Alector, Inc. (ALEC)

CIK: 0001653087. SIC: 2836 Biological Products, (No Diagnostic Substances). Latest 10-K as of: 2026-02-25.

SIC breadcrumb: Manufacturing > Chemicals And Allied Products > SIC 2836 Biological Products, (No Diagnostic Substances)

SEC company page: https://www.sec.gov/edgar/browse/?CIK=1653087. Latest filing source: 0001193125-26-071593.

Selected Fundamentals

Financials

Annual standardized facts from SEC companyfacts as of latest extracted filing date 2026-02-25. Source: https://data.sec.gov/api/xbrl/companyfacts/CIK0001653087.json. Derived margins, ratios, and free cash flow are computed from the extracted annual SEC facts.

Flow metrics use full-year FY periods from 10-K/10-K/A filings; balance-sheet metrics use FY-end instants. Free cash flow = operating cash flow - capital expenditures. Missing metrics are omitted rather than fabricated.

Ratios

ROE and ROA use period-end equity/assets. Liabilities / equity uses total liabilities divided by stockholders' equity. Current ratio uses current assets divided by current liabilities when both are reported.

Financial Charts

Quarterly

Quarterly standardized facts from SEC companyfacts as of latest extracted filing date 2026-05-07. Source: https://data.sec.gov/api/xbrl/companyfacts/CIK0001653087.json.

Flow metrics use discrete quarter-length periods from 10-Q/10-Q/A filings. Q4 revenue and net income are derived only when annual FY and nine-month YTD facts exist for the same fiscal year; derived Q4 values are labeled. EPS Q4 is not derived.

Quarterly Charts

Macro Cross-References

• CPIAUCSL - Consumer Price Index for All Urban Consumers: All Items in U.S. City Average
• UNRATE - Unemployment Rate
• FEDFUNDS - Federal Funds Effective Rate
• CES0500000003 - Average Hourly Earnings of All Employees, Total Private
• DFEDTARU - Federal Funds Target Range - Upper Limit
• DFEDTARL - Federal Funds Target Range - Lower Limit
• DGS3MO - Market Yield on U.S. Treasury Securities at 3-Month Constant Maturity
• DGS2 - Market Yield on U.S. Treasury Securities at 2-Year Constant Maturity
• DGS10 - Market Yield on U.S. Treasury Securities at 10-Year Constant Maturity
• DGS30 - Market Yield on U.S. Treasury Securities at 30-Year Constant Maturity
• T10Y2Y - 10-Year Treasury Constant Maturity Minus 2-Year Treasury Constant Maturity
• CPILFESL - Consumer Price Index for All Urban Consumers: All Items Less Food and Energy
• CPIUFDSL - Consumer Price Index for All Urban Consumers: Food
• CPIENGSL - Consumer Price Index for All Urban Consumers: Energy
• CUSR0000SAH1 - Consumer Price Index for All Urban Consumers: Shelter
• PCEPI - Personal Consumption Expenditures: Chain-type Price Index
• PCEPILFE - Personal Consumption Expenditures Excluding Food and Energy: Chain-type Price Index
• PPIACO - Producer Price Index by Commodity: All Commodities
• T10YIE - 10-Year Breakeven Inflation Rate
• U6RATE - Total Unemployed, Plus All Marginally Attached Workers Plus Total Employed Part Time for Economic Reasons
• PAYEMS - All Employees, Total Nonfarm
• CIVPART - Labor Force Participation Rate
• EMRATIO - Employment-Population Ratio
• UNEMPLOY - Unemployed
• CE16OV - Employment Level
• ICSA - Initial Claims
• JTSJOL - Job Openings: Total Nonfarm
• JTSQUR - Quits: Total Nonfarm
• GDPC1 - Real Gross Domestic Product
• A191RL1Q225SBEA - Real Gross Domestic Product: Percent Change from Preceding Period
• INDPRO - Industrial Production: Total Index
• TCU - Capacity Utilization: Total Index
• HOUST - New Privately-Owned Housing Units Started: Total Units
• PERMIT - New Privately-Owned Housing Units Authorized in Permit-Issuing Places: Total Units
• RSAFS - Advance Retail Sales: Retail Trade
• PCE - Personal Consumption Expenditures
• DSPIC96 - Real Disposable Personal Income
• PSAVERT - Personal Saving Rate
• M2SL - M2
• BOPGSTB - U.S. International Trade in Goods and Services: Balance
• MSPUS - Median Sales Price of Houses Sold for the United States
• HSN1F - New One Family Houses Sold: United States
• RHORUSQ156N - Homeownership Rate in the United States
• TTLCONS - Total Construction Spending: Total Construction in the United States
• RRVRUSQ156N - Rental Vacancy Rate in the United States
• TOTALSL - Total Consumer Credit Owned and Securitized
• REVOLSL - Revolving Consumer Credit Owned and Securitized
• DRCCLACBS - Delinquency Rate on Credit Card Loans, All Commercial Banks
• GDP - Gross Domestic Product
• GPDI - Gross Private Domestic Investment
• GCE - Government Consumption Expenditures and Gross Investment
• PCEC - Personal Consumption Expenditures
• NETEXP - Net Exports of Goods and Services
• GFDEBTN - Federal Debt: Total Public Debt
• GFDEGDQ188S - Federal Debt: Total Public Debt as Percent of Gross Domestic Product
• FYFSD - Federal Surplus or Deficit
• FGRECPT - Federal Government Current Receipts
• FGEXPND - Federal Government: Current Expenditures
• MANEMP - All Employees, Manufacturing
• USCONS - All Employees, Construction
• USTRADE - All Employees, Retail Trade
• USFIRE - All Employees, Financial Activities
• USGOVT - All Employees, Government
• AWHAETP - Average Weekly Hours of All Employees, Total Private
• DGORDER - Manufacturers' New Orders: Durable Goods
• NEWORDER - Manufacturers' New Orders: Nondefense Capital Goods Excluding Aircraft
• BUSINV - Total Business Inventories
• EXPGS - Exports of Goods and Services
• IMPGS - Imports of Goods and Services
• IR - Import Price Index (End Use): All Commodities
• PPIFIS - Producer Price Index by Commodity: Final Demand

