of GA. In addition, we expect to continue to incur significant expenses if and as we continue to

develop and conduct our ongoing and planned clinical trials of systemic pegcetacoplan and our other product candidates; initiate and continue research and preclinical and clinical development efforts for any future product candidates; seek to identify and develop additional product candidates for complement-dependent diseases; seek regulatory and marketing approvals for our product candidates that successfully complete clinical trials, if any; establish sales, marketing, distribution and other commercial infrastructure to commercialize any additional products for which we may obtain marketing approval; require the manufacture of larger quantities of product candidates for clinical development and, potentially, commercialization; maintain, expand and protect our intellectual property portfolio; hire and retain additional personnel, such as clinical, quality control, regulatory and scientific personnel; add operational, financial and management information systems and personnel, including personnel to support our product development and add equipment and physical infrastructure to support our research and development programs and commercialization.

Financing Agreement and Credit Facility

On May 13, 2024, we entered into a financing agreement, or the Sixth Street Financing Agreement, with certain of our material subsidiaries as guarantors party thereto, the lenders party thereto, or the Lenders, and Sixth Street Lending Partners, as the administrative agent and collateral agent for the Lenders.

The Sixth Street Financing Agreement provided for a senior secured term loan facility of up to $475.0 million, or the Credit Facility, consisting of an initial draw of $375.0 million at closing and a potential additional $100.0 million draw at our option upon satisfaction of a $50.0 million minimum cash requirement and a requirement that our trailing three-month sales of SYFOVRE is at least $180.0 million prior to the $100.0 million draw. We did not draw down the additional $100.0 million and the option expired on September 30, 2025.

The Credit Facility matures on May 13, 2030, or the "Maturity Date" and bears interest an annual rate equal to 3-month Term SOFR (subject to 1.00% floor), plus 5.75%. Certain additional commitment and undrawn amount fees are also payable in connection with the Credit Facility.

The net proceeds from the initial draw of the Credit Facility were approximately $358.2 million, net of $16.8 million of issuance costs. We used the majority of the proceeds of the draw at closing to buy out our remaining obligations to SFJ, in the amount of approximately $326.5 million.

The Credit Facility does not provide for scheduled amortization payments during the term. All principal will be due on the Maturity Date. We have the right to prepay loans under the Credit Facility at any time. We are required to repay loans under the Credit Facility with proceeds from certain asset sales, condemnation events and extraordinary receipts, subject, in some cases, to reinvestment rights. Repayments are subject to a prepayment premium. Repayments may be made after the first year of the loan and are subject to a prepayment premium up to 3% depending on timing.

On July 1, 2025, the lenders and Sixth Street Financing consented to the Royalty Agreement with Sobi, or the Sixth Street Consent, and, in connection with that the Sixth Street Consent, we agreed to extend by one year from the effective date of the Consent the periods in which certain prepayment premiums would be owed under the Sixth Street Financing Agreement. This effectively extended the period the prepayment premium would be owed from one year after the date of the initial draw, or May 13, 2024, to one year after the effective date of the Sixth Street Consent, or July 1, 2025. We expect to pay a prepayment penalty of $11.3 million in connection with the Merger Agreement and upon consummation of the Merger as all amounts outstanding under the Sixth Street Financing Agreement are expected to be satisfied in full, and we do not expect any indebtedness to remain outstanding following the closing of the Merger.

All obligations under the Sixth Street Financing Agreement are secured on a first-priority basis, subject to certain exceptions, by security interests in substantially all of our assets and assets of our material subsidiaries, including our intellectual property, and are guaranteed by our material subsidiaries, including foreign subsidiaries, subject to certain exceptions.

