Alector Inc

The Company

Alector, Inc. (Alector or the Company) is a Delaware corporation headquartered in South San Francisco, California. Alector is a clinical stage biotechnology company pioneering immuno-neurology, a novel therapeutic approach for the treatment of neurodegeneration.

Summary of Significant Accounting Policies

Basis of Presentation

The consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States (GAAP)as defined by the Financial Accounting Standards Board (FASB). The consolidated financial statements include the accounts of Alector, Inc. and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expense during the reporting period. The Company evaluates its estimates, including those related to revenue recognition, manufacturing accruals, clinical accruals, fair value of assets and liabilities, income taxes uncertainties, stock-based compensation, and related assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could materially differ from those estimates.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents, and short-term marketable securities. Cash and cash equivalents are deposited in checking and sweep accounts at financial institutions. Such deposits may, at times, exceed federally insured limits.

Cash, Cash Equivalents, and Restricted Cash

The Company considers all highly liquid investments with original maturities of three months or less at the date of purchase to be cash and cash equivalents. Cash equivalents, which consist of amounts invested in money market funds, are stated at fair value.

Restricted cash relates to a letter of credit established for a lease entered into in June 2018.

The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the consolidated balance sheets that sum to the total of the same amounts shown in the consolidated statements of cash flows:

Marketable Securities

Allmarketable securities have been classified as “available-for-sale” and are carried at fair value, based upon quoted market prices. The Company considers its available-for-sale portfolio as available for use in current operations. Accordingly, the Company may classify certain investments as short-term marketable securities, even though the stated maturity date may be one year or more beyond the current balance sheet date. For available-for-sale debt securities, unrealized gains, net of any related tax effects, are excluded from earnings andare included in other comprehensive income and reported as a separate component of stockholders’ equity until realized. The Company assesses available-for-sale debt securities on a quarterly basis to see if any unrealized loss is due to credit-related factors. Factors considered in determining whether an impairment is credit-related include the extent to which the investment’s fair value is less than its cost basis, declines in published credit ratings, changes in interest rates, and any other adverse factors related to the security. If it is determined that a credit-related impairment exists, the Company will measure the credit loss based on a discounted cash flows model. Credit-related impairments on available-for-sale debt securities are recognized as an allowance for credit losses with a corresponding adjustment to other income, net in the Company’s consolidated statement of operations. The unrealized loss position that is not credit-related is recorded, net of any related tax effects, in other comprehensive income until realized. There wereno credit-related losses recognized for the periods presented.

The cost of securities sold is based on the specific-identification method. The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. In accordance with our investment policy, management invests in money market funds, U.S. treasury securities, corporate bonds, certificates of deposit, and commercial paper. The Company has not experienced any losses on its deposits of cash, cash equivalents, and marketable securities.

Fair Value of Financial Instruments

The Company’s financial instruments include cash and cash equivalents, marketable securities, receivable from collaboration partner, current and noncurrent prepaid expenses, accounts payable, and accrued liabilities. The Company’s financial instruments approximate fair value due to their relatively short maturities.

The Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible. The Company determines the fair value of its financial instruments based on assumptions that market participants would use in pricing an asset or liability in the principal or most advantageous market. When considering market participant assumptions in fair value measurements, the following fair value hierarchy distinguishes between observable and unobservable inputs, which are categorized in one of the following levels:

Level 1 – Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date;

Level 2 – Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and

Level 3 – Unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data.

Property and Equipment

Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation and amortization is computed using the straight-line method over the estimated useful lives of the respective assets, generally three tofive years. Leasehold improvements are amortized over the lesser of their useful lives or the remaining life of the lease. When assets are retired or otherwise disposed of, the cost and related accumulated depreciation and amortization are removed from the consolidated balance sheet and the resulting gain or loss is reflected in the consolidated statements of operations in the period realized. Maintenance and repairs are charged to the consolidated statements of operations as incurred.

Leases

The Company determines whether an arrangement is or contains a lease at the inception of the lease. Leases are recognized on the balance sheet as right-of-use assets and lease liabilities. Lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected lease term. The Company utilizes the appropriate incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. Certain adjustments to the right-of-use asset may be required for items such as initial direct costs paid or incentives received and any prepaid or accrued rent. Rent expense for the operating lease is recognized on a straight-line basis over the lease term and is included in operating expenses on the statements of operations and comprehensive loss. Variable lease payments include lease operating expenses.

The Company excludes balance sheet recognition of operating leases having a term of 12 months or less (short-term leases) and does not separate lease components and non-lease components for its long-term leases.