Latest quarter (10-Q)

Latest 10-Q source: 0001193125-26-211981.

Extracted structurally from real Item 2 body heading to real Item 3/4 boundary. Published MD&A gate trimmed front/tail over-capture. Confidence: high. Filing date: 2026-05-07. Report date: 2026-03-31.

Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

You should read the following discussion and analysis of our financial condition and results of operations together with our condensed consolidated financial statements and related notes included elsewhere in this Quarterly Report on Form 10-Q. This discussion contains forward-looking statements that involve risks and uncertainties, including those described in the section titled “Special Note Regarding Forward-Looking Statements.” Our actual results and the timing of selected events could differ materially from those discussed below. Factors that could cause or contribute to such differences include, but are not limited to, those identified below and those set forth under the section titled “Risk Factors” included elsewhere in this report.

Overview

We are a biotechnology company developing therapies for neurodegenerative diseases, with a focus on areas of high unmet medical need. Our work is informed by advances in disease biology, including the roles of misfolded or deficient proteins, lysosomal dysfunction, and immune and neuronal pathway disruption.

Our objective is to develop product candidates that address disease through targeted mechanisms, such as removing pathogenic proteins, replacing deficient proteins, and restoring normal cellular function. We are advancing a portfolio of programs focused on genetically validated targets, supported by our experience in drug development, protein engineering, antibody discovery, and biomarker assessment.

A key component of our strategy is the development and application of our Alector Brain Carrier (ABC) platform, a proprietary blood-brain barrier (BBB) delivery technology designed to improve central nervous system exposure across multiple therapeutic modalities. Built on the core design principles of versatility, translatability, and differentiated binding to a distinct region of the transferrin receptor (TfR), ABC is intended to support the targeted delivery of therapeutics to the brain and to optimize their safety and efficacy at lower doses. With a wide range of TfR binding affinities and binding kinetics, and the ability to target a distinct epitope of TfR, the platform can be aligned with the requirements of diverse therapeutic cargos, including antibodies, enzymes, proteins, and siRNA. The platform’s TfR binding domain is further adaptable to diverse engineered formats, enabling broad applicability to our product candidates. By leveraging these proprietary features, we aim to achieve efficient transport of our product candidates across the BBB with the goal of balancing brain uptake, potency, and safety. This next generation pipeline, built on the ABC platform and distinct from our prior clinical programs, positions us to develop therapeutic candidates for a range of neurodegenerative diseases.

AL037/AL137 Program

Our AL037/AL137 program, which pairs our proprietary anti-amyloid beta (Aβ) antibody with our proprietary ABC platform, is in preclinical development for Alzheimer's disease (AD). It is designed to remove brain Aβ plaques, with the goal of minimizing treatment-related incidence and/or severity of amyloid-related imaging abnormalities (ARIA), and to enable subcutaneous delivery. AL037 and AL137 each feature the same high-affinity, fully human antibody that selectively binds PyroGlu3, a validated epitope on the toxic form of Aβ found in plaques, and a fully active effector function that enables maximal recruitment of myeloid cells to remove plaques. AL037 and AL137 both incorporate Alector’s proprietary ABC, with TfR binding domains that bind the same epitope on TfR but with different affinities and binding kinetics, to balance brain penetration and plaque removal with minimized hematologic adverse effects. In preclinical studies to date, AL037 and AL137 have demonstrated robust brain penetration in non-human primates, and a murine surrogate of AL037/AL137 has demonstrated amyloid beta 42 reduction in murine studies.