The Sixth Street Financing Agreement contains customary covenants, including, without limitation, a financial covenant to maintain liquidity of at least $50.0 million if our market capitalization is below $3.0 billion, and negative covenants that, subject to

certain exceptions, restrict indebtedness, liens, investments (including acquisitions), fundamental changes, asset sales and licensing transactions, dividends, modifications to material agreements, payment of subordinated indebtedness, and other matters customarily restricted in such agreements. Among other permissions, we are permitted, on terms and conditions set forth on the Sixth Street Financing Agreement, to enter into a separate asset-based financing arrangement with a third party in an amount of up to $100.0 million, which amount is increased to $200.0 million upon certain sales or market capitalization thresholds, and to have outstanding convertible unsecured notes in an amount equal to the greater of $400.0 million and 10% of our market capitalization, but not to exceed $600.0 million. We are subject to restrictions on sales and licensing transactions with respect to our core intellectual property,

defined to include SYFOVRE, EMPAVELI, and other pegcetacoplan product assets, subject to certain exceptions, including certain transactions related to areas outside the United States and Europe.

The Sixth Street Financing Agreement also contains certain events of default after which loans under the Credit Facility may be due and payable immediately, including payment defaults, material inaccuracy of representations and warranties, covenant defaults, bankruptcy and insolvency proceedings, cross-defaults to certain other agreements, judgments against us and our subsidiaries, and change of control.

On May 13, 2024, we used proceeds from the Sixth Street Financing Agreement to buy out our remaining obligations owed to SFJ, in the amount of approximately $326.5 million. The buyout of the SFJ development liability eliminated the remaining $366.0 million in payments to SFJ, including a total of approximately $200.0 million payable in 2024 and 2025.

Convertible Notes

On September 16, 2019, we completed a private offering of convertible notes, or the 2019 Convertible Notes, with an aggregate principal amount of $220.0 million issued pursuant to an indenture, or the Indenture, with U.S. Bank National Association, as trustee.

The net proceeds from the sale of the 2019 Convertible Notes were approximately $212.9 million after deducting the initial purchasers' discounts and commissions of $6.6 million and offering expenses of $0.5 million. We used $28.4 million of the net proceeds from the sale of the 2019 Convertible Notes to pay the cost of the capped call transactions in September 2019 described below.

On May 12, 2020, we issued convertible notes, or the 2020 Convertible Notes, with an aggregate principal amount of $300.0 million. The net proceeds from the sale of the 2020 Convertible Notes were approximately $322.9 million after deducting the purchasers' discounts and commission of $5.7 million and offering expenses of $0.3 million. We used $43.1 million of the net proceeds from the sale to pay the cost of the additional capped call transactions in May 2020 described below.

The 2019 Convertible Notes and the 2020 Convertible Notes are referred to together as the Convertible Notes. The Convertible Notes are our senior unsecured obligations and bear interest at a rate of 3.5% per year payable semiannually in arrears on March 15 and September 15 of each year, beginning on March 15, 2020. The Convertible Notes will mature on September 15, 2026, unless converted earlier, redeemed or repurchased in accordance with their terms.

The Convertible Notes are convertible into shares of our common stock at an initial conversion rate of 25.3405 shares per $1,000 principal amount of notes (equivalent to an initial conversion price of approximately $39.4625 per share of common stock). The conversion rate is subject to customary anti-dilution adjustments. In addition, following certain events that occur prior to the maturity date or if we deliver a notice of redemption, we will increase the conversion rate for a holder who elects to convert its Convertible Notes in connection with such corporate event or a notice of redemption, as the case may be, in certain circumstances as provided in the Indenture.

The Holders' Conversion Rights

Prior to March 15, 2026, the Convertible Notes were convertible only under specified circumstances. During 2021 and 2022, holders of the 2019 Convertible Notes and the 2020 Convertible Notes converted approximately $425.4 million in aggregate principal amount into a total of 12,926,104 shares of our common stock. We accounted for these exchanges as induced conversions, resulting in the expensing of the fair value of shares issued in excess of the original terms of the Convertible Notes.