Impairment of Long-Lived Assets

The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparing the carrying amount to the future net undiscounted cash flows which the assets are expected to generate. If the total of the undiscounted future cash flows is less than the carrying amount of the assets, an impairment loss is recognized for the amount by which the carrying amount of the assets exceeds its fair value. For the years ended December 31, 2023 and 2022, the Company didnot recognize an impairment loss on its long-lived assets.

The Company recognizes 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 the Company fulfills its obligations under arrangements, the Company performs 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 obligation. 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 performance obligation 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 performance obligation.

The Company recognizes collaboration revenue at a point in time if control of the promised good or service has been transferred to the customer. The Company recognizes 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, the Company measures 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. The Company re-evaluates the estimate of expected costs to satisfy the performance obligation each reporting period.

Research and Development Costs

Research and development costs are expensed as incurred and consist primarily of new product development. Research and development costs include salaries and benefits, consultants’ fees, process development costs, stock-based compensation, and laboratory supplies, as well as fees paid to third parties that conduct certain research and development activities on the Company’s behalf. In addition, research and development costs include the reimbursable costs incurred for the collaboration agreements, which includes payroll costs for time incurred on projects, laboratory supplies, and third-party research and development activities.

Asubstantial portion of the Company’s ongoing research and development activities are conducted by third-party service providers. The Company records 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, the Company accrues expenses related to clinical trials based on the level of patient enrollment and activity according to the related agreement. The Company monitors 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 the Company underestimates or overestimates the level of services performed or the costs of these services, actual expenses could differ from estimates. To date, the Company has not experienced significant changes in its estimates of preclinical studies and clinical trial accruals.

Stock-based Compensation

Stock-based compensation is measured on the grant date based on the fair value of the awards. The fair value of options to purchase common stock is measured using the Black-Scholes option-pricing model. Stock-based compensation associated with restricted stock units (RSUs) is based on the fair value of the Company’s common stock on the grant date, which equals the closing price of the Company’s common stock on the grant date. The Company recognizes expense over the vesting period of the awards. Expense for options and RSUs that vest based only on a service condition is recognized on a straight-line basis.

The fair value of RSUs with market conditions is estimated using a Monte Carlo simulation model. Assumptions and estimates utilized in the model include the stock price on grant date, risk-free interest rate, dividend yield, expected stock volatility, and estimated period to achieve the market condition. The expense is recognized based on continued employment of the participants, regardless of achievement of the market condition. Expense related to the RSUs with market conditions is recognized using the accelerated attribution method.

The Company accounts for forfeitures as they occur for all awards.

Comprehensive Loss

Comprehensive loss includes net loss and certain changes in stockholders’ equity that are the result of transactions and economic events other than those with stockholders. The Company’s only element of other comprehensive loss was net unrealized gain (loss) on marketable securities.

Income Taxes

The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial statement and tax bases of assets and liabilities and are measured using enacted tax rates and laws that will be in effect when the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date.

The deferred tax assets are recognized to the extent the Company believes that these assets are more likely than not to be realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. Due to the Company’s historical operating performance and the recorded cumulative net losses in prior periods, the net deferred tax assets have been fully offset by a valuation allowance.

The Company records uncertain tax positions using a two-step process. First, the Company determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position. Second, for those tax positions that meet the more-likely-than-not recognition threshold, the Company recognizes the largest amount of tax benefit that is more than 50% likely to be realized upon ultimate settlement with the related tax authority.

The Company recognizes interest and penalties related to unrecognized tax benefits within the provision for taxes in the consolidated statements of operations. The Company accrued $0.2 million interest and penalties for the year ended December 31, 2023.

Employee 401(k) Plan

The Company has a qualified contributory savings plan under Section 401(k) of the Internal Revenue Code (the Code) covering substantially all U.S. employees of Alector. The 401(k) plan is designed to provide tax-deferred retirement benefits in accordance with the provisions of Section 401(k) of the Code. Eligible employees may defer up to 100% of their eligible compensation up to the annual maximum as determined by the Internal Revenue Service. The Company’s contributions to the plan are discretionary. For the years ended December 31, 2023, 2022, and 2021, the Company made matching contributions of $1.1 million, $1.2 million, and $0.8 million, respectively.

Segments

The Company operates in one segment. The Company’s chief operating decision maker, its Chief Executive Officer, manages the Company’s operations on a consolidated basis for purposes of allocating resources.