Following successful completion of IND-enabling studies, we intend to select AL037 or AL137 for submission of an Investigational New Drug (IND) application, targeted for the first quarter of 2027.

AL050 Program

AL050 is a glucocerebrosidase (GCase) enzyme replacement therapy paired with our proprietary ABC technology in preclinical development for Parkinson’s disease and Lewy body dementia in patients having GBA1 gene mutations that lead to reduced GCase activity. AL050 features an engineered GCase with improved activity and stability, a silenced effector function to maximize safety, and Alector’s ABC with a TfR epitope and affinity designed to enhance delivery across the BBB. This mechanism aims to reduce cellular dysfunction and slow disease progression. In preclinical studies to date, AL050 doubled GCase activity in different brain regions in non-human primates without observed adverse effects, including hematologic effects. In a GBA disease mouse model, AL050 surrogate rescued GCase activity and reduced toxic substrate accumulation without abnormal hematologic findings. These data support the potential of AL050 as a therapy for Parkinson’s disease (PD) and Lewy body dementia (LBD) associated with GBA loss of function mutations, and subsequently for idiopathic PD and LBD.

We have selected AL050 as a lead candidate, and we continue to evaluate our timeline to the clinic.

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ABC-Enabled siRNA Platform

We continue to advance our ABC-enabled siRNA platform. The platform is designed for peripheral dosing, offering the potential for more convenient administration compared with traditional intrathecal delivery, as well as the potential for homogeneous drug distribution throughout the brain. Current programs include AL064/AL164, our tau siRNA program for AD and other tauopathies. AL064/AL164 aims to prevent the synthesis of tau mRNA and protein, with the goal of removing toxic tau, suppressing tau protein expression, and slowing cognitive decline in AD. AL064 demonstrated robust tau mRNA knockdown and durable reduction of phospho-Tau 217 in NHP brains. AL064 was modified to incorporate a well-validated chemical modification intended to further optimize siRNA stability, and this modified form of AL064 is advancing into IND-enabling studies as AL164. In addition to AL164, we are advancing early-stage siRNA programs toward lead candidate selection, including ADP062-ABC, an alpha-synuclein siRNA for PD, and ADP065-ABC, an NLRP3 siRNA for multiple neurodegenerative conditions. Together, those programs reflect the broad applicability of the ABC platform across disease mechanisms. We continue to evolve our research and development plans and timing for each of our ABC-enabled siRNA programs.

Nivisnebart

In April 2026, GSK discontinued the global Phase 2 PROGRESS-AD trial of nivisnebart (AL101/GSK4527226), an investigational progranulin-elevating monoclonal antibody, in individuals with early Alzheimer's disease (AD) after a pre-specified interim futility analysis conducted by an Independent Data Monitoring Committee (IDMC), which concluded that the trial was unlikely to meet its primary endpoint of slowing disease progression at completion.

Our operations have been financed primarily through our collaboration with GSK, our previous collaboration with AbbVie, entered into in October 2017 and terminated in February 2025, the issuance and sale of convertible preferred stock and of common stock upon the completion of our initial public offering (IPO), and follow-on equity financings.

To date, we have not had any products approved for sale and have not generated any product or royalty revenue from product sales. Further, we do not expect to generate revenue from product sales until such time, if ever, that we are able to successfully complete the development and obtain marketing approval for one of our product candidates. We will continue to require additional capital to develop our product candidates, advance our research and preclinical programs, and fund operations for the foreseeable future. We have incurred net losses in each year since inception, and we expect to continue to incur net losses for the foreseeable future. Our ability to generate product revenue will depend on the successful development and eventual commercialization of one or more of our product candidates. Our net losses were $22.9 million and $40.5 million for the three months ended March 31, 2026 and 2025, respectively. As of March 31, 2026, we had an accumulated deficit of $995.0 million. Substantially all of our net losses have resulted from costs incurred in connection with our research and development programs and from general and administrative costs associated with our operations. We expect our expenses will increase substantially in connection with our ongoing activities, as we:

•
advance product candidates through preclinical studies and clinical trials;

•
pursue regulatory approval of product candidates;

•
discover, validate, and develop additional product candidates;

•
manufacture drug supply for our research, preclinical studies and clinical trials; and

•
obtain, maintain, and protect our intellectual property portfolio.