None of the circumstances were achieved as of December 31, 2025 and as such, the conditional conversion feature of the Convertible Notes was not triggered as of December 31, 2025.

From March 15, 2026 until the close of business on the second scheduled trading day immediately preceding the maturity date of the Convertible Notes, holders may convert the Convertible Notes at any time regardless of the foregoing circumstances. Upon conversion of the Convertible Notes, we will pay and deliver a combination of cash and shares of common stock.

The Company's Redemptions Rights

As of September 20, 2023, we may redeem for cash all or a portion of the Convertible Notes, at our option, if the last reported sale price of our common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive), including the trading day immediately preceding the date on which we provide a notice of redemption, during any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which we provide notice of redemption. The redemption price will be equal to 100% of the principal amount of the Convertible Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. If we call any Convertible Notes for redemption, it will constitute a

"make-whole fundamental change" with respect to such Convertible Notes, in which case the conversion rate applicable to the conversion of such Notes, if converted in connection with the redemption, will be increased in certain circumstances. We have not called for redemption any of the Convertible Notes as of March 31, 2026.

If we undergo a "fundamental change," as defined in the Indenture, prior to maturity, subject to certain conditions, holders may require us to repurchase for cash all or any portion of their Convertible Notes at a fundamental change repurchase price equal to 100 % of the principal amount of the notes to be repurchased, plus any accrued and unpaid interest to, but excluding, the fundamental change repurchase date. The consummation of the Offer and the Merger may each constitute a "fundamental change" under the Indenture. In addition, the Offer and the Merger may each constitute a "make-whole fundamental change" (as defined in the Indenture), which may give holders the right to convert such Convertible Notes at an increased conversion rate in accordance with the terms of the Indenture.

As of March 31, 2026, we held in treasury Convertible Notes in principal amount of $425.4 million which notes had not been cancelled.

We classified the Convertible Notes as current liabilities as of March 31, 2026 and December 31, 2025 on our consolidated balance sheet, as the Convertible Notes mature on September 15, 2026.

Capped Call Transactions

In September 2019 and May 2020, concurrently with the pricing of the 2019 Convertible Notes and 2020 Convertible Notes, respectively, we entered into capped call transactions with two counterparties. The capped call transactions are expected generally to reduce the potential dilution to our common stock upon any conversion of Convertible Notes and/or offset any cash payments we are required to make in excess of the principal amount of converted Convertible Notes, as the case may be, in the event that the market price per share of our common stock, as measured under the terms of the capped call transactions, is greater than the strike price of the capped call transactions, which is initially $39.4625, the conversion price of the Convertible Notes, and is subject to anti-dilution adjustments substantially similar to those applicable to the conversion rate of such Convertible Notes. If, however, the market price per share of our common stock, as measured under the terms of the capped call transactions, exceeds $63.14, the cap price of the capped call transactions, there would nevertheless be dilution and/or there would not be an offset of such potential cash payments, in each case, to the extent that such market price exceeds the cap price of the capped call transactions.

On February 27, 2024, we unwound a portion of the capped call transactions with the capped call counterparties, which resulted in cash proceeds to us of $98.8 million. The unwind transactions were settled at a volume-weighted average price per share of $64.11 on March 8, 2024.

In connection with the Merger Agreement and prior to the Effective Time of the Merger, we have agreed to use reasonable best efforts to cooperate with Parent, at Parent's written request, to enter into arrangements with the counterparties to the capped call transactions to cause such transactions to be exercised, settled, terminated or cancelled as of the Effective Time, with the calculation and settlement of any amounts payable thereunder to be payable only in cash and subject to the mutual agreement of Parent, us and the respective counterparties.