Recent Accounting Pronouncements

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which expands disclosures in an entity’s income tax rate reconciliation table and disclosures regarding cash taxes paid both in the U.S. and foreign jurisdictions. The update will be effective for annual periods beginning after December 15, 2024. The Company is currently evaluating the impact that this guidance will have on the Company’s consolidated financial statements and disclosures.

Fair Value Measurements

The following tables summarize the Company’s financial assets measured at fair value on a recurring basis by level within the fair value hierarchy:

The Company’s Level 2 securities are valued using third-party pricing sources. The pricing services utilize industry standard valuation models for which all significant inputs are observable. The Company classifies marketable securities available to fund current operations as current assets. As of December 31, 2023, the remaining contractual maturities of $503.1 million of investments were less than one year and $41.1 millionof investment were after one year through two years. The Company does not intend to sell the investments that are currently in an unrealized loss position, and it is highly unlikely that the Company will be required to sell the investments before recovery of their amortized cost basis, which may be at maturity. For the year ended December 31, 2023 and 2021, the Company sold marketable securities for the total proceeds of $3.5 million and $10.7 million for an immaterial realized loss and gain based on the specific identification method. The Company did not sell any marketable securities for the years ended December 31, 2022.

4. Commitments and Contingencies

Contingencies

From time to time, the Company may be involved in litigation related to claims that arise in the ordinary course of its business activities. The Company accrues for these matters when it is probable that future expenditures will be made and these expenditures can be reasonably estimated. As of December 31, 2023, the Company does not believe that any such matters, individually or in the aggregate, will have a material adverse effect on the Company’s financial position, results of operations or cash flows.

Indemnification

The Company enters into customary indemnification arrangements in the ordinary course of business with vendors, clinical trial sites and other parties. Pursuant to these arrangements, the Company indemnifies, holds harmless and agrees to reimburse the indemnified parties for certain losses suffered or incurred by the indemnified party. The term of these indemnification agreements is generally perpetual any time after the execution of the agreement. The maximum potential amount of future payments the Company could be required to make under these arrangements is not determinable. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification agreements. As a result, the Company hasnot recorded a liability related to such indemnification agreements as of December 31, 2023. As permitted under Delaware law, the Company has entered into indemnification agreements with its directors and officers that requires it to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers to the fullest extent permitted by law. The Company also has directors’ and officers’ insurance.

5. Collaboration Agreements

GSK

On July 1, 2021, the Company entered into a Collaboration and License Agreement with Glaxo Wellcome UK Limited, a subsidiary of GlaxoSmithKline plc (GSK), pursuant to which the Company and GSK collaborate on the global development and commercialization of progranulin-elevating monoclonal antibodies, including latozinemab, and AL101 (GSK Agreement). The GSK Agreement became effective on August 17, 2021.

Under the terms of the GSK Agreement, the Company 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, based on the development and commercialization plan for latozinemab and AL101, the Company may be eligible to receive up to an additional $1.5 billion in clinical development, regulatory, and commercial launch-related milestone payments. In the United States, the Company and GSK will equally share profits and losses from commercialization of latozinemab and AL101. Outside of the United States, the Company will be eligible for double-digit tiered royalties.

The Company and GSK will jointly develop latozinemab and AL101, with GSK conducting Phase 3 clinical trials for Alzheimer’s disease, Parkinson’s disease and other non-orphan indications. GSK will also conduct the initial Phase 2 trial for AL101 in Alzheimer’s disease. Development costs will be shared 60% by GSK and 40% by the Company, except that subject to the GSK Amendment (defined below), the Company will solely bear the development costs of the initial Phase 2 clinical trials under the development plan, and the parties will share manufacturing development costs equally.

In May 2023, the Company and GSK amended the GSK Agreement (GSK Amendment). Under the terms of the GSK Amendment, the Company is responsible for funding and sharing in GSK’s and the Company’s development costs up to $140.5 millionfor the conduct of the initial Phase 2 trial for AL101 in Alzheimer’s disease. The Company assessed the GSK Amendment in accordance with ASC 606 and concluded that the GSK Amendment was a contract modification to the GSK Agreement. Accordingly, the transaction price as of May 2023, was updated from $700 million to $571.6 million and the difference of $128.4 million was recorded as refund liability to collaboration partner for the expected cost reimbursement to GSK. The refund liability is an estimate of variable consideration calculated as the difference between the Company’s maximum funding of $140.5 million and the Company’s cost budget estimated using the expected value method. The Company determined that the modified performance obligation for the AL101 Alzheimer’s disease program is performing development activities to support the initial Phase 2 trial, including license rights and know-how. The Company updated the cost-based input measure of progress for the modified performance obligation and recorded a cumulative catch-up adjustment to revenue of $26.9 million on the modification date relating to the performance obligation which was satisfied in prior periods.

During the three months ended September 30, 2023, as a result of the planned closure of the latozinemab Phase 2 trial and concurrent agreement by the Company to cost-share additional R&D, the Company determined there was a modification of the GSK Agreement, resulting in a decrease of the scope of the performance obligation associated with the latozinemab FTD-C9orf72 Phase 2 trial and an increase in the amount of R&D cost-shared by the Company in future periods. The impact of this additional cost share was accounted for as a refund liability, which reduced the transaction price for the GSK Agreement by $4.2 million. The refund liability is an estimate of variable consideration. The Company determined that the modified performance obligation for the latozinemab FTD-C9orf72 indication is performing the first Phase 2 development activities, including license rights and know-how. The Company updated the cost-based input measure of progress for the modified performance obligation and recorded a cumulative catch-up adjustment to revenue of $4.9 million on the modification date relating to the performance obligation that was satisfied in prior periods.

The Company concluded that the GSK Agreement is within the scope of ASC 808, Collaborative Arrangements, as both parties are active participants in the activities and are exposed to significant risks and rewards dependent on the success of the commercialization of latozinemab and AL101. Certain elements are required to be accounted for under ASC 606, Revenue From Contracts With Customers, where the counterparty is a customer for a good or service that is a distinct unit of account.

The Company determined that the distinct performance obligations under ASC 606 consisted of: (i) license and know-how to latozinemab FTD-GRN, which is currently in Phase 3 clinical development and (ii) the research and development activities, including license rights and know-how, relating to products in Phase 2 or earlier stages of development.

The transaction price at inception included fixed consideration consisting of the upfront payments of $700 million. The transaction price as of December 31, 2023 was decreased to $569.0 million due to the estimated refund liabilities created from the contract modifications. The Company reassessed the estimated refund liabilities to collaboration partner as of December 31, 2023 to be $106.5 million. All potential future milestones and other payments were considered constrained at the inception of the GSK Agreement and as of December 31, 2023, since the Company could not conclude it was probable that a significant reversal in the amount of revenue recognized would not occur.

The respective standalone value for each of the performance obligations was allocated to the transaction price. The estimated SSP of each performance obligation was determined using discounted cash flows from the expected commercialization of latozinemab and AL101 and estimated research and development costs to be incurred by the Company in each of the initial Phase 2 clinical trials. The estimate of SSP for each performance obligation reflects management’s assumptions, which may include forecasted revenues, development timelines, discount rates, and probabilities of technical and regulatory success. For the license for FTD-GRN, the Company determined that GSK could benefit from the license at the time the license was granted and therefore, the related performance obligation was satisfied at a point in time. For the product candidates in Phase 2 or earlier stages of development, the Company determined that GSK could not benefit from the licenses without the corresponding development services that the Company has committed to perform due the earlier stage of development for these licenses. Except where agreed to otherwise, the Company will perform research and development activities through the end of the initial Phase 2 clinical trials. Revenue will be recognized over time as the research and development activities are performed. The

Company will measure progress based on actual costs incurred to date compared to the overall total expected costs to satisfy the performance obligations.

The research and development activities for products in Phase 3 clinical development were determined to be within the scope of ASC 808. Both parties will be active participants in the development, manufacturing, and commercialization of the product and are exposed to significant risks and rewards that are dependent on the commercial success of the products. The Company and GSK participate in profit and loss sharing for each program commensurate with each party’s cost-sharing responsibilities during research and development. ASC 808 does not provide recognition and measurement guidance. As such, the Company determined that ASC 730, Research and Development, was appropriate to analogize to based on the nature of the cost-sharing provision of the agreement. The Company has concluded that payments to or reimbursements from GSK related to these services will be accounted for as an increase to or reduction of research and development expenses, respectively.

Collaboration revenue under the GSK Agreement during the year ended December 31, 2023 and 2022, was $66.6 million and $62.9 million, respectively, the entire amount of which was included in deferred revenue at the beginning of the period. The deferred revenue related to the GSK Agreement was $247.4 million and $444.9 million as of December 31, 2023 and 2022. The deferred revenue is expected to be recognized over the research and development period of the programs through the completion of initial Phase 2 clinical trials.

Costs associated with co-development activities performed under the agreement are included in research and development expenses in the consolidated statements of operations, with any reimbursement of costs by GSK reflected as a reduction of such expenses. For the year ended December 31, 2023 and 2022, the Company recognized a reduction of research and development expense of $21.8 million and $14.7 million, respectively, under the GSK Agreement.

AbbVie

The Company entered into an agreement in October 2017 with AbbVie Biotechnology, Ltd. (AbbVie) to co-develop antibodies to two program targets in preclinical development (AbbVie Agreement). Under the terms of the AbbVie Agreement, AbbVie made $205.0 million in upfront payments, of which $5.0 million and $200.0 million were received by the Company in October 2017 and January 2018, respectively. The Company was to perform research and development services for the two programs through the end of Phase 2 clinical trials, which were each considered to be separate performance obligations. AbbVie decided to terminate one of the two collaboration programs, the CD33 collaboration program, after AbbVie and Alector concluded that further development of AL003, the asset being developed under that program, was not warranted. AbbVie provided written notice to terminate the CD33 collaboration program on June 30, 2022. Accordingly, the Company is no longer developing that program and will not be eligible for any future milestones related to that program from AbbVie. The Company continues to develop the AL002 program under the AbbVie Agreement. AbbVie has the exclusive right to exercise an option under the AbbVie Agreement with the Company for $250.0 million. If AbbVie exercises its option for the AL002 program, AbbVie would take over development of the product candidate, and the program costs will be split between the parties. The Company would also share in profits and losses upon commercialization of any products. Alternatively, following AbbVie’s exercise of its option for the AL002 program, the Company may opt out of sharing in development costs and profits or losses for that program and instead receive tiered royalties. Additionally, under the terms of the AbbVie Agreement, the Company will be eligible to earn up to an additional $225.0 million in milestone payments related to the regulatory approval for up to three indications. The Company assessed its collaboration agreement with AbbVie in the context of the delivery of the research and development services.

In February 2023, the Company and AbbVie amended the AbbVie Agreement (AbbVie Amendment), which resulted in the Company receiving a $17.8 million milestone payment in March 2023 for the dosing of the first patient in a long-term extension (LTE) trial. In addition, under the terms of the AbbVie Amendment, the Company was eligible to earn up to an additional $12.5 million to support the enrollment of additional patients to replace discontinuations. The performance obligations to conduct the LTE trial and enroll additional patients are not considered distinct from the AL002 program performance obligation. The Company received $5.7 million related to the enrollment of additional patients from AbbVie in the third quarter of 2023 and received the remaining $6.8 million in the fourth quarter of 2023. The transaction price as of December 31,

2023 included fixed consideration consisting of the upfront payments of $205.0 million, the $17.8 million LTE milestone payment, and the $12.5 million payment for enrollment of additional patients.

Collaboration revenue under the AbbVie Agreement during the years ended December 31, 2023 was $30.5 million, $10.9 million of which was included in deferred revenue at the beginning of the period. Collaboration revenue under the AbbVie Agreement during the years ended December 31, 2022 and 2021 was $70.7 million and $14.9 million, respectively. The deferred revenue related to the AbbVie Agreement was $46.4 million and $46.7 million as of December 31, 2023 and 2022, respectively. The deferred revenue is expected to be recognized over the research and development period of the AL002 program through the completion of the ongoing Phase 2 and the Phase 2 LTE clinical trials.

6. Balance Sheet Components

Property and Equipment, Net

Property and equipment, net consists of the following:

Accrued Liabilities

Accrued liabilities consist of the following:

7. Leases

In June 2018, the Company signed a lease agreement to lease approximately 105,000 square feet in office and laboratory space in South San Francisco which serves as the Company’s headquarters (the Headquarters). The lease expires in 2029 with an option to renew for a period often years. The landlord paid for $15.7 million of tenant improvements. In connection with the lease, the Company entered into a letter of credit arrangement in the amount of $1.5 million as collateral for the lease, which is classified as restricted cash on the consolidated balance sheets. In October 2020, the Company signed a lease agreement to lease approximately 18,700 square feet of office and laboratory space in Newark, California. The lease term ends on February 6, 2028 with an option to extend for an additional five years. The landlord is obligated to pay for up to $0.4 million of tenant improvements. Themeasurement of the lease liabilities for the leases excludes the options to extend the term ofthe lease as such extensions are not reasonably certain to occur. Variable lease costs for all of the Company’s leases consist of operating expenses for the spaces.

In May 2019, the Company entered into an agreement to sublease approximately 25,000 square feet of the Headquarters, which was amended to approximately 23,600 square feet in December 2020. This Sublease expired in November 2021.

In November 2021, the Company entered into an agreement to sublease approximately 7,100 square feet of the Headquarters, which was amended in May 2022 to include an additional space of 13,150 square feet. The 7,100 square feet of space subleased expired in December 2022 and the additional space of 13,150 expired in November 2023. In October 2023, the Company entered into a second amendment to sublease approximately 13,250 square feet of the Headquarters. This sublease will expire in November 2024.

In February 2023, the Company entered into an agreement to sublease approximately 9,300 square feet of the Headquarters. This sublease will expire in February 2025. The sublessee pays its proportionate share of operating expenses for the space.

The components of lease expense were as follows:

As of December 31, 2023, the weighted-average remaining lease term for operating leases was 5.2 years and the weighted-average discount rate was 8.5%. Cash paid for amounts included in the measurement of lease liabilities for the year ended December 31, 2023, 2022, and 2021 was $8.4 million, $8.2 million, and $7.9 million, respectively, was included in net cash used in operating activities in our consolidated statements of cash flows.

The following are the lease payments owed under the Company’s operating leases as of December 31, 2023:

8. Stock-based Compensation

The Company recognized stock-based compensation as follows (in thousands):

Determination of Fair Value

The estimated grant-date fair value of all the Company’s options to purchase common stock was calculated using the Black-Scholes option pricing model, based on the following assumptions:

The fair value of each stock option was determined by the Company using the methods and assumptions discussed below. Each of these inputs is subjective and generally requires judgment and estimation by management.

Expected Term—The expected term represents the period that stock-based awards are expected to be outstanding. The expected term was derived by using the simplified method which uses the midpoint between the average vesting term and the contractual expiration period of the stock-based award.

Expected Volatility—The Company has limited information on the volatility of stock options as the shares were not actively traded on any public markets prior to February 7, 2019. The expected volatility was derived from the historical stock volatilities of comparable peer public companies within its industry. These companies are considered to be comparable to the Company’s business over a period equivalent to the expected term of the stock-based awards. In 2020, the Company began giving weight to in its own historical volatility in the determination of expected volatility.

Risk-Free Interest Rate—The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the date of grant for zero-coupon U.S. Treasury notes with maturities approximately equal to the expected term.

Expected Dividend Rate—The expected dividend is zero as the Company has not paid nor does it anticipate paying any dividends on its common stock in the foreseeable future.

2019 Equity Incentive Plan and 2022 Inducement Plan

On February 6, 2019, the Company adopted the 2019 Equity Incentive Plan (2019 Plan) under which the Board may issue incentive stock options, nonstatutory stock options, restricted stock, restricted stock units, stock appreciation rights, performance units, and performance shares to the Company’s employees, directors, and consultants. The Company’s 2017 Stock Option and Grant Plan (2017 Plan) was terminated; however, shares subject to awards granted under it will continue to be governed by the 2017 Plan. Shares reserved for issuance but not issued pursuant to, or not subject to, awards granted under the 2017 Plan were added to the available shares in the 2019 Plan. Shares subject to awards granted under the 2017 Plan that are repurchased by, or forfeited to, the Company will also be reserved for issuance under the 2019 Plan. The board of directors, or a committee appointed by the board of directors, has the authority to determine to whom options orshares will be granted, the number of shares, the term, and the exercise price. If an individual owns stock representing 10% or more of the outstanding shares, the exercise price of each share shall be at least 110% of the fair market value and the term of the award shall not exceed five years. All other options granted under the 2019 Plan must have an exercise price at least equal to the fair market value on the date of grant and have a term not to exceedten years. The stock options generally vest over afour-year period with one forty-eighth of the shares vesting each month or over a four-year period with 25% vesting at theone-year cliff and monthly thereafter. The RSUs generally vest over a period of three years with one-twelfth of the shares vesting quarterly.

On January 1, 2023, the Company added 4,144,785 shares to the shares reserved for issuance under the 2019 Equity Incentive Plan. As of December 31, 2023, the Company had reserved 23,018,705 shares of common stock under the 2019 Plan, of which 6,579,341 shares were available for issuance of future awards.

On January 1, 2022, the Company adopted the 2022 Inducement Plan (Inducement Plan) and reserved 1,630,000 shares for issuance under the Inducement Plan for the grant of equity-based awards to individuals who were not previously employees or non-employee directors of the Company. On September 22, 2022, the Company increased the number of shares available for issuance under the 2022 Inducement Plan to a total of 3,300,000 shares. As of December 31, 2023,1,407,389 shares were available for issuance of future awards under the Inducement Plan.

Option activity is shown below:

The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying stock options and the fair value of the Company’s common stock for stock options that were in-the-money. The aggregate intrinsic value of options exercised was less than $0.1 million, $1.2 million, and $37.1 million for the years ended December 31, 2023, 2022, and 2021, respectively. The weighted-average grant-date fair value per share of options granted was $4.93, $8.42, and $14.70, for the years ended December 31, 2023, 2022, and 2021, respectively. As of December 31, 2023, total unrecognized stock-based compensation related to unvested stock options was $32.7 million, which the Company expects to recognize over a remaining weighted-average period of 2.1 years.

Restricted Stock Unit Activity

Activity for the RSUs is shown below. In May 2021 and January 2022, the Company issued RSUs with market conditions to certain executives, which are also included in the table below. The RSUs with market conditions are earned based on stock price performance and continued service by the employee. The RSUs with market conditions trigger vesting upon the Company’s stock price attaining a specified level over a specified period of time. The shares then vest quarterly over one year after attainment. The Company used a Monte Carlo simulation model to determine the fair value of the awards at the grant date. The Monte Carlo model uses the fair value inputs on the grant date to run simulations and take an average of possible outcomes. The total grant date fair value of the RSUs with market condition was $6.6 million to be amortized over an estimated weighted average service period of 2.1 years. Compensation expense related to awards with market-based conditions is recognized regardless of whether the market condition is ultimately satisfied if the related service has been provided.

As of December 31, 2023, total unrecognized stock-based compensation related to unvested restricted common stock issued to employees was $41.5 million, which the Company expects to recognize over a remaining weighted-average period of 2.3 years.

2019 Employee Stock Purchase Plan

The 2019 Employee Stock Purchase Plan (2019 ESPP) enables eligible employees of the Company to purchase shares of common stock at a discount. Each offering period is approximatelysix months long beginning on the first trading day on or after June 1 and December 1 each year. ESPP participants purchase shares of common stock at a price per share equal to 85% of the lesser of (1) the fair market value per share of the common stock on the first trading day of the offering period or (2) the fair market value of the common stock on the purchase date. On January 1, 2023,591,397 shares were added to the shares reserved for issuance under the 2019 ESPP pursuant to the annual automatic increase. As of December 31, 2023, there was $0.4 million in unrecognized compensation expense related to the 2019 ESPP expected to be recognized over five months.

9. Income Taxes

The federal and state income tax provision for the year ended December 31, 2023, 2022 and 2021 are summarized as follows (in thousands):

A reconciliation of the federal statutory rate to the Company’s effective tax rate is as follows for the years ended December 31, 2023, 2022, and 2021 (in thousands):

The tax effects of temporary differences that give rise to significant components of the Company’s deferred tax assets and liabilities consist of (in thousands):

In assessing the realization of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred assets will be realized. The ultimate realization of the deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Evaluating the need for a valuation allowance for deferred tax assets often requires judgment and analysis of all the positive and negative evidence available, including cumulative losses in recent years and projected future taxable income, to determine whether all or some portion of the deferred tax assets will not be realized. As of December 31, 2023, the Company has utilized a full valuation allowance to offset the net deferred tax assets as the Company believes it is not more likely than not that the net deferred tax assets will be fully realizable. The valuation allowance for deferred tax assets increased by $40.2 million during the year ended December 31, 2023.

As of December 31, 2023, the Company had federal and state net operating loss (NOL) carryforwards of approximately zero and $202.2 million, respectively. Federal NOL carryforwards have an indefinite life and deductions cannot exceed 80% of taxable income. State NOL carryforwards will begin to expire as early as

2030, if not utilized, or have an indefinite life. As of December 31, 2023, the Company also had federal and California tax credit carryforward of approximately $27.1 million and $19.3 million, respectively. The federal tax credits will begin to expire in 2041 while the California tax credits have no expiration date.

Generally, utilization of the NOL carryforwards and credits may be subject to an annual limitation due to the ownership change limitations provided by Section 382, which provides for limitations on NOL carryforwards and certain built-in losses following ownership changes, and Section 383, which provides for special limitations on certain excess credits, etc., of the Code, and similar state provisions. Accordingly, the Company’s ability to utilize NOL carryforwards may be limited as the result of such an “ownership change.” The carryforwards could be subject to an annual limitation, resulting in a reduction in the gross deferred tax assets before considering the valuation allowance. Further, a portion of the carryforwards may expire before being applied to reduce future earnings. The Company is not aware of any changes in ownership that would result in material limitations under Section 382 at this time.

The following table summarizes the activity related to the Company’s unrecognized tax benefits for the years ended December 31, 2023, 2022, and 2021 (in thousands):

If the unrecognized tax benefits for uncertain tax positions as of December 31, 2023, is recognized, there will be no impact to the effective tax rate as the tax benefit would increase the net deferred tax assets, which is currently offset with a full valuation allowance. The Company’s policy is to include interest and penalties related to unrecognized tax benefits, if any, within the provision for taxes in the consolidated statements of operations. The Company accrued $0.2 million interest and penalties for the year ended December 31, 2023. The Company does not have any tax positions for which it is reasonably possible that the total amount of gross unrecognized tax benefits will significantly change within 12 months of December 31, 2023.

The Company recognizes the tax benefit of an uncertain tax position only if it is more likely than not that the position is sustainable upon examination by the taxing authority, based on the technical merits. During the years ended December 31, 2023 and 2022, the Company recorded an uncertain tax position of $5.1 million and $8.2 million, respectively. The income tax provision for the years ended December 31, 2023, included changes to reserves related to prior year uncertain tax provisions of an increase of $2.6 million and decrease of $0.6 million. The income tax provision for the years ended December 31, 2022, included changes to reserves ofzero. The Company’s income tax returns generally remain subject to examination by federal and most state tax authorities. The Company is currently not subject to any income tax audits by federal or state taxing authorities. The statute of limitations for tax liabilities for all years remains open.

10. Related Party Transactions

In 2014, the Company entered into a collaboration agreement with Adimab, LLC (Adimab) under which the Company is developing antibodies discovered by Adimab in its latozinemab and AL101 programs and is developing antibodies optimized by Adimab in its AL002 program (2014 Adimab Agreement). The 2014 Adimab Agreement also provided for the Company’s development of antibodies optimized by Adimab in its AL003 program, which was terminated in June 2022. In August 2019, the Company signed a collaboration agreement with Adimab for research and development of additional antibodies, the term of which was extended effective August 2022 (2019 Adimab Agreement). In December 2021, the Company signed another collaboration agreement with Adimab for antibody engineering research programs (2021 Adimab Agreement). The 2021 Adimab Agreement expired and the Company did not exercise any option to carry forward any of the results. Tillman Gerngross, Ph.D, the Executive Chairman of the board of directors of Adimab is a co-founder and former director of Alector. Dr. Gerngross resigned as a member of the Company’s board of directors, effective June 15, 2023. For the years ended December 31, 2023, the Company didnot incur any expenses related to Adimab. For the years ended December 31, 2022, and 2021, the Company incurred expenses of $0.2 million, and $1.0 million, respectively. The Company hadno accrued liabilities due to Adimab as of December 31, 2023 and 2022. Under the 2014 Adimab Agreement, the Company has made milestone payments and will owe low- to mid- single-digit royalty payments for commercial sales of the product candidate. Under the 2019 Adimab Agreement, the Company will owe certain milestone payments and low single-digit royalty payments for commercial sales of any covered product candidates.

11. Net Loss Per Share

The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share for the periods presented due to their anti-dilutive effect:

12. Restructuring

On March 28, 2023, the Company committed to a plan to reduce its workforce by approximately 11% to better align the Company’s resources with its previously announced strategic prioritization of its late-stage progranulin and TREM2 immuno-neurology programs. The Company initiated a reduction in force impacting approximately 30 employees across the organization effective March 29, 2023. For the year ended December 31, 2023, the Company incurred restructuring costs of approximately $1.7 million, primarily consisting of one-time charges related to the reduction in force, including personnel expenses such as salaries, one-time severance payments, and other benefits, which were included in operating expenses. Accrued liabilities associated with restructuring costs were $0.1 million as of December 31, 2023.

13. Subsequent Events

On January 17, 2024, the Company entered into an underwriting agreement with Cantor Fitzgerald & Co. (Cantor), relating to the issuance and sale of 10,869,566 shares of the Company’s common stock at a price per share of $6.57 paid by Cantor. The Company also granted Cantor an option exercisable for 30 days from the date of the underwriting agreement to purchase up to an additional 1,630,434 shares of common stock. Aggregate gross proceeds from the offering were approximately $75.0 million before deducting $3.9 million for underwriting discounts and commissions and estimated offering expenses payable by the Company. The offering closed on January 19, 2024. The option to purchase additional shares was not exercised by Cantor.