On March 7, 2025, we committed to a plan to reduce our workforce by approximately 13% to better align our resources with our strategic priorities, including the advancement of our preclinical and research pipeline. We initiated that reduction in force impacting approximately 25 employees across the organization. On October 21, 2025, we committed to a plan to reduce our workforce by approximately 47% in order to align resources with the Company’s strategic priorities following the results of the Phase 3 INFRONT-3 clinical trial evaluating the safety and efficacy of latozinemab (AL001) in individuals with frontotemporal dementia due to a GRN mutation (FTD-GRN). Our cash, cash equivalents, and marketable securities as of March 31, 2026, totaled $206.5 million, which we anticipate provides runway at least through 2027.

Components of Results of Operations

Revenue

We have not generated any product or royalty revenue from product sales and do not expect to do so in the near future. Our revenue to date has been primarily related to the AbbVie Agreement and GSK Agreement for the license and co-development of product candidates with those parties. We recognized revenue from the upfront payments and the milestone payment received from AbbVie over time as services were provided. We recognize revenue from the upfront payments from

14

GSK at a point in time for a development license and over time for research and development services. Revenues for research and development services are recognized as the program costs are incurred by measuring actual costs incurred to date compared to the overall total expected costs to satisfy the performance obligation.

Under the terms of the GSK Agreement, we received $700 million in upfront payments, of which $500 million was received in August 2021 and $200 million was received in January 2022. In addition, we may be eligible to receive up to an additional $1.5 billion in clinical development, regulatory, and commercial launch-related milestone payments, subject to successful advancement and commercialization of product candidates in multiple indications under the agreement. Alector and GSK are conducting development jointly. In May 2023, we and GSK amended the GSK Agreement. Under the terms of the GSK Amendment, we are responsible for funding GSK’s and our development costs up to $140.5 million for the conduct of the Phase 2 clinical trial of nivisnebart in AD.

In the United States, Alector and GSK will equally share profits and losses from commercialization of product candidates under the agreement. We may opt out of the sharing of development costs and of profit and losses from commercialization in the United States on a product-by-product basis. In such case, we wi

[Excerpt truncated for page length; source filing is linked above.]

Latest 10-K MD&A

Extracted structurally from real Item 7 body heading to real Item 7A/8 boundary. Confidence: high. Filing date: 2026-02-25. Report date: 2025-12-31.

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

You should read the following discussion and analysis of our financial condition and results of operations together with our consolidated financial statements and related notes included elsewhere in this Annual Report on Form 10-K. This discussion contains forward-looking statements that involve risks and uncertainties, including those described in the section titled “Special Note Regarding Forward Looking Statements.” Our actual results and the timing of selected events could differ materially from those discussed below. Factors that could cause or contribute to such differences include, but are not limited to, those identified below and those set forth under the section titled “Risk Factors” included elsewhere in this report.

Overview

We are a clinical-stage biotechnology company developing therapies for neurodegenerative diseases, with a focus on areas of high unmet medical need. Our work is informed by advances in disease biology, including the roles of misfolded or deficient proteins, lysosomal dysfunction, and immune and neuronal pathway disruption.

Our objective is to develop product candidates that address disease through targeted mechanisms, such as removing pathogenic proteins, replacing deficient proteins, and restoring normal cellular function. We are advancing a portfolio of programs focused on genetically validated targets, supported by our experience in drug development, protein engineering, and antibody discovery.

A key component of our strategy is the development and application of our Alector Brain Carrier (ABC) platform, a proprietary blood-brain barrier (BBB) delivery technology designed to improve central nervous system exposure across multiple therapeutic modalities. We continue to refine and expand this platform to enable effective brain delivery at clinically practical doses of antibodies, enzymes, and siRNA therapeutics. In parallel, we are investing in biomarkers and biomarker assays to guide patient selection, demonstrate target and pathway

94

engagement, and assess biological impact in the clinic, with the goal of improving development efficiency and the likelihood of technical success.

Our portfolio includes nivisnebart (formerly AL101/GSK4527226), an investigational PGRN-elevating antibody that has completed enrollment in a placebo-controlled, double-blinded Phase 2 study in early Alzheimer’s disease under our July 2021 Collaboration and License Agreement (GSK Agreement) with Glaxo Wellcome UK Limited, a subsidiary of GlaxoSmithKline plc (GSK).

In addition, our wholly owned programs include lead candidates in preclinical development for a brain-penetrant anti-amyloid beta antibody for Alzheimer’s disease (AD) and a brain-penetrant GCase enzyme replacement therapy for Parkinson’s disease (PD). We are also advancing brain-penetrant siRNA programs targeting tau for Alzheimer’s disease, α-synuclein for Parkinson’s disease, and NLRP3, with potential applications across multiple neurodegenerative conditions.

Our operations have been financed primarily through our collaboration with GSK, our previous collaboration with AbbVie, entered into in October 2017 and terminated in February 2025, the issuance and sale of convertible preferred stock and of common stock upon the completion of our initial public offering (IPO), and follow-on equity financings.

To date, we have not had any products approved for sale and have not generated any product or royalty revenue from product sales. Further, we do not expect to generate revenue from product sales until such time, if ever, that we are able to successfully complete the development and obtain marketing approval for one of our product candidates. We will continue to require additional capital to develop our product candidates, advance our research and preclinical programs, and fund operations for the foreseeable future. We have incurred net losses in each year since inception, and we expect to continue to incur net losses for the foreseeable future. Our ability to generate product revenue will depend on the successful development and eventual commercialization of one or more of our product candidates. Our net losses were $142.9 million and $119.0 million for the years ended December 31, 2025 and 2024, respectively. As of December 31, 2025, we had an accumulated deficit of $972.1 million. Substantially all of our net losses have resulted from costs incurred in connection with our research and development programs and from general and administrative costs associated with our operations. We expect our expenses will increase substantially in connection with our ongoing activities, as we:

•
advance product candidates through preclinical studies and clinical trials;

•
pursue regulatory approval of product candidates;

•
discover, validate, and develop additional product candidates;

•
require the manufacture of drug supply for our research, preclinical studies and clinical trials; and

•
obtain, maintain, and protect our intellectual property portfolio.

On March 7, 2025, we committed to a plan to reduce our workforce by approximately 13% to better align our resources with our strategic priorities including advancing our preclinical and research pipeline. We initiated such reduction in force impacting approximately 25 employees across the organization. On October 21, 2025, we initiated a reduce in force that impacted approximately 47% our workforce in order to align resources with the Company’s strategic priorities following the results of the Phase 3 INFRONT-3 clinical trial evaluating the safety and efficacy of latozinemab in individuals with frontotemporal dementia due to a progranulin gene mutation (FTD-GRN). As of December 31, 2025, we had cash, cash equivalents, and marketable securities of $256.0 million, which we anticipate provides runway at least through 2027.

Components of Results of Operations

Revenue

We have not generated any product or royalty revenue from product sales and do not expect to do so in the near future. Our revenue to date has been primarily related to the AbbVie Agreement and GSK Agreement for the license and co-development of product candidates with those parties. We recognized revenue from the upfront payments and the milestone payment received from AbbVie over time as services were provided. We recognize revenue from the upfront payments from GSK at a point in time for a development license and over time for research and development services. Revenues for research and development services are recognized as the program

95

costs are incurred by measuring actual costs incurred to date compared to the overall total expected costs to satisfy the performance obligation.

Under the terms of the GSK Agreement, we received $700 million in upfront payments, of which $500 million was received in August 2021 and $200 million was received in January 2022. In addition, we may be eligible to receive up to an additional $1.5 billion in clinical development, regulatory, and commercial launch-related milestone payments, subject to successful advancement and commercialization of product candidates in multiple indications under the agreement. Alector and GSK are conducting development jointly. Under the current terms of the GSK Agreement, we are responsible for funding GSK’s and our development costs up to $140.5 million for the conduct of the initial Phase 2 clinical trial of nivisnebart in AD.

In the United States, Alector and GSK agreed to equally share profits and losses from commercialization of product candidates under the agreement. We may opt out of the sharing of development costs and of profit and losses from commercialization in the United States on a product-by-product basis. In such case, we will no longer conduct development or commercialization of that product, we will receive royalties on net sales of the product in the United States instead of a share of profits, and certain milestones will be reduced. Outside of the United States, GSK agreed to responsible for commercialization of latozinemab and nivisnebart for all indications, and we will be eligible for double-digit tiered royalties.

We expect that our revenue for the next several years will be derived primarily from the GSK Agreement. The balance of deferred revenue was $171.2 million as of December 31, 2025, related to the GSK Agreement. The deferred revenue is expected to be recognized over the research and development period of the programs through the completion of the initial Phase 2 clinical trials for specified indications for latozinemab and nivisnebart.

Research and Development Expenses

Research and development expenses account for a significant portion of our operating expenses. We record research and development expenses as incurred. Research and development expenses consist primarily of costs incurred for the discovery and development of our product candidates, which include:

•
expenses incurred under agreements with third-party contract organizations, preclinical testing organizations, and consultants;

•
costs related to production of research, preclinical, and clinical materials, including fees paid to contract manufacturers;

•
laboratory and vendor expenses related to the execution of research, preclinical studies and clinical trials;

•
personnel-related expenses, including salaries, benefits, and stock-based compensation for personnel engaged in research and development functions;

•
costs related to the preparation of regulatory submissions;

•
third-party license fees; and

•
facilities and other expenses, which include expenses for rent and maintenance of facilities, depreciation and amortization expense, and other supplies.

We expense all research and development costs in the periods in which they are incurred. Costs for certain development activities are recognized based on an evaluation of the progress to completion of specific tasks using information and data provided to us by our vendors, collaborators, and third-party service providers. Nonrefundable advance payments for goods or services to be received in future periods for use in research and development activities are deferred and capitalized. The capitalized amounts are then expensed as the related goods are delivered and as services are performed.

Specific program expenses include expenses associated with the development of our most advanced product candidate, nivisnebart, which is being studied in the PROGRESS-AD Phase 2 clinical trial. We also have expenses related to the research and development of future product candidates and separately tracked expenses related to programs that we expect to move out of preclinical studies and into Phase 1 clinical trials. These expenses primarily relate to salaries and benefits, stock-based compensation, facility expenses, including depreciation, and lab consumables.

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Where we share costs with our collaboration partners, such as in our GSK Agreement, research and development expenses may include reimbursements from, or payments to, our partner.

At this time, we cannot reasonably estimate or know the nature, timing, and estimated costs of the efforts that will be necessary to complete the development of, and obtain regulatory approval for, any of our product candidates. We expect our research and development expenses relating to latozinemab and AL002 to decrease in the foreseeable future as a result of the discontinuation and wind-down of clinical trials for latozinemab and AL002. However, we continue to invest in research and development activities related to programs in our research and preclinical pipeline and to the advancement of those programs into clinical trials.

General and Administrative Expenses

General and administrative expenses consist primarily of personnel-related costs, including stock-based compensation, for our personnel in executive, legal, finance and accounting, information technology, human resources, and other administrative functions. General and administrative expenses also include legal fees relating to intellectual property and corporate matters, professional fees paid for accounting, auditing, consulting, and tax services, insurance costs, and facility costs not otherwise included in research and development expenses.

Other Income, Net

Other income, net consists primarily of interest earned on our cash equivalents and marketable securities.

Income Tax Expense

Income tax expense consists of federal and state income tax provisions.

Results of Operations

The following table sets forth selected consolidated statements of operations data for the fiscal years indicated and the percentage change in such data from year to year. These historical operating results may not be indicative of the results for any future period.

Comparison of the Years Ended December 31, 2025 and 2024

Year Ended

December 31,

Dollar

2025

2024

Change

(In thousands)

Collaboration revenue

$

21,045

$

100,558

$

(79,513

)

Operating expenses:

Research and development

123,065

185,940

(62,875

)

General and administrative

53,987

59,615

(5,628

)

Total operating expenses

177,052

245,555

(68,503

)

Loss from operations

(156,007

)

(144,997

)

(11,010

)

Other income, net

13,246

26,076

(12,830

)

Loss before income taxes

(142,761

)

(118,921

)

(23,840

)

Income tax expense

168

128

40

Net loss

$

(142,929

)

$

(119,049

)

$

(23,880

)

Revenue

Collaboration revenue was $21.0 million for the year ended December 31, 2025, compared to $100.6 million for the year ended December 31, 2024. The decrease of $79.6 million in revenue was primarily due to the satisfaction of the performance obligations associated with the AL002 program and the latozinemab FTD-C9orf72 Phase 2 trial in the fourth quarter of 2024, resulting in lower revenue recognized in 2025. Revenues are recognized as the program costs are incurred by measuring actual costs incurred to date compared to the overall total expected costs to satisfy the performance obligation.

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Research and Development Expenses

Research and development expenses were $123.1 million for the year ended December 31, 2025, compared to $185.9 million for the year ended December 31, 2024. The decrease of $62.8 million was mainly due to a decrease in research and development expenses for the AL002 program as well as a decrease in personnel related costs as a result of the reductions in force.

Year Ended

December 31,

Dollar

2025

2024

Change

(In thousands)

Direct research and development expenses

Latozinemab

$

14,824

$

13,909

$

915

Nivisnebart

6,418

4,656

1,762

AL002

6,429

50,222

(43,793

)

Other programs

20,204

16,908

3,296

Indirect research and development expenses

Personnel related (including stock-based

   compensation)

52,256

75,909

(23,653

)

Facilities and other unallocated research and

   development expenses

22,934

24,336

(1,402

)

Total research and development expenses

$

123,065

$

185,940

$

(62,875

)

General and Administrative Expenses

General and administrative expenses were $54.0 million for the year ended December 31, 2025, compared to $59.6 million for the year ended December 31, 2024. The decrease of $5.6 million was mainly due to a decrease in personnel related costs as a result of the reductions in force.

Other Income, Net

Other income, net was $13.2 million for the year ended December 31, 2025, compared to $26.1 million for the year ended December 31, 2024. The decrease of $12.9 million was due to lower interest income from a reduction in marketable securities used to fund our operations.

Income Tax Expense

Income tax expense was $0.2 million for the year ended December 31, 2025, compared to $0.1 million for the year ended December 31, 2024.

Liquidity and Capital Resources

Since our inception through December 31, 2025, our operations have been financed primarily by our collaborations with AbbVie and GSK and the issuance and sale of convertible preferred stock and of common stock upon the completion of our IPO and follow-on equity and debt financings.

As of December 31, 2025, we had $256.0 million of cash, cash equivalents, and marketable securities. As of December 31, 2025, we had an accumulated deficit of $972.1 million.

Future Funding Requirements

Our primary uses of cash are to fund our operations, which consist primarily of research and development expenditures related to our programs, and to a lesser extent, general and administrative expenditures. We expect our expenses to continue to increase in connection with our ongoing activities, in particular as we continue to advance our product candidates and our discovery and research programs. In addition, we expect to incur additional costs associated with operating as a public company.

As of December 31, 2025, we had cash, cash equivalents, and marketable securities of $256.0 million, which we anticipate provides runway at least through 2027. We reduced our workforce to better align our resources with

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our current strategic priorities and maintain our expectations with respect to our ability to fund our operations. We have based this estimate on assumptions that may prove to be wrong, and we could utilize our available capital resources sooner than we currently expect. We may also choose to seek additional financing opportunistically. We may seek to raise capital through public equity or debt financings, license agreements, collaborative agreements or other arrangements with other companies, asset sales, or through other sources of financing. We have an omnibus shelf registration statement on Form S-3 with the SEC, which became effective on May 1, 2023, which permits us to issue up to $400 million in common stock, other equity securities and/or debt securities. We will need to obtain substantial additional funding in the future for our research and development activities and continuing operations. If we are unable to raise capital when needed or on favorable terms, we would be forced to delay, reduce, or eliminate our research and development programs or future commercialization efforts.

On November 7, 2023, we entered into an at-the-market sales agreement with TD Securities (USA) LLC (TD Securities, formerly known as Cowen and Company, LLC) pursuant to which we may offer and sell from time to time through TD Securities up to $125,000,000 of shares of our common stock, in such share amounts as we may specify by notice to TD Securities (the Sales Agreement). As of December 31, 2025, we have issued 7,110,162 shares and received approximately $20.0 million in net proceeds from the sale of securities pursuant to the Sales Agreement. On January 17, 2024, we entered into an underwriting agreement with Cantor Fitzgerald & Co. (Cantor), pursuant to which we offered and sold 10,869,566 shares of the Company’s common stock at a price per share of $6.57 paid by Cantor. Additionally, on November 14, 2024, we entered into a loan agreement with our subsidiary, Alector LLC, as a co-borrower, the Lenders, and Hercules Capital, Inc., in its capacity as administrative agent and collateral agent for itself and the Lenders (the Loan Agreement), pursuant to which we may access up to two tranches of Term Loans in an aggregate principal amount of up to $50,000,000. The initial tranche of Term Loans provides for an aggregate principal amount of up to $25,000,000 through June 30, 2026, subject to the satisfaction of certain conditions. The second tranche of Term Loans provides for up to $25,000,000 and is available at the sole discretion of the Lenders. We borrowed $10,000,000 principal amount of the initial tranche of Term Loans on the closing date of the Loan Agreement.

We will need to obtain substantial additional funding in the future for our research and development activities and continuing operations. If we are unable to raise capital when needed or on favorable terms, we would be forced to delay, reduce, or eliminate our research and development programs or future commercialization efforts.

Our future capital requirements will depend on many factors, including:

•
the timing and progress of preclinical and clinical development activities; including, without limitation, our collaboration efforts with GSK;

•
the number and scope of preclinical and clinical programs we decide to pursue;

•
successful enrollment in and completion of clinical trials;

•
our ability to establish agreements with third-party manufacturers for clinical supply for our clinical trials and, if our product candidates are approved, commercial manufacturing;

•
the timing and progress of our current research and development programs and our ability to establish new research and development programs;

•
addition or retention of key research and development personnel;

•
our efforts to maintain or enhance operational, financial, and information management systems, and hire or retain personnel, including personnel to support development of our product candidates;

•
the costs associated with workforce reductions;

•
negotiating favorable terms in any collaboration, licensing, or other arrangements into which we may enter and performing our obligations in such collaborations;

•
the timing and amount of milestone and other payments we may receive under our collaboration arrangements;

•
the costs and timing of regulatory approvals;

•
our eventual commercialization plans for our product candidates;

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•
the effects of macroeconomic conditions, including inflationary pressures and economic impacts of tariffs and global trade disruptions; and

•
the costs involved in prosecuting, defending, and enforcing patent claims and other intellectual property claims.

A change in the outcome of any of these or other variables with respect to the development of any of our product candidates could significantly change the costs and timing associated with the development of that product candidate. Furthermore, our operating plans may change in the future, and we may need additional funds to meet operational needs and capital requirements associated with such operating plans.

Cash Flows

The following table summarizes our cash flows for the periods indicated (in thousands):

Year Ended

 December 31,

2025

2024

Cash used in operating activities

$

(184,031

)

$

(229,905

)

Cash provided by investing activities

196,597

107,131

Cash provided by financing activities

20,215

81,540

Operating Activities

For the year ended December 31, 2025, cash used in operating activities was $184.0 million. This was mainly due to the net loss of $142.9 million. We also had a decrease in deferred revenue of $21.0 million and a decrease in refund liability of $50.0 million. This was offset by a non-cash charge of $26.7 million for stock-based compensation.

For the year ended December 31, 2024, cash used in operating activities was $230.0 million. This was mainly due to the net loss of $119.0 million. We also had a decrease in deferred revenue of $100.6 million and a decrease in refund liability of $46.0 million. This was offset by a non-cash charge of $39.5 million for stock-based compensation.

Investing Activities

For the year ended December 31, 2025, cash provided by investing activities of $196.6 million was primarily related to the maturities of marketable securities of $465.5 million offset by purchases of marketable securities of $271.9 million.

For the year ended December 31, 2024, cash provided by investing activities of $107.1 million was primarily related to the maturities of marketable securities of $573.6 million offset by purchases of marketable securities of $467.7 million.

Financing Activities

For the year ended December 31, 2025, cash provided by financing activities of $20.2 million was primarily from the proceeds from the sale of securities pursuant to the sales agreement with TD Securities.

For the year ended December 31, 2024, cash provided by financing activities of $81.5 million was primarily from the issuance of common stock of $71.1 million upon a public offering and the debt issuance of $9.4 million.

Critical Accounting Policies and Estimates

Management’s discussion and analysis of our financial condition and results of operations is based on our consolidated financial statements, which have been prepared in accordance with generally accepted accounting principles in the United States (GAAP). 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 revenue generated and expenses incurred

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during the reporting periods. Our estimates are based on our 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 and any such differences may be material. We believe that the accounting policies discussed below are critical to understanding our historical and future performance, as these policies relate to the more significant areas involving management’s judgments and estimates.

Revenue Recognition

We recognize revenue when control of promised goods or services is transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. In determining the appropriate amount of revenue to be recognized as we fulfill our obligations under arrangements, we perform the following steps: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract, and (v) recognize revenue when (or as) the entity satisfies the performance obligations. If it is determined that multiple performance obligations exist, the transaction price is allocated at the inception of the agreement to all identified performance obligations based on the relative standalone selling price (SSP). The relative SSP for each deliverable is estimated using external sourced evidence if it is available. If external sourced evidence is not available, we use our best estimate of the SSP for the deliverable.

We recognize collaboration revenue at a point in time if control of the promised good or service has been transferred to the customer. We recognize collaboration revenue over time by measuring the progress toward complete satisfaction of the performance obligation using an input measure. In order to recognize revenue over the research and development period, we measure actual costs incurred to date compared to the overall total expected costs to satisfy the performance obligation. Revenues are recognized as the program costs are incurred. We re-evaluate the estimate of expected costs to satisfy the performance obligation each reporting period and make adjustments for any significant changes. Clinical trials are expensive and can take many years to complete, and the outcome is inherently uncertain. Changes in our forecasted costs are likely to occur over time based upon changes in clinical trial procedures set forth in protocols, changes in estimates of manufacturing costs, or feedback from regulators on the design or operation of our clinical trials. We have had changes to the overall expected costs to satisfy the performance obligations from period to period. For the year ended December 31, 2025, we recorded an $8.9 million increase to collaboration revenue under the GSK Agreement due to a decrease in total expected costs to satisfy the performance obligations for the nivisnebart program.

Accrued Research and Development Expenses

We record accrued expenses for estimated preclinical study and clinical trial expenses. Estimates are based on the services performed pursuant to contracts with research institutions, CROs in connection with clinical studies, investigative sites in connection with clinical studies, vendors in connection with preclinical development activities, and contract manufacturing organizations in connection with the production of materials for clinical trials. Further, we accrue expenses related to clinical trials based on the level of patient enrollment and activity according to the related agreement. We monitor patient enrollment levels and related activity to the extent reasonably possible and make judgments and estimates in determining the accrued balance in each reporting period. If we underestimate or overestimate the level of services performed or the costs of these services, our actual expenses could differ from our estimates. To date, we have not experienced significant changes in our estimates of preclinical studies and clinical trial accruals.