Collaboration Agreement with Sobi

On October 27, 2020, we entered into the Sobi Collaboration Agreement, concerning the development and commercialization of pegcetacoplan and specified other structurally and functionally similar compstatin analogues or derivatives for use systemically or for local non-ophthalmological administration, collectively referred to as the Licensed Products. We granted Sobi an exclusive (subject to certain rights retained by us), sublicensable license of certain patent rights and know-how to develop and commercialize Licensed Products in all countries outside of the United States. We retained the right to commercialize Licensed Products in the United States, and, subject to specified limitations, to develop Licensed Products worldwide for commercialization in the United States. Under the Sobi Collaboration Agreement, Sobi made an upfront payment of $250.0 million in November 2020, and agreed to pay up to an aggregate of $915.0 million upon the achievement of specified one-time regulatory and commercial milestone events, including a $50.0 million milestone payable following the first regulatory and reimbursement approval of systemic pegcetacoplan in any major European country, and to reimburse us for up to $80.0 million in development costs. Since contract inception, we have recognized $65.0 million in contra-research and development expenses and waived the remaining $15.0 million in connection with the decision to discontinue the CAD program.

The European Commission approved systemic Aspaveli (pegcetacoplan) for the treatment of adults with PNH in December 2021. In March 2022, we earned a $50.0 million payment from Sobi related to the first regulatory and reimbursement milestone in Europe, which we received in April 2022. Through June 30, 2025, we were also entitled to receive tiered, double-digit royalties (ranging from

high teens to high twenties) on sales of Licensed Products outside of the United States, subject to customary deductions and third-party payment obligations, until the latest to occur of: (i) expiration of the last-to-expire of specified licensed patent rights; (ii) expiration of regulatory exclusivity; and (iii) ten (10) years after the first commercial sale of the applicable licensed product, in each case on a licensed product-by-licensed product and country-by-country basis. On July 1, 2025, we and certain of our subsidiaries entered into the Royalty Agreement, under which we agreed to reduce Sobi's royalty payment obligations under the Collaboration Agreement by 90%, effective as of July 1, 2025, subject to defined caps tied to Aspaveli's performance, including an initial cap of 1.45x of the amounts paid by Sobi to us under the Royalty Agreement. If a cap is met, Sobi's royalty payment obligations under the Sobi Collaboration Agreement will revert to 100%. We remain responsible for our license fee obligations (including royalty obligations) to the Trustees of Penn as a licensor of ours.

In January 2026, Sobi received EMA approval of Aspaveli for C3G and primary IC-MPGN. Sobi paid us an additional $25.0 million in February 2026 pursuant to the Royalty Agreement and an additional $30.0 million regulatory development milestone in April 2026 pursuant to the Sobi Collaboration Agreement. This $55.0 million is recorded as licensing and other revenue on our consolidated statement of operations and comprehensive income/(loss) in the first quarter of 2026.

Financial Operations Overview

Revenue

Our revenues consist of product sales of EMPAVELI and SYFOVRE, and revenues derived from the Sobi Collaboration Agreement.

Revenue is recognized when, or as, we satisfy a performance obligation by transferring a promised good or service to a customer. An asset is transferred when, or as, the customer obtains control of that asset. For performance obligations that are satisfied over time, we recognize revenue using an input or output measure of progress that best depicts the satisfaction of the relevant performance obligation.

Product Revenues

Product revenue is derived from our sales of our commercial products, EMPAVELI and SYFOVRE, primarily recognized in the United States.

Licensing and Other Revenue

Licensing and other revenue is derived from our collaboration agreement with Sobi concerning the development and commercialization of pegcetacoplan and specified other compstatin analogues or derivatives for use systemically or for local non-ophthalmic administration.

Cost of Sales

Cost of sales consists primarily of costs associated with the manufacturing of EMPAVELI and SYFOVRE, product supplied to Sobi, and royalties owed to our licensor for such sales, and certain period costs.

Research and Development Expenses

Research and development expenses consist primarily of costs incurred for our research activities, including our drug discovery efforts, and the development of our product candidates, which include:

Research and development costs are expensed as incurred. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are deferred and capitalized. The capitalized amounts are expensed as the

related goods are delivered or the services are performed. We have not provided program costs since inception because historically we have not tracked or recorded our research and development expenses on a program-by-program basis from inception.

The successful development of our product candidates in clinical development is highly uncertain. Accordingly, at this time, we cannot reasonably estimate the nature, timing and costs of the efforts that will be necessary to complete the remainder of the clinical development of these product candidates. We are also unable to predict when, if ever, material net cash inflows will commence from pegcetacoplan in other jurisdictions and indications or any other potential product candidates. This is due to the numerous risks and uncertainties associated with developing therapeutics, including the uncertainties of:

A change in the outcome of any of these variables with respect to the development of any of our product candidates would significantly change the costs and timing associated with the development of that product candidate.

Research and development activities are central to our business model. Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials. So long as we continue to operate as an independent company, we expect research and development costs to increase for the foreseeable future as our product candidate development programs continue to progress and expand. However, we do not believe that it is possible at this time to accurately project total program-specific expenses through commercialization. There are numerous factors associated with the successful commercialization of any of our product candidates, including future trial design and various regulatory requirements, many of which cannot be determined with accuracy at this time based on our stage of development. Additionally, future commercial and regulatory factors beyond our control will impact our clinical development programs and plans.

Selling, General and Administrative Expenses

Selling, general and administrative expenses consist primarily of costs associated with the commercialization of approved products and general and administrative costs to support operations, including salaries, bonuses, benefits and share-based compensation. Selling expenses include product marketing, sales operations costs, and other costs incurred to support our sales efforts. General and administrative expenses include corporate support functions such as executive management, finance and accounting, business development, legal, human resources, information technology, and associated external costs to support those functions. Other significant costs include costs associated with medical affairs, drug safety and pharmacovigilance, quality and regulatory costs not otherwise included in research and development expenses, legal fees relating to patent and corporate matters, and fees for accounting and consulting services. Marketing and advertising costs include marketing literature, promotional activities, conferences and seminars, branding and sponsorships.

So long as we continue to operate as an independent company, we expect our selling, general and administrative expenses will increase in the future to support continued research and commercial activities for our approved products, potential commercialization of our product candidates and costs of operating as a public company.

Critical Accounting Estimates

This discussion and analysis of our financial condition and results of operations is based on our financial statements, which we have prepared in accordance with U.S. generally accepted accounting principles. The preparation of these financial statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of expenses during the reported periods. On an ongoing basis, we evaluate our estimates and judgments, including those related to product revenue, inventory and accrued research and development expenses, which we described in our 2025 Annual Report on Form 10-K. We base our estimates on historical experience and on various other factors that we believe are reasonable under the circumstances, the results of which form the basis for

making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions.

Our significant accounting policies are described in Note 2 of Part I, Item 1 of this Quarterly Report on Form 10-Q and in Part I, Item 7, "Critical Accounting Estimates" in our 2025 Annual Report on Form 10-K. There have been no changes to our critical accounting policies and estimates since our 2025 Annual Report on Form 10-K.

Results of Operations

Three Months Ended March 31, 2026 and 2025 (in thousands, except percentages)

Product Revenue, Net

Our product revenue, net is derived from EMPAVELI and SYFOVRE sales in the United States. The net product revenue of $192.0 million for the three months ended March 31, 2026, consisted of $41.3 million in net product revenue from sales of EMPAVELI and $150.7 million in net product revenue from sales of SYFOVRE. The net product revenue of $149.9 million for the three months ended March 31, 2025, consisted of $19.7 million in net product revenue from sales of EMPAVELI and $130.2 million in net product revenue from sales of SYFOVRE. The increase of $42.1 million primarily relates to increases in volume, which were partially offset by an increase in rebates.

Licensing and Other Revenue

Licensing and other revenue of $76.3 million for the three months ended March 31, 2026 consisted of $20.5 million in revenue from product supplied to Sobi, $0.8 million in royalty revenue from Sobi, $25.0 million related to the Royalty Agreement and $30.0 million in regulatory development milestones. Licensing and other revenue of $16.9 million for the three months ended March 31, 2025 consisted of $10.8 million in revenue from product supplied to Sobi and $6.1 million in royalty revenue from Sobi. The increase in licensing and other revenue was primarily driven by the one-time $25.0 million earned due to regulatory approval of Aspaveli in EMA for C3G and primary IC-MPGN under the Royalty Agreement, the corresponding $30.0 million regulatory development milestone earned under the Sobi Collaboration Agreement, and an increase of $9.7 million in product supply to Sobi. These increases were partially offset by a decrease in royalty revenue of $5.3 million given the Royalty Agreement reduced Sobi's royalty rates by 90%.

Cost of Sales

Cost of sales increased by $6.2 million, primarily due to a $3.2 million increase associated with higher volumes from commercial sales and product provided under our patient assistance programs, a $6.6 million increase related to higher volume of product supplied to Sobi and a $4.9 million increase in royalty expenses. The increases were partially offset by a $7.7 million decrease in expenses incurred related to excess, obsolete or scrapped inventory.

In addition, prior to receiving FDA approval for EMPAVELI and SYFOVRE, the costs associated with the manufacturing of EMPAVELI and SYFOVRE inventory were expensed as incurred as research and development expense. This resulted in inventory

being sold during the three months ended March 31, 2026 and 2025 for which a portion of the costs had been previously expensed prior to FDA approval. This did not materially impact cost of sales for the three months ended March 31, 2026 and 2025. We expect this to continue to impact the cost of sales and research and development expense as we continue to sell to customers or use in preclinical or clinical studies. As of March 31, 2026 and December 31, 2025, the remaining pre-FDA approved inventory was $16.8 million and $17.8 million, respectively, which primarily consisted of raw materials and semi-finished goods.

Research and Development Expenses

The following table summarizes our research and development expenses incurred during the three months ended March 31, 2026 and 2025 (in thousands, except percentages):

Research and development expenses decreased by $9.5 million for the three months ended March 31, 2026, compared to the three months ended March 31, 2025. The decrease in research and development expenses was primarily attributable to a decrease of $8.6 million in program-specific external costs and a decrease of $1.5 million related to compensation and related personnel costs. The decreases were partially offset by a $0.8 million increase in non-program specific external costs.

The decrease in our program-specific external costs of $8.6 million was driven by a $4.6 million decrease in C3G and primary IC-MPGN costs due to lower costs related to the VALIANT study as the Phase 3 trial was completed and is winding down, and a $6.8 million decrease in other development and discovery programs, primarily due to upfront milestone payments of $7.0 million incurred during the first quarter of 2025 related to the Beam FcRn program. These decreases were partially offset by an increase of $1.5 million in PNH and an increase of $1.1 million in GA costs associated with the product lifecycle development.

The decrease in compensation and related personnel costs was driven by a decrease of $2.2 million in share-based compensation. The decrease was partially offset by a $0.8 million increase in salaries and benefits.

Selling, General and Administrative Expenses

Selling, general and administrative expenses decreased by $5.0 million for the three months ended March 31, 2026, compared to the three months ended March 31, 2025. The decrease was primarily attributable to a decrease of $15.5 million in general commercial activities and decrease of $1.2 million in factoring fees. These decreases were partially offset by an increase of $2.7 million in personnel related costs, an increase of $3.8 million in professional and consulting fees driven by costs associated with the Merger Agreement, and an increase of $5.2 million in other general and administrative expenses, including office costs, travel and insurance.

Liquidity and Capital Resources

Sources of Liquidity

To date, we have financed our operations primarily through $2.6 billion in net proceeds from public offerings of our common stock and pre-funded warrants to purchase common stock, $745.5 million in payments under our Sobi Royalty and Collaboration Agreements, $532.5 million under various credit arrangements, including with Sixth Street and SFJ, and $98.8 million relating to the unwinding of certain capped call transactions in March 2024, as well as from the proceeds of our operations. To date, we have

exchanged $425.4 million and converted $0.7 million of aggregate principal amount of our Convertible Notes for shares of our common stock.

In May 2024, we entered into the Sixth Street Financing Agreement, which provided for the Credit Facility, consisting of an initial draw of $375.0 million at closing and a potential additional $100.0 million draw at our option upon satisfaction of a $50.0 million minimum cash requirement and a requirement that our trailing three-month sales of SYFOVRE is at least $180.0 million prior to the $100.0 million draw by September 30, 2025. We did not draw down the additional $100.0 million and the option expired on September 30, 2025.

We are permitted under the Sixth Street Financing Agreement to enter into a separate asset-based financing arrangement with a third party in an amount of up to $100.0 million, which amount is increased to $200.0 million upon certain sales or market capitalization thresholds, and to have outstanding convertible unsecured notes in an amount equal to the greater of $400.0 million and 10% of our market capitalization, but not to exceed $600.0 million.

In August 2024, we entered into an agreement, or the Factoring Agreement, to sell certain accounts receivable to a third-party financial institution at a discount to the face value of the accounts receivable. Under the Factoring Agreement, the maximum amount of outstanding accounts receivables sold at any time is $100.0 million. There were no accounts receivable sold as of March 31, 2026 or as of December 31, 2025.

In November 2023, we entered into a sales agreement, or the sales agreement, with Cowen and Company, LLC, or Cowen, as agent, pursuant to which we may offer and sell shares of our common stock having an aggregate offering of up to $300.0 million from time to time. Any sales made under the sales agreement will be made at market prices by any method that is deemed to be an "at the market offering" as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933. Any sales under the sales agreement will be made pursuant to our registration statement on Form S-3, which became effective on February 22, 2023. We agreed to pay Cowen compensation of up to 3.0% of the gross proceeds of the sale of shares made under the sales agreement. We did not make any sales under the sales agreement during the three months ended March 31, 2026.

In February 2023, we issued and sold 4,007,936 shares of our common stock and, in lieu of common stock to investors who so chose, pre-funded warrants to purchase 2,380,956 shares of our common stock in a follow-on offering, including 833,333 shares sold pursuant to the underwriters' exercise in full of their option to purchase additional shares of common stock. The price to the public of the shares of common stock was $63.00 per share and the price to the public of the pre-funded warrants was $62.9999 per pre-funded warrant. The pre-funded warrants have an exercise price equal to $0.0001 per share and do not expire. The pre-funded warrants were accounted for as equity instruments. We received total net proceeds of $384.4 million, after deducting underwriting discounts and commissions of $18.8 million and offering cost of $0.3 million. For the period ended December 31, 2024, 2,299,991 shares of common stock were issued upon the exercise of pre-funded warrants. For the period ended March 31, 2026, 80,956 shares of common stock were issued upon the exercise of pre-funded warrants. As of March 31, 2026, no pre-funded warrants to purchase shares of our common stock were still outstanding.

In February 2024, we entered into agreements with the capped call counterparties to unwind a portion of the capped call transactions. The unwind agreements applied to the portion of the capped call transactions in a notional amount corresponding to the $426.1 million principal amount of Convertible Notes that we held in treasury as of December 31, 2024 or have been previously converted. The unwind transactions were settled at volume-weighted average price per share of $64.11, which resulted in cash proceeds to us of $98.8 million. As of March 31, 2026 the remaining capped call transactions had a notional amount corresponding to $93.9 million principal amount of Convertible Notes, which expire in September 2026.

Cash Flows

The following table provides information regarding our cash flows for the three months ended March 31, 2026 and 2025 (in thousands):

Net Cash Used in Operating Activities

Net cash used in operating activities was $61.0 million for the three months ended March 31, 2026 and consisted primarily of a net income of $18.7 million adjusted for $26.1 million of non-cash items, including share-based compensation expense of $25.2 million and depreciation expense of $0.3 million. Further, it included a net increase in operating assets and liabilities of $105.7 million, which was driven by an increase in accounts receivable of $74.1 million, a decrease in inventory of $18.8 million, an increase in prepaid and other current assets of $11.3 million, a decrease in accounts payable of $7.7 million, and a decrease in accrued expenses of $31.2 million.

Net cash used in operating activities was $53.4 million for the three months ended March 31, 2025 and consisted primarily of a net loss of $92.2 million adjusted for $28.4 million of non-cash items, including share-based compensation expense of $27.4 million and depreciation expense of $0.4 million. Further, it included a net decrease in operating assets and liabilities of $10.4 million, which was driven by a decrease in accounts receivable of $29.7 million, a decrease in inventory of $14.0 million, an increase in prepaid and other current assets of $20.1 million, an increase in accounts payable of $16.7 million, and a decrease in accrued expenses of $30.2 million. The change in accounts receivable was primarily driven by the derecognition of certain accounts receivable under our Factoring Agreement.

Net Cash Provided by Financing Activities

Net cash provided by financing activities was $0.1 million and $0.3 million during the three months ended March 31, 2026 and 2025, respectively. Financing activities during the periods presented primarily consisted of proceeds from the exercise of stock options.

Funding Requirements

We expect to continue to incur expenses to support our ongoing commercial activities related to product manufacturing, marketing, sales and distribution of EMPAVELI for PNH, C3G and primary IC-MPGN, and SYFOVRE for GA. In addition, we expect to continue to incur expenses as we prioritize the ongoing development of systemic pegcetacoplan and focus our research initiatives on high potential opportunities.

We believe that our cash and cash equivalents as of March 31, 2026, together with the cash that we anticipate will be generated from sales of EMPAVELI and SYFOVRE, will be sufficient to fund our projected operating expenses and capital expenditure requirements for at least the next 12 months, as well as our anticipated longer-term cash requirements and obligations. Our expectations regarding our short-term and long-term funding requirements are based on assumptions that may prove to be wrong, and we may need additional capital resources to fund our operating plans and capital expenditure requirements.

We are devoting substantial resources to the commercial infrastructure for SYFOVRE for GA and EMPAVELI for the treatment of PNH, C3G and primary IC-MPGN. We are also devoting substantial resources to our pivotal clinical trials of EMPAVELI for the treatment of FSGS and DGF, and the development of our product candidates. Because of the numerous risks and uncertainties associated with the commercialization of EMPAVELI and SYFOVRE and the development of our product candidates, and because the extent to which we may enter into collaborations with third parties for any of these activities is unknown, we are unable to estimate the amounts of increased capital outlays and operating expenses associated with the research, development and commercialization. Our future funding requirements and long-term capital requirements will depend on many factors, including:

If our cash and cash equivalents, and cash generated from sales of EMPAVELI and SYFOVRE are not sufficient to fund our planned expenditures, we will need to finance our cash needs through external sources of funds, which may include equity offerings, debt financings, collaborations, strategic alliances or licensing arrangements. We currently do not have any committed external source of funds.

If we are unable to generate sufficient funds from sales of EMPAVELI and SYFOVRE, or raise additional funds when needed, we may be required to delay, limit, reduce or terminate our product development or future commercialization efforts or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Contractual Obligations

The disclosure of our contractual obligations and commitments is set forth under the heading "Management's Discussion and Analysis of Financial Condition and Results of Operations-Contractual Obligations" in our 2025 Annual Report on Form 10-K. See Note 11. Commitments and Contingencies in the Notes to Unaudited Condensed Consolidated Financial Statements in Part I, Item I of this Form 10-Q for a discussion of obligations and commitments.