ALECTOR, INC.

131 OYSTER POINT BOULEVARD, SUITE 600

SOUTH SAN FRANCISCO, CA 94080

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

To Be Held at 8:00 a.m. Pacific Time on Wednesday, June 14, 2023

Dear Stockholders of Alector, Inc.:

We cordially invite you to attend the 2023 annual meeting of stockholders (the “Annual Meeting”) of Alector, Inc., a Delaware corporation (“Alector” or the “Company”), which will be held on Wednesday, June 14, 2023 at 8:00 a.m. Pacific Time. The Annual Meeting will be held virtually via a live webcast at https://web.lumiagm.com/209804434 password: alector2023 (cap sensitive), originating from South San Francisco, California, for the following purposes, as more fully described in the accompanying proxy statement:

1. To elect three Class II directors to serve until the 2026 annual meeting of stockholders and until their successors are duly elected and qualified;

2. To ratify the appointment of Ernst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2023;

3. To conduct an advisory vote to approve the compensation of our named executive officers; and

4. To transact such other business that may properly come before the Annual Meeting or any adjournments or postponements thereof.

Our Board of Directors has fixed the close of business on April 17, 2023 as the record date for the Annual Meeting. Only stockholders of record on April 17, 2023 are entitled to notice of and to vote at the Annual Meeting. Further information regarding voting rights and the matters to be voted upon is presented in the accompanying proxy statement.

On or about April 27, 2023, we expect to mail to our stockholders a Notice of Internet Availability of Proxy Materials (the “Notice”) containing instructions on how to access our proxy statement and annual report. The Notice provides instructions on how to vote via the Internet or by telephone and how to receive a paper copy of our proxy materials by mail. The accompanying proxy statement and our annual report can be accessed directly at the following Internet address: http://www.astproxyportal.com/ast/22640. All you have to do is enter the control number located on your Notice or proxy card.

YOUR VOTE IS IMPORTANT. Whether or not you plan to attend the Annual Meeting, we urge you to submit your vote via the Internet, telephone, or mail as soon as possible.

We appreciate your continued support of Alector.

By order of the Board of Directors,

Arnon Rosenthal, Ph.D.

Co-founder, Chief Executive Officer, and Director

South San Francisco, California

April 27, 2023

TABLE OF CONTENTS

ALECTOR, INC.

PROXY STATEMENT

FOR THE 2023 ANNUAL MEETING OF STOCKHOLDERS

To Be Held at 8:00 a.m. Pacific Time on Wednesday, June 14, 2023

This proxy statement and the enclosed form of proxy are furnished in connection with the solicitation of proxies by our Board of Directors for use at the 2023 annual meeting of stockholders of Alector, Inc., a Delaware corporation, and any postponements, adjournments, or continuations thereof (the “Annual Meeting”). The Annual Meeting will be held virtually, via live webcast at https://web.lumiagm.com/209804434 password: alector2023 (cap sensitive), originating from South San Francisco, California. The Notice of Internet Availability of Proxy Materials (the “Notice”) containing instructions on how to access this proxy statement and our annual report is first being mailed on or about April 27, 2023 to all stockholders entitled to vote at the Annual Meeting.

The information provided in the “question and answer” format below is for your convenience only and is merely a summary of the information contained in this proxy statement. You should read this entire proxy statement carefully. Information contained on, or that can be accessed through, our website is not intended to be incorporated by reference into this proxy statement and references to our website address in this proxy statement are inactive textual references only.

QUESTIONS AND ANSWERS ABOUT THE PROXY MATERIALS

AND OUR ANNUAL MEETING

Why are you holding a virtual Annual Meeting?

This year’s Annual Meeting will be a “virtual meeting” of stockholders. We are continuously exploring technologies and services that will best permit our stockholders to engage with us and vote. We have implemented the virtual format in order to facilitate stockholder attendance at our Annual Meeting. We have designed our virtual format to enhance, rather than constrain, stockholder access, participation, and communication. For example, the virtual format allows stockholders to communicate with us in advance of, and during, the Annual Meeting so they can ask questions of our Board of Directors or management.

How do I attend and participate in the Annual Meeting online?

We will be hosting the meeting via live webcast only at https://web.lumiagm.com/209804434 password: alector2023 (cap sensitive). You will be able to submit your questions and vote your shares electronically during the Annual Meeting.

The webcast will start at 8:00 a.m. Pacific Time. You are encouraged to access the meeting prior to the start time. The webcast will open 15 minutes before the start of the meeting, and you should allow ample time for the check-in procedures. In order to enter the meeting, you will need the control number. The control number will be included in the Notice or on your proxy card if you are a stockholder of record of shares of common stock (as defined below) or included with your voting instructions received from your broker, bank, or other financial intermediary if you hold your shares of common stock in a “street name.” Instructions on how to attend and participate online are available at https://web.lumiagm.com/209804434 password: alector2023 (cap sensitive).

How can I get help if I have trouble checking in or listening to the meeting online?

If you encounter any difficulties accessing the virtual meeting during the check-in or meeting time, please call the technical support number that will be posted on the log-in page.

- 1 -

What matters am I voting on?

You will be voting on:

How does the Board of Directors recommend I vote on these proposals?

Our Board of Directors recommends a vote:

Who is entitled to vote?

Holders of our common stock as of the close of business on April 17, 2023, the record date for the Annual Meeting, may vote at the Annual Meeting. As of the record date, there were 83,351,778 shares of our common stock outstanding. In deciding all matters at the Annual Meeting, each stockholder will be entitled to one vote for each share of our common stock held by them on the record date. We do not have cumulative voting rights for the election of directors.

Registered Stockholders. If shares of our common stock are registered directly in your name with our transfer agent, you are considered the stockholder of record with respect to those shares, and the Notice was provided to you directly by us. As the stockholder of record, you have the right to grant your voting proxy directly to the individuals listed on the proxy card or vote on your own behalf at our Annual Meeting. Throughout this proxy statement, we refer to these registered stockholders as “stockholders of record.”

Street Name Stockholders. If shares of our common stock are held on your behalf in a brokerage account or by a broker, bank, or other nominee, you are considered to be the beneficial owner of shares that are held in “street name,” and the Notice was forwarded to you by your broker, bank, or other nominee, who is considered the stockholder of record with respect to those shares. As the beneficial owner, you have the right to direct your broker, bank, or other nominee as to how to vote your shares. Beneficial owners are also invited to attend our Annual Meeting. However, since a beneficial owner is not the stockholder of record, you may not vote your shares of our common stock on your own behalf at the Annual Meeting unless you follow your broker’s procedures for obtaining a legal proxy. If you request a printed copy of our proxy materials by mail, your broker, bank, or other nominee will provide a voting instruction form for you to use. Throughout this proxy statement, we refer to stockholders who hold their shares through a broker, bank, or other nominee as “street name stockholders.”

How many votes are needed for approval of each proposal?

- 2 -

What is the quorum?

A quorum is the minimum number of shares required to be present at the Annual Meeting for the Annual Meeting to be properly held under our bylaws and Delaware law. The presence (including by proxy) of a majority of all issued and outstanding shares of our common stock entitled to vote at the Annual Meeting will constitute a quorum at the Annual Meeting. Abstentions, withhold votes, and broker non-votes are counted as shares present and entitled to vote for purposes of determining a quorum.

How do I vote?

If you are a stockholder of record, there are four ways to vote:

Even if you plan to participate in our Annual Meeting, we recommend that you also vote by proxy so that your vote will be counted if you later decide not to participate in the Annual Meeting.

If you are a street name stockholder, you will receive voting instructions from your broker, bank, or other nominee. You must follow the voting instructions provided by your broker, bank, or other nominee in order to instruct your broker, bank, or other nominee on how to vote your shares. Street name stockholders should generally be able to vote by returning an instruction card, by telephone, or on the Internet. However, the availability of telephone and Internet voting will depend on the voting process of your broker, bank, or other nominee. As discussed above, if you are a street name stockholder, you may not vote your shares on your own behalf at the Annual Meeting unless you obtain a legal proxy from your broker, bank, or other nominee.

- 3 -

Can I change my vote?

Yes. If you are a stockholder of record, you can change your vote or revoke your proxy any time before the Annual Meeting by:

If you are a street name stockholder, your broker, bank, or other nominee can provide you with instructions on how to change your vote.

You may also change your vote or revoke your proxy by attending our Annual Meeting and voting online during the meeting. Simply attending the meeting will not, by itself, revoke your proxy.

What is the effect of giving a proxy?

Proxies are solicited by and on behalf of our Board of Directors. Arnon Rosenthal, Ph.D. and Sara Kenkare-Mitra, Ph.D. have been designated as proxy holders by our Board of Directors. When proxies are properly dated, executed, and returned, the shares represented by such proxies will be voted at the Annual Meeting in accordance with the instructions of the stockholder. If no specific instructions are given, however, the shares will be voted in accordance with the recommendations of our Board of Directors as described above. If any matters not described in this proxy statement are properly presented at the Annual Meeting, the proxy holders will use their own judgment to determine how to vote the shares. If the Annual Meeting is adjourned, the proxy holders can vote the shares on the new Annual Meeting date as well, unless you have properly revoked your proxy instructions, as described above.

Why did I receive a Notice of Internet Availability of Proxy Materials instead of a full set of proxy materials?

In accordance with the rules of the Securities and Exchange Commission (“SEC”), we have elected to furnish our proxy materials, including this proxy statement and our annual report, primarily via the Internet. The Notice containing instructions on how to access our proxy materials is first being mailed on or about April 27, 2023 to all stockholders entitled to vote at the Annual Meeting. Stockholders may request to receive all future proxy materials in printed form by mail or electronically by e-mail by following the instructions contained in the Notice. We encourage stockholders to take advantage of the availability of our proxy materials on the Internet to help reduce the environmental impact and cost of our annual meetings of stockholders.

How are proxies solicited for the Annual Meeting?

Our Board of Directors is soliciting proxies for use at the Annual Meeting. All expenses associated with this solicitation will be borne by us. We will reimburse brokers or other nominees for reasonable expenses that they incur in sending our proxy materials to you if a broker, bank, or other nominee holds shares of our common stock on your behalf. In addition, our directors and employees may also solicit proxies in person, by telephone, or by other means of communication. Our directors and employees will not be paid any additional compensation for soliciting proxies.

How may my brokerage firm or other intermediary vote my shares if I fail to provide timely directions?

Brokerage firms and other intermediaries holding shares of our common stock in street name for their customers are generally required to vote such shares in the manner directed by their customers. In the absence of timely

- 4 -

directions, your broker will have discretion to vote your shares on our sole “routine” matter: the proposal to ratify the appointment of Ernst & Young LLP as our independent registered public accounting firm. Your broker will not have discretion to vote on the election of directors, or on the approval, on an advisory basis, of the compensation of our named executive officers, which are “non-routine” matters, absent direction from you.

Where can I find the voting results of the Annual Meeting?

We expect to announce voting results at the Annual Meeting. We will also disclose voting results on a Current Report on Form 8-K that we will file with the SEC within four business days after the Annual Meeting.

I share an address with another stockholder, and we received only one paper copy of the proxy materials. How may I obtain an additional copy of the proxy materials?

We have adopted a procedure called “householding,” which the SEC has approved. Under this procedure, we deliver a single copy of the Notice and, if applicable, our proxy materials, to multiple stockholders who share the same address unless we have received contrary instructions from one or more of the stockholders. This procedure reduces our printing costs, mailing costs, and fees. Stockholders who participate in householding will continue to be able to access and receive separate proxy cards. Upon written or oral request, we will deliver promptly a separate copy of the Notice and, if applicable, our proxy materials, to any stockholder at a shared address to which we delivered a single copy of any of these materials. To receive a separate copy, or, if a stockholder is receiving multiple copies, to request that we only send a single copy of the Notice and, if applicable, our proxy materials, such stockholder may contact us at the following address:

Alector, Inc.

Attention: Investor Relations

131 Oyster Point Boulevard, Suite 600

South San Francisco, California 94080

Tel: (415) 231-5660

Street name stockholders may contact their broker, bank, or other nominee to request information about householding.

What is the deadline to propose actions for consideration at next year’s annual meeting of stockholders or to nominate individuals to serve as directors?

Stockholder Proposals

Stockholders may present proper proposals for inclusion in our proxy statement and for consideration at the next annual meeting of stockholders by submitting their proposals in writing to our Secretary in a timely manner. For a stockholder proposal to be considered for inclusion in our proxy statement for our 2024 annual meeting of stockholders, our Secretary must receive the written proposal at our principal executive offices not later than December 28, 2023. In addition, stockholder proposals must comply with the requirements of Rule 14a-8 regarding the inclusion of stockholder proposals in company-sponsored proxy materials. Stockholder proposals should be addressed to:

Alector, Inc.

Attention: Secretary

131 Oyster Point Boulevard, Suite 600

South San Francisco, California 94080

Tel: (415) 231-5660

Our bylaws also establish an advance notice procedure for stockholders who wish to present a proposal before an annual meeting of stockholders but do not intend for the proposal to be included in our proxy statement. Our

- 5 -

bylaws provide that the only business that may be conducted at an annual meeting of stockholders is business that is (i) specified in our proxy materials with respect to such meeting, (ii) otherwise properly brought before such meeting by or at the direction of our Board of Directors, or (iii) properly brought before such meeting by a stockholder of record entitled to vote at the annual meeting who has delivered timely written notice to our Secretary, which notice must contain the information specified in our bylaws. To be timely for our 2024 annual meeting of stockholders, our Secretary must receive the written notice at our principal executive offices:

In the event that we hold our 2024 annual meeting of stockholders more than 30 days before or more than 60 days after the one-year anniversary of the Annual Meeting, notice of a stockholder proposal that is not intended to be included in our proxy statement must be received no earlier than the close of business on the 120th day before our 2024 annual meeting of stockholders and no later than the close of business on the later of the following two dates:

If a stockholder who has notified us of his, her, or its intention to present a proposal at an annual meeting does not appear to present his, her, or its proposal at such annual meeting, we are not required to present the proposal for a vote at such annual meeting.

Nomination of Director Candidates

You may propose director candidates for consideration by our Corporate Governance and Nominating Committee. Any such recommendations should include the nominee’s name and qualifications for membership on our Board of Directors and should be directed to our Secretary at the address set forth above. For additional information regarding stockholder recommendations for director candidates, see “Board of Directors and Corporate Governance—Stockholder Recommendations for Nominations to the Board of Directors.”

In addition, our bylaws permit stockholders to nominate directors for election at an annual meeting of stockholders. To nominate a director, the stockholder must provide the information required by our bylaws. In addition, the stockholder must give timely notice to our Secretary in accordance with our bylaws, which, in general, require that the notice be received by our Secretary within the time periods described above under “Stockholder Proposals” for stockholder proposals that are not intended to be included in a proxy statement.

Availability of Bylaws

A copy of our amended and restated bylaws may be obtained by accessing our filings on the SEC’s website at www.sec.gov. You may also contact our Secretary at our principal executive offices for a copy of the relevant bylaw provisions regarding the requirements for making stockholder proposals and nominating director candidates.

- 6 -

BOARD OF DIRECTORS AND CORPORATE GOVERNANCE

Our business affairs are managed under the direction of our Board of Directors, which is currently composed of nine members. Six of our directors, Drs. Garofalo, Hammond, and Yaffe and Messrs. Lavigne, McGuire, and Wehner, are independent within the meaning of the listing standards of The Nasdaq Global Select Market (“Nasdaq”). Our Board of Directors is divided into three staggered classes of directors. At each annual meeting of stockholders, a class of directors will be elected for a three-year term to succeed the same class whose term is then expiring.

The following table sets forth the names and certain other information about each of the nominees for Class II director. The names of and certain other information about the continuing members of our Board of Directors are also set forth below. All information is as of March 31, 2023:

Nominees for Director

Elizabeth Garofalo, M.D. Dr. Garofalo has served as a member of our Board of Directors since September 2021. Since 2016, Dr. Garofalo has served as the Principal for EAG Pharma Consulting LLC. Prior to that, Dr. Garofalo served in numerous leadership roles including as Senior Vice President and Global Head of Clinical Development and member of the Novartis Global Development Leadership Team, Chair of the Novartis Portfolio Stewardship Board, and Co-Head of the Novartis Neuroscience Franchise. Prior to that, she was Vice President and Head of the Neuroscience Therapy Area at Astellas. She started her career at Parke-Davis/Pfizer where she had jobs of increasing responsibility, including Ann Arbor Site Head of Neuroscience and Ann Arbor Site Head of Worldwide Regulatory Affairs. Since September 2020, Dr. Garofalo has served as a member of the board of Acadia Pharmaceuticals Inc. Since March 2021, she has served as a member of the board and member of the audit committee of Exicure, Inc. and since March 2022, as chair of the board of Exicure, Inc. She has served since June 2021 as a member of the board of Xenon Pharmaceuticals. She also serves as the chair of the board of the non-profit Institute for Advanced Clinical Trials in Children. Dr. Garofalo earned an M.D. from the Indiana University School of Medicine where she completed her pediatric residency. She completed fellowships in pediatric neurology and epilepsy at the University of Michigan Medical School.

We believe Dr. Garofalo is qualified to serve on our Board of Directors because of her scientific background, including her clinical development experience, and her executive experience in the pharmaceutical industry.

- 7 -

Terry McGuire. Mr. McGuire has served as a member of our Board of Directors since 2013. Mr. McGuire is a co-founder and currently a general partner of Polaris Partners. Prior to starting Polaris Partners in 1996, Mr. McGuire spent seven years at Burr, Egan, Deleage & Co., investing in early stage medical and information technology companies. He currently serves on the board of directors of Invivyd, Inc. (formerly Adagio Therapeutics); Cycleron Therapeutics, Inc.; Seer, Inc; and several private companies. He previously served on the boards of Acceleron Pharma, Inc., Arsanis, Inc., Ironwood Pharmaceuticals, Inc., and Pulmatrix, Inc. Mr. McGuire is the former chairman of the National Venture Capital Association, which represents ninety percent of the venture capitalists in the U.S., former chairman of the board of the Thayer School of Engineering at Dartmouth College, and a member of the boards of The Arthur Rock Center for Entrepreneurship at Harvard Business School, The Healthcare Initiative Board at Harvard Business School, and the Scientific Advisory Board at Brigham Research Institute. Mr. McGuire earned a B.S. in physics and economics from Hobart College, an M.S. in engineering from The Thayer School at Dartmouth College, and an M.B.A. from Harvard Business School.

We believe Mr. McGuire is qualified to serve on our Board of Directors because of his expertise and experience in the biotechnology industry through his role as a Founding Partner of Polaris Partners and his cumulative career as a venture capitalist over a period spanning over 35 years, as well as his experience as a director of several biotechnology companies, including other public companies.

Kristine Yaffe, M.D. Dr. Yaffe has served as a member of our Board of Directors since August 2019. Dr. Yaffe is currently a professor of psychiatry, neurology, and epidemiology at the University of California, San Francisco (“UCSF”) and has served in that role since 2007. Dr. Yaffe has also served as the Roy and Marie Scola Endowed Chair since 2009 and Vice Chair in Psychiatry at UCSF since 2016. In addition to her roles at UCSF, Dr. Yaffe is the Chair of Neuropsychiatry and the Director of the Memory Disorders Clinic at the San Francisco Veterans Affairs Medical Center. She also currently serves on the Beeson Scientific Advisory Board and the Global Council on Brain Health. She previously served as the Co-Chair of the United States’ Institute of Medicine’s Committee on Cognitive Aging. Dr. Yaffe has received numerous awards for her groundbreaking contributions to the field including the American Academy of Neurology Potamkin Prize for Research in Pick’s, Alzheimer’s, and Related Diseases. Dr. Yaffe also received the American Association for Geriatric Psychiatry’s Distinguished Scientist Award. Dr. Yaffe holds a B.S. in biology-psychology from Yale University and an M.D. from the University of Pennsylvania School of Medicine and has completed residencies in neurology and psychiatry at UCSF. Dr. Yaffe was elected to the National Academy of Medicine in 2019.

We believe Dr. Yaffe is qualified to serve on our Board of Directors based on her experience as an internationally recognized expert in the fields of cognitive aging, neurodegeneration, and dementia.

Continuing Directors

Tillman Gerngross, Ph.D. Dr. Gerngross co-founded Alector in 2013 and has served as a member of our Board of Directors and as Chairperson since 2013. Effective June 13, 2023, Dr. Gerngross will step down as Chairperson of our Board of Directors, and, effective June 15, 2023, he will resign as a member of our Board of Directors. Dr. Gerngross is a founder, director, and executive officer of numerous biotechnology companies. He is a founder and currently serving as Executive Chairman of the board of directors of Adimab, LLC. He is also a founder and Chairman of the board of directors of Amagma, Inc. and Ankyra Therapeutics, Inc. Dr. Gerngross previously served on the board of directors of Adagio Therapeutics, Inc. from 2020 to 2022, Avitide, Inc. from 2012 to 2021, and Arsanis, Inc. from 2010 to 2019. Dr. Gerngross is currently a Venture Partner at SV Life Sciences Advisors, LLC, which he joined in 2006. Dr. Gerngross co-founded GlycoFi, Inc. and served as its Chief Scientific Officer from 2000 to 2006 until it was acquired by Merck & Company, Inc. Dr. Gerngross currently teaches at the School of Engineering at Dartmouth College, where he has taught since 1998. Dr. Gerngross attended the Technical University of Vienna, Austria, where he received a B.S. and M.S. in Chemical Engineering and a Ph.D. in Molecular Biology.

We believe Dr. Gerngross is qualified to serve on our Board of Directors because of the perspective and experience he provides as one of our founders, his expertise and experience in antibody drug discovery and

- 8 -

development, his experience as a founder and director of other life sciences companies, his educational background, and his experience working in the venture capital industry.

Louis J. Lavigne, Jr. Mr. Lavigne has served as a member of our Board of Directors and as our Lead Independent Director since October 2018. Effective June 13, 2023, Mr. Lavigne will serve as Chairperson of our Board of Directors and will no longer serve as our Lead Independent Director. Mr. Lavigne is Managing Partner of Laman Partners, LLC, a consulting firm focusing on finance, strategy, and management, since 2019 and Managing Director of Lavrite, LLC since 2005. Mr. Lavigne served in various executive capacities with Genentech, Inc. for over 20 years, including Chief Financial Officer from 1988 to 2005, Executive Vice President from 1997 to 2005, Senior Vice President from 1994 to 1997, Vice President from 1986 to 1994, and Controller from 1983 to 1986. He served as a member of the board of directors of Zynga Inc., a social game company, from 2015 to May 2022, including as an audit committee member (and formerly audit committee chairperson) and as a member of the nominating and governance committee. Mr. Lavigne was a member of the board of directors of Accuray, Inc., a radiation oncology company, between 2009 and June 2021, where he served as chairman of the board and the compensation committee as well as a member of the nominating and governance committee. He also served as a member of the board of directors of Rodan + Fields, LLC, a private skincare company, from June 2015 to July 2021 where he was lead director between August 2020 and July 2021 and chaired the audit committee from December 2019 to July 2021. Within the last five years, Mr. Lavigne also served as a director and chair of the audit committee of NovoCure Limited, an oncology company, from 2013 until October 2018; as a director, chair of the compensation committee, and member of the audit committee of Assertio Therapeutics, Inc., a pharmaceutical company, from July 2013 until his resignation in May 2019; and as a director, chair of the audit committee, and member of the compensation committee of DocuSign Inc., an eSignature transaction management company, from July 2013 to May 2020. Mr. Lavigne is the former chairman and board member of the UCSF Benioff Children’s Hospitals and the UCSF Benioff Children’s Hospitals Foundation. Mr. Lavigne holds a B.S. in Business Administration from Babson College and an M.B.A. from Temple University.

We believe Mr. Lavigne is qualified to serve on our Board of Directors because of his extensive experience in business operations and management, strategy, finance, accounting, and public company governance as a chief financial officer of a large, complex publicly-traded company and his extensive board leadership positions with a number of public company boards and board committees.

Richard H. Scheller, Ph.D. Dr. Scheller has served as a member of our Board of Directors since October 2018 and has served as co-chair of our Strategic Portfolio Advice and Review Committee (“SPARC”) since December 2019. Dr. Scheller has served as the Chairman of Research and Development at BridgeBio Pharma LLC, a publicly traded biotechnology company, since January 2019 and as a member of its board of directors since January 2018. Dr. Scheller previously served as Chief Scientific Officer at 23andMe, a personal genetics company, from April 2015 to April 2019. Previously, Dr. Scheller was the Executive Vice President of Research and Early Development and a member of the Executive Committee at Genentech, Inc. from February 2001 to December 2014. From January 2009 to December 2014, Dr. Scheller was also a member of the Enlarged Executive Committee at Hoffmann-La Roche Ltd. From February 2015 to June 2021, Dr. Scheller served as a member of the board of directors of ORIC Pharmaceuticals, Inc., and from March 2015 to 2019, Dr. Scheller served as a member of the board of directors of Xenon Pharmaceuticals Inc. Dr. Scheller’s research on elucidating the molecular machinery and regulatory mechanism that underlie the release of neurotransmitters earned him the 2013 Albert Lasker Basic Medical Research Award. He is a member of the National Academy of Sciences and a member of the National Academy of Medicine. Dr. Scheller holds a Ph.D. in Chemistry from the California Institute of Technology and B.Sc. in Biochemistry from the University of Wisconsin-Madison. He completed his post-doctorate in Biology at Caltech and his post-doctorate in Molecular Neurobiology at Columbia University.

We believe Dr. Scheller is qualified to serve on our Board of Directors because of his scientific background and his senior management experience in the pharmaceutical industry.

- 9 -

Arnon Rosenthal, Ph.D. Dr. Rosenthal co-founded Alector in 2013 and has served as a member of our Board of Directors and as Chief Executive Officer since 2013. Dr. Rosenthal co-founded Annexon Biosciences, Inc. and served as its acting Chief Executive Officer from August 2011 to December 2014 and served as a member of the board of directors, including as Chairman from August 2011 to February 2017. Dr. Rosenthal co-founded Rinat Neuroscience Corporation (acquired by Pfizer Inc. in August 2006), and served as President, Chief Scientific Officer, and as a member of the board of directors from August 2001 to August 2006. From January 1985 to August 2001, Dr. Rosenthal served in various roles at Genentech, Inc., where he ultimately served as Staff Scientist and was appointed as a permanent member of Genentech’s Research Review Committee, where his team discovered the target for the cancer drug Erivedge. Dr. Rosenthal conducted his post-doctoral fellowship at Genentech, Inc. He holds a Ph.D. in biology from the Hebrew University of Jerusalem.

We believe Dr. Rosenthal is qualified to serve on our Board of Directors because of the perspective and experience he provides as one of our founders and as our Chief Executive Officer, his experience as a founder and director of other life sciences companies, his educational background, as well as his broad experience within the pharmaceutical industry, particularly in the area of neuroscience and drug discovery and development.

Paula Hammond, Ph.D. Dr. Hammond has served as a member of our Board of Directors since March 2020. Dr. Hammond is the David H. Koch Chair Professor of Engineering at the Massachusetts Institute of Technology (“MIT”), where she has been a faculty member since 1995, and she has served as the Head of the Department of Chemical Engineering at MIT since 2016. She is a member of MIT’s David H. Koch Institute for Integrative Cancer Research and a founding member of the MIT Institute for Soldier Nanotechnology. She also served as the Associate Head of the Chemical Engineering Department at MIT from 2008 to 2011. Dr. Hammond was the recipient of the 2013 AIChE Charles M. A. Stine Award, which is bestowed annually to a leading researcher in recognition of outstanding contributions to the field of materials science and engineering, the 2014 Alpha Chi Sigma Award for Chemical Engineering Research, and the Margaret Rousseau Award for Lifetime Achievement by a Woman Chemical Engineer in 2019. She received the Department of Defense Ovarian Cancer Teal Innovator Award in 2013, which supports a single visionary individual from any field principally outside of ovarian cancer to focus his/her creativity, innovation, and leadership on ovarian cancer research. She was named a Fellow of the American Physical Society, the American Institute of Biological and Medical Engineering, and the American Chemical Society, Division of Polymer Chemistry. Dr. Hammond was elected into the National Academy of Sciences in 2019, the National Academy of Engineering in 2017, the National Academy of Medicine in 2016, and the 2013 Class of the American Academy of Arts and Sciences. Dr. Hammond holds an M.S. in Chemical Engineering from the Georgia Institute of Technology and a Ph.D. and S.B. in Chemical Engineering from MIT. Dr. Hammond has published over 330 papers and over 20 patent applications. She is the co-founder and member of the Scientific Advisory Board of LayerBio, Inc., a member of the board of directors of Advanced Chemotherapy Technologies, Inc., a member of the board of directors of Senda Biosciences, Inc., a member of the board of directors of the MIT Engine, a member of the Scientific Advisory Board of Moderna, Inc., and an advisor for Catalio Capital Management.

We believe Dr. Hammond is qualified to serve on our Board of Directors based on her scientific background and experience as an internationally recognized expert in the field of chemical engineering and based on her work in the field of cancer research.

David Wehner. Mr. Wehner has served as a member of our Board of Directors since October 2018. He has served as Chief Strategy Officer of Meta Platforms, Inc. (formerly Facebook, Inc.), a publicly-traded company, since November 2022. Mr. Wehner joined Meta Platforms, Inc. in November 2012 as Vice President, Corporate Finance and Business Planning and served as Chief Financial Officer from June 2014 to November 2022. From August 2010 until November 2012, Mr. Wehner served as Chief Financial Officer at Zynga Inc., a provider of social game services. From February 2001 to July 2010, Mr. Wehner served in various positions at Allen & Company, an investment bank, including as a Managing Director from November 2006 to July 2010 and as a director from December 2005 to November 2006. Mr. Wehner holds an M.S. in applied physics from Stanford University and a B.S. in chemistry from Georgetown University.

- 10 -

We believe Mr. Wehner is qualified to serve on our Board of Directors based on his substantial executive, strategy, finance, and operational experience.

Director Independence

Our common stock is listed on Nasdaq. Under the rules of Nasdaq, independent directors must comprise a majority of a listed company’s board of directors. In addition, the rules of Nasdaq require that, subject to specified exceptions, each member of a listed company’s audit, compensation, and corporate governance and nominating committees be independent. Audit committee members and compensation committee members must also satisfy the independence criteria set forth in Rule 10A-3 and Rule 10C-1, respectively, under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). Under the rules of Nasdaq, a director will only qualify as an “independent director” if, in the opinion of that company’s board of directors, that person does not have a relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director.

To be considered independent for purposes of Rule 10A-3 and under the rules of Nasdaq, a member of an audit committee of a listed company may not, other than in his or her capacity as a member of the audit committee, the board of directors, or any other board committee: (1) accept, directly or indirectly, any consulting, advisory, or other compensatory fee from the listed company or any of its subsidiaries or (2) be an affiliated person of the listed company or any of its subsidiaries.

To be considered independent for purposes of Rule 10C-1 and under the rules of Nasdaq, the board of directors must affirmatively determine that each member of the compensation committee is independent, including a consideration of all factors specifically relevant to determining whether the director has a relationship to the company which is material to that director’s ability to be independent from management in connection with the duties of a Compensation Committee member, including, but not limited to: (1) the source of compensation of such director, including any consulting, advisory, or other compensatory fee paid by the company to such director and (2) whether such director is affiliated with the company, a subsidiary of the company, or an affiliate of a subsidiary of the company.

Our Board of Directors undertook a review of its composition, the composition of its committees, and the independence of our directors and considered whether any director has a material relationship with us that could compromise his or her ability to exercise independent judgment in carrying out his or her responsibilities. Based upon information requested from and provided by each director concerning his or her background, employment, and affiliations, including family relationships, our Board of Directors has determined that Drs. Garofalo, Hammond, and Yaffe and Messrs. Lavigne, McGuire, and Wehner do not have a relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director and that each of these directors is “independent” as that term is defined under the rules of Nasdaq.

In making these determinations, our Board of Directors considered the current and prior relationships that each non-employee director has with our company and all other facts and circumstances our Board of Directors deemed relevant in determining their independence, including the beneficial ownership of our capital stock by each non-employee director, and the transactions involving them described in the section titled “Related Party Transactions.” There are no family relationships among any of our nominees for director, directors, or executive officers.

Lead Independent Director

Our Board of Directors appointed Louis J. Lavigne, Jr. to serve as our Lead Independent Director. As a general matter, our Board of Directors believes that appointing a Lead Independent Director, either when our Chief Executive Officer serves as Chairperson or when our Chairperson is not independent, creates an environment that encourages objective oversight of management’s performance and enhances the effectiveness of our Board of

- 11 -

Directors as a whole. As Lead Independent Director, Mr. Lavigne presides over periodic meetings of our independent directors, serves as a liaison between our Chairperson, Chief Executive Officer, and our independent directors, and performs such additional duties as our Board of Directors may otherwise determine and delegate. Effective upon Mr. Lavigne assuming the role of Chairperson of our Board of Directors, Mr. Lavigne will no longer serve as Lead Independent Director. Because Mr. Lavigne will be an independent Chairperson, we do not intend to appoint a new Lead Independent Director at this time.

Environmental, Social & Governance (ESG) Practices

We recognize that environmental, social, and governance (ESG) issues are of increasing importance to our investors, employees, and other stakeholders. We are committed to ethical, responsible, and sustainable business practices. Corporate social responsibility is an enterprise-wide commitment. Our management team and Board of Directors, including our Corporate Governance and Nominating Committee, are working together to oversee the Company’s efforts to prioritize and integrate ESG considerations into the Company’s business practices and corporate culture.

Board Diversity

The Corporate Governance and Nominating Committee is committed to continuing to identify and recruit highly qualified director candidates with diverse experiences, perspectives, and backgrounds to join our Board of Directors. The table below provides certain information regarding the composition of our Board of Directors. Each of the categories listed in the below table has the meaning as it is used in Nasdaq Rule 5605(f). As shown below in the board diversity matrix, the Company is currently in compliance with the diversity requirements of Nasdaq Rule 5605(f).

Role of the Board in Risk Oversight

Risk is inherent with every business, and we face a number of risks, including strategic, financial, business and operational, legal and compliance, and reputational. We have designed and implemented processes to manage risk in our operations. Management is responsible for the day-to-day management of risks that we face, while our Board of Directors, as a whole and assisted by its committees, has responsibility for the oversight of risk management. In its risk oversight role, our Board of Directors has the responsibility to satisfy itself that the risk management processes designed and implemented by management are appropriate and functioning as designed.

Our Board of Directors is responsible for general oversight of risks and regular review of information regarding our risks. The Audit Committee is responsible for overseeing the management of risks relating to accounting matters and financial reporting and potential conflicts of interest. The Compensation Committee is responsible for overseeing the management of risks relating to our executive compensation plans and arrangements. The Corporate Governance and Nominating Committee is responsible for overseeing the management of risks associated with the independence of our Board of Directors. Although each committee is responsible for evaluating certain risks and overseeing the management of such risks, our entire Board of Directors is regularly informed through discussions from committee members about such risks.

- 12 -

Our Board of Directors believes that open communication between management and our Board of Directors is essential for effective risk management and oversight. Our Board of Directors meets with our Chief Executive Officer and other members of the senior management team at the meetings of our Board of Directors, where, among other topics, they discuss strategy and risks facing us, as well as at such other times as they deemed appropriate. Our Board of Directors believes its administration of its risk oversight function has not negatively affected the Board of Directors’ leadership structure.

Executive Sessions of Independent Directors

In order to promote open discussion among independent directors, our Board of Directors has a policy of conducting executive sessions of independent directors on a periodic basis, and typically has such a session after each regularly scheduled board meeting. The Lead Independent Director or independent Chairperson is the presiding director over these executive sessions.

Board Meetings and Committees

During the fiscal year ended December 31, 2022, our Board of Directors held five meetings (including regularly scheduled and special meetings), and each director attended at least 75% of the aggregate of (i) the total number of meetings of our Board of Directors held during the period for which he or she has been a director and (ii) the total number of meetings held by all committees of our Board of Directors on which he or she served during the periods that he or she served. Although we do not have a formal policy regarding attendance by members of our Board of Directors at annual meetings of stockholders, we encourage our directors to attend. All but two of our directors attended our 2022 annual meeting of stockholders.

Our Board of Directors has established an Audit Committee, a Compensation Committee, and a Corporate Governance and Nominating Committee, each of which has the composition and the responsibilities described below.

Audit Committee

The members of our Audit Committee are Messrs. Lavigne and McGuire and Drs. Garofalo and Yaffe. Mr. Lavigne is the chairperson of our Audit Committee and our Audit Committee financial expert (“Financial Expert”), as that term is defined under the SEC rules implementing Section 407 of the Sarbanes-Oxley Act of 2002 (“SOX”), as he possesses financial sophistication, as defined under the rules of Nasdaq. Effective May 3, 2023, the members of our Audit Committee will be Messrs. Wehner, Lavigne, and McGuire, with Mr. Wehner serving as the chairperson of our Audit Committee. Additionally, effective May 3, 2023, Messrs. Lavigne and Wehner will serve as our Audit Committee Financial Experts.

Our Audit Committee oversees our corporate accounting and financial reporting process and assists our Board of Directors in monitoring our financial systems. The Company’s management is responsible for preparing our financial statements, and the independent auditor is responsible for auditing and reviewing those financial statements. The Audit Committee is responsible for assisting our Board of Directors in overseeing the conduct of these activities by management and the independent auditor. Our Audit Committee also:

- 13 -

Our Audit Committee operates under a written charter, which satisfies the applicable rules of the SEC and the listing standards of Nasdaq. A copy of the charter of our Audit Committee is available on our website at https://investors.alector.com. During the fiscal year ended December 31, 2022, our Audit Committee held four meetings.

Compensation Committee

The members of our Compensation Committee are Messrs. Wehner and Lavigne and Drs. Garofalo and Hammond. Mr. Wehner is the chairperson of our Compensation Committee. Effective May 3, 2023, the members of our Compensation Committee will be Drs. Garofalo and Hammond and Mr. Lavigne, with Dr. Garofalo serving as the chairperson of our Compensation Committee.

Our Compensation Committee oversees our compensation policies, plans, and benefits programs. The Compensation Committee also:

Our Compensation Committee operates under a written charter, which satisfies the applicable rules of the SEC and the listing standards of Nasdaq. A copy of the charter of our Compensation Committee is available on our website at https://investors.alector.com. During the fiscal year ended December 31, 2022, our Compensation Committee held five meetings.

Corporate Governance and Nominating Committee

The members of our Corporate Governance and Nominating Committee are Mr. McGuire and Drs. Hammond and Yaffe. Mr. McGuire is the chairperson of our Corporate Governance and Nominating Committee. Effective May 3, 2023, the members of our Corporate Governance and Nominating Committee will be Drs. Yaffe and Hammond and Mr. McGuire, with Dr. Yaffe serving as the chairperson of the Corporate Governance and Nominating Committee.

- 14 -

Our Corporate Governance and Nominating Committee oversees and assists our Board of Directors in reviewing and recommending nominees for election as directors. Specifically, the Corporate Governance and Nominating Committee:

Our Corporate Governance and Nominating Committee operates under a written charter, which satisfies the applicable rules of the SEC and the listing standards of Nasdaq. A copy of the charter of our Corporate Governance and Nominating Committee is available on our website at https://investors.alector.com. During the fiscal year ended December 31, 2022, our Corporate Governance and Nominating Committee held five meetings.

Compensation Committee Interlocks and Inside Participation

None of the members of our Compensation Committee is or has been an officer or employee of Alector. None of our executive officers currently serves, or in the past fiscal year has served, as a member of the board of directors or compensation committee (or other board committee performing equivalent functions or, in the absence of any such committee, the entire board of directors) of any entity that has one or more executive officers serving on our Board of Directors or Compensation Committee.

Considerations in Evaluating Director Nominees

Our Corporate Governance and Nominating Committee uses a variety of methods for identifying and evaluating director nominees. In its evaluation of director candidates, our Corporate Governance and Nominating Committee will consider the current size and composition of our Board of Directors and the needs of our Board of Directors and the respective committees of our Board of Directors. Some of the qualifications that our Corporate Governance and Nominating Committee considers include, without limitation, issues of character, integrity, judgment, diversity of experience, independence, area of expertise, corporate experience, length of service, potential conflicts of interest, and other commitments. Nominees must also have the ability to offer advice and guidance to management and be leaders in the companies or institutions with which they are affiliated. Director candidates must have sufficient time available in the judgment of our Corporate Governance and Nominating Committee to perform all board of director and committee responsibilities. Members of our Board of Directors are expected to prepare for, attend, and participate in all Board of Director and applicable committee meetings. Other than the foregoing, there are no stated minimum criteria for director nominees, although our Corporate Governance and Nominating Committee may also consider such other factors as it may deem, from time to time, are in our and our stockholders’ best interests.

Although our Board of Directors does not maintain a specific policy with respect to board diversity, our Board of Directors believes that our Board of Directors should be a diverse body, and our Corporate Governance and Nominating Committee may consider such factors as differences in professional background, education, skill, and other individual qualities and attributes that contribute to the total mix of viewpoints and experience represented on our Board of Directors. In making determinations regarding nominations of directors, our Corporate Governance and Nominating Committee may take into account the benefits of diverse viewpoints. Our

- 15 -

Corporate Governance and Nominating Committee also considers these and other factors as it oversees the annual board of director and committee evaluations. After completing its review and evaluation of director candidates, our Corporate Governance and Nominating Committee recommends to our full Board of Directors the director nominees for selection.

Stockholder Recommendations for Nominations to the Board of Directors

Our Corporate Governance and Nominating Committee will consider director candidates recommended by stockholders holding no less than $2,000 in market value, or 1%, of the outstanding shares of the Company’s common stock continuously for at least 12 months prior to the date of the submission of the recommendation, so long as such recommendations comply with our amended and restated certificate of incorporation and bylaws and applicable laws, rules, and regulations, including those promulgated by the SEC.

Our Corporate Governance and Nominating Committee will evaluate such recommendations in accordance with its charter, our bylaws, our policies and procedures for director candidates, as well as the regular director nominee criteria described above. Eligible stockholders wishing to recommend a candidate for nomination should contact our Secretary in writing. Such recommendations must include information about the candidate and any relationships between the candidate and our Company, a statement of support by the recommending stockholder, evidence of the recommending stockholder’s ownership of our common stock, and a signed letter from the candidate confirming willingness to serve on our Board of Directors. Our Corporate Governance and Nominating Committee has discretion to decide which individuals to recommend for nomination as directors.

Under our bylaws, stockholders may also directly nominate persons for our Board of Directors. Any nomination must comply with the requirements set forth in our amended and restated bylaws and should be sent in writing to our Secretary at Alector, Inc., 131 Oyster Point Boulevard, Suite 600, South San Francisco, California 94080. To be timely for our 2024 annual meeting of stockholders, our Secretary must receive the nomination no earlier than February 11, 2024 and no later than March 13, 2024.

Communications with the Board of Directors

Interested parties wishing to communicate with our Board of Directors or with an individual member or members of our Board of Directors may do so by writing to our Board of Directors or to the particular member or members of our Board of Directors, and mailing the correspondence to our Secretary at Alector, Inc., 131 Oyster Point Boulevard, Suite 600, South San Francisco, California 94080. Our Secretary, in consultation with appropriate members of our Board of Directors as necessary, will review all incoming communications and, if appropriate, such communications will be forwarded to the appropriate member or members of our Board of Directors, or if none is specified, to the Chairperson of our Board of Directors.

Corporate Governance Guidelines and Code of Conduct

Our Board of Directors has adopted Corporate Governance Guidelines that address items such as the qualifications and responsibilities of our directors and director candidates and corporate governance policies and standards applicable to us in general. In addition, our Board of Directors has adopted a Code of Conduct that applies to all of our employees, officers, and directors, including our Chief Executive Officer, President and Head of Research and Development, and other executive and senior financial officers. The full text of our Corporate Governance Guidelines and our Code of Conduct is posted on the Corporate Governance portion of our website at https://investors.alector.com. We will post amendments to our Code of Conduct or waivers of our Code of Conduct for directors and executive officers on the same website.

Director Compensation

Directors who are also our employees receive no additional compensation for their service as directors. Dr. Rosenthal was our only employee director during the fiscal year ended December 31, 2022. See the section titled “Executive Compensation” for additional information about Dr. Rosenthal’s compensation.

- 16 -

The following table presents the total compensation that each of our non-employee directors received during the fiscal year ended December 31, 2022. Other than as set forth in the table, we did not pay any compensation, make any equity awards or non-equity awards to, or pay any other compensation to any of our non-employee directors in the fiscal year ended December 31, 2022.

Outstanding Equity Awards at Fiscal Year End

The following table lists all outstanding equity awards held by non-employee directors as of December 31, 2022:

- 17 -

- 18 -

Outside Director Compensation Policy

Our Board of Directors adopted an Outside Director Compensation Policy that provides for certain compensation to our non-employee directors. Under our Outside Director Compensation Policy, each non-employee director received the following cash and equity compensation for their service as a member of our Board of Directors in 2022.

Outside Director Cash Compensation

Each non-employee director who serves as the chair of a committee receives only the annual fee as the chair of the committee and does not receive the additional annual fee as a member of the committee. All cash payments to non-employee directors are paid quarterly in arrears on a prorated basis.

2022 Outside Director Equity Compensation

For 2022, in addition to the cash compensation structure described above, our Outside Director Compensation Policy provides the following equity compensation program for non-employee directors. Each non-employee director who first joins us (other than a director who becomes a non-employee director as a result of terminating employment with us) automatically will be granted on the first trading date on or after his or her start date as a non-employee director a one-time, initial option award having a grant date fair value of approximately $550,000 (the “Initial Option”) Each Initial Option will vest as to 1/48th of the underlying shares on the one-month anniversary of the date the director’s service as a non-employee director commenced and as to 1/48th of the underlying shares each following month, subject to continued service through each relevant vesting date.

Further, on the date of each of our annual stockholder meetings, each non-employee director who, as of such annual meeting date, has served on the board as a director for at least the preceding six months, automatically will be granted an annual award having a grant date fair value of approximately $350,000. Such annual award will be split between a non-statutory stock option (“NSOs”) (the “Annual Option Award”) and restricted stock units (“RSUs”) (the “Annual RSU Award” and together with the Annual Option Award, the “Annual Award”). The number of NSOs will be determined by dividing the dollar value of the grant by the Black Scholes value of a share (with the shares covered by the award rounded down to the nearest whole share). The Black Scholes factor

- 19 -

will be averaged over the 30-days prior to the grant date of the Annual Award, as determined in accordance with the Company’s then-current accounting principles. The number of RSUs will be determined by a 2:1 NSO to RSU conversation ratio. As a result, the number of shares subject to the RSUs will be one half of the number of shares that would be subject to the NSOs granted on the same date. Accordingly, the value of the Annual Award will be split equally (50%-50%) between NSOs and RSUs.

Each Annual Option Award will vest as to 1/12th of the underlying shares each month after the Annual Award’s grant date and will vest in full on the earlier of the 12-month anniversary of the date of grant or on the date of our annual stockholder meeting following the date the Annual Award is granted, subject to continued service through each relevant vesting date. Each Annual RSU Award will vest in full on the earlier of the 12-month anniversary of the date of grant or on the date of our annual stockholder meeting following the date the Annual Award is granted, subject to continued service through each relevant vesting date. In the event of a change in control of our Company, all equity awards granted to a non-employee director (including those granted pursuant to our Outside Director Compensation Policy) will fully vest and become immediately exercisable, subject to continued service through the date of the change in control. Each Initial Option and the NSOs will have a term of 10 years and will have an exercise price per share equal to 100% of the fair market value of a share of our common stock on the date of grant. Each RSU will be valued at the fair market value of a share of our common stock on the date of grant.

In any fiscal year, a non-employee director may be paid, issued, or granted cash compensation and equity awards with a total value of no greater than $750,000 (increased to $1,000,000 in the fiscal year of his or her initial service as an outside director) with the value of an equity award based on its grant date fair value for purposes of this limit (annual director limit). Equity awards or cash compensation granted to a non-employee director for his or her service as an employee or consultant (other than a non-employee director) does not count toward the annual director limit.

Compensation for our non-employee directors is not limited to the equity awards and payments set forth in our Outside Director Compensation Policy. Our non-employee directors remain eligible to receive equity awards and cash or other compensation outside of the Outside Director Compensation Policy, as may be provided from time to time at the discretion of our Board of Directors.

Our Outside Director Compensation Policy also provides for the reimbursement of our non-employee directors for reasonable, customary, and documented travel expenses to attend meetings of our Board of Directors.

- 20 -

PROPOSAL NO. 1 ELECTION OF DIRECTORS

Our Board of Directors is currently comprised of nine members. In accordance with our amended and restated certificate of incorporation, our Board of Directors is divided into three staggered classes of directors. At the Annual Meeting, three Class II directors will be elected for a three-year term to succeed the same class whose term is then expiring.

Each director’s term continues until the election and qualification of his or her successor, or such director’s earlier death, resignation, or removal. Any increase or decrease in the number of directors will be distributed among the three classes so that, as nearly as possible, each class will consist of one-third of our directors. This classification of our Board of Directors may have the effect of delaying or preventing a change-in-control of Alector.

Nominees

Our Corporate Governance and Nominating Committee has recommended, and our Board of Directors has approved Elizabeth Garofalo, M.D., Terry McGuire, and Kristine Yaffe, M.D. as nominees for election as Class II directors at the Annual Meeting. If elected, Drs. Garofalo and Yaffe and Mr. McGuire will serve as Class II directors until our 2026 annual meeting of stockholders and until their successors are duly elected and qualified. Each of the nominees is currently a director of Alector. For information concerning the nominees, please see the section titled “Board of Directors and Corporate Governance.”

If you are a stockholder of record and you sign your proxy card or vote by telephone or over the Internet but do not give voting instructions with respect to the election of directors, your shares will be voted “FOR” the election of Drs. Garofalo and Yaffe and Mr. McGuire. We expect that each of Drs. Garofalo and Yaffe and Mr. McGuire will accept such nomination; however, in the event that a director nominee is unable or declines to serve as a director at the time of the Annual Meeting, the proxies will be voted for any nominee designated by our Board of Directors to fill such vacancy. If you are a street name stockholder and you do not give voting instructions to your broker or nominee, your broker will leave your shares unvoted on this matter.

Vote Required

The election of each director requires a plurality vote of the shares of our common stock present (including virtually) or represented by proxy at the Annual Meeting and entitled to vote thereon to be approved. Brokerage firms do not have authority to vote customers’ unvoted shares held by the firms in street name for the election of the director. As a result, any shares not voted by a customer will be treated as a broker non-vote. Such broker non-votes and abstentions will have no effect on the results of this proposal.

OUR BOARD OF DIRECTORS RECOMMENDS A VOTE “FOR”

THE ELECTION OF EACH OF THE DIRECTOR NOMINEES NAMED ABOVE.

- 21 -

PROPOSAL NO. 2

RATIFICATION OF APPOINTMENT OF

INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

Our Audit Committee has appointed Ernst & Young LLP (“Ernst & Young”), an independent registered public accounting firm, to audit our consolidated financial statements for the fiscal year ending December 31, 2023. During the fiscal year ended December 31, 2022 and since 2017, Ernst & Young has served as our independent registered public accounting firm.

Notwithstanding the appointment of Ernst & Young and even if our stockholders ratify the appointment, our Audit Committee, in its discretion, may appoint another independent registered public accounting firm at any time during the fiscal year if our Audit Committee believes that such a change would be in the best interests of the Company and our stockholders. At the Annual Meeting, our stockholders are being asked to ratify the appointment of Ernst & Young as our independent registered public accounting firm for the fiscal year ending December 31, 2023. Our Audit Committee is submitting the appointment of Ernst & Young to our stockholders because we value our stockholders’ views on our independent registered public accounting firm and as a matter of good corporate governance. A representative of Ernst & Young is expected to be present at the Annual Meeting, will have an opportunity to make a statement if he or she wishes to do so, and is expected to be available to respond to appropriate questions from our stockholders.

If our stockholders do not ratify the appointment of Ernst & Young, our Board of Directors may reconsider the appointment.

Fees Paid to the Independent Registered Public Accounting Firm

The following table presents fees for professional audit services and other services rendered to us by Ernst & Young for the fiscal years ended December 31, 2022 and 2021.

Auditor Independence

In the fiscal year ended December 31, 2022, there were no other professional services provided by Ernst & Young, other than those listed above, that would have required our Audit Committee to consider their compatibility with maintaining the independence of Ernst & Young.

- 22 -

Audit Committee Policy on Pre-Approval of Audit and Permissible Non-Audit Services of Independent Registered Public Accounting Firm

Our Audit Committee has established a policy governing our use of the services of our independent registered public accounting firm. Under this policy, our Audit Committee is required to pre-approve all audit and permissible non-audit services, other than de minimis non-audit services, performed by our independent registered public accounting firm in order to ensure that the provision of such services does not impair the public accountants’ independence. All fees paid to Ernst & Young for the fiscal years ended December 31, 2022 and 2021 were pre-approved by our Audit Committee.

Vote Required

The ratification of the appointment of Ernst & Young as our independent registered public accounting firm for our fiscal year ending December 31, 2023 requires the affirmative vote of a majority of the shares of our common stock present (including virtually) or represented by proxy at the Annual Meeting and entitled to vote thereon. Abstentions will have the effect of a vote “Against” the proposal. Brokerage firms have authority to vote customers’ unvoted shares held by the firms in street name on this proposal. If a broker does not exercise this authority, such broker non-votes will have no effect on the results of this proposal.

THE BOARD OF DIRECTORS RECOMMENDS A VOTE “FOR”

THE RATIFICATION OF THE APPOINTMENT OF ERNST & YOUNG.

- 23 -

PROPOSAL NO. 3

ADVISORY VOTE ON THE COMPENSATION

OF OUR NAMED EXECUTIVE OFFICERS

This stockholder advisory vote, commonly known as “say-on-pay,” is required pursuant to Section 14A of the Exchange Act and gives our stockholders the opportunity to approve or not approve, on a non-binding advisory basis, the compensation paid to our Chief Executive Officer and the other officers named in the Summary Compensation Table (“Named Executive Officers”) as disclosed in this proxy statement.

The Board recommends a vote “FOR” the following resolution:

“RESOLVED, that the stockholders of Alector, Inc. approve, on an advisory basis, the compensation of the Named Executive Officers, as disclosed in the proxy statement, including the Compensation Discussion and Analysis, the compensation tables, and any related narrative discussion.”

We became a publicly traded company in February 2019, and since that time we have made significant changes to our executive compensation program to reflect our transition from a private to public company. This is the third time we have included an advisory “say-on-pay” vote at the annual meeting of our stockholders. In 2022, our stockholders approved the “say-on-pay” vote with 98% of the votes cast (excluding broker non-votes and abstentions) in support of the compensation of our named executive officers as disclosed in our 2022 proxy statement. Each year, we intend to submit the executive compensation of our named executive officers to an advisory vote at our annual meeting of stockholders, consistent with the “say-when-on-pay” recommendation from our stockholders at our 2021 annual meeting, until such time as the say-when-on-pay proposal is brought before our stockholders again.

The Compensation Discussion and Analysis, beginning on page 28, describes our executive compensation programs and the compensation decisions made by our Compensation Committee and Board of Directors for the fiscal year ended December 31, 2022 with respect to the Named Executive Officers. As described in detail in the Compensation Discussion and Analysis and highlighted in the section captioned “Executive Summary,” our Compensation Committee believes that the most effective compensation program is designed to provide a substantial portion of executive compensation in the form of variable, at-risk pay which is earned based on performance. Our Compensation Committee thoughtfully employs the primary compensation elements of base salary, annual cash incentives, and long-term equity awards, to achieve these objectives.

Our Board of Directors is asking you to support this proposal. Because your vote is advisory, it will not be binding. However, the Compensation Committee and Board of Directors will review the voting results in their entirety and take them into consideration when making future decisions regarding named executive officer compensation.

Vote Required

The approval, on an advisory basis, of the compensation of our named executive officers requires the affirmative vote of a majority of the shares of our common stock present (including virtually) or represented by proxy at the Annual Meeting and entitled to vote thereon. Abstentions will have the effect of a vote “Against” the proposal. Brokerage firms do not have authority to vote customers’ unvoted shares held by the firms in street name on this proposal. As a result, any shares not voted by a customer will be treated as a broker non-vote. Such broker non-votes will have no effect on the results of this vote.

THE BOARD OF DIRECTORS RECOMMENDS A VOTE “FOR”

THE APPROVAL OF THE COMPENSATION OF OUR NAMED EXECUTIVE OFFICERS

AS DISCLOSED IN THIS PROXY STATEMENT.

- 24 -

AUDIT COMMITTEE REPORT

The information contained in the following Audit Committee Report shall not be deemed to be soliciting material or to be filed with the Securities and Exchange Commission, nor shall such information be incorporated by reference into any future filing under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended, except to the extent that Alector, Inc. (the “Company”) specifically incorporates it by reference in such filing.

The Audit Committee serves as the representative of our Board of Directors with respect to its oversight of:

The Audit Committee reviewed and discussed the audited financial statements for the fiscal year ended December 31, 2022 with management and Ernst & Young LLP, the Company’s independent registered public accounting firm. The Audit Committee has discussed with Ernst & Young LLP the matters required to be discussed by the applicable requirements of the Public Company Accounting Oversight Board (“PCAOB”) and the Securities and Exchange Commission (“SEC”).

The Audit Committee is composed of four non-employee directors. Our Board of Directors has determined that each member of the Audit Committee is independent and that Mr. Lavigne qualifies as an “audit committee financial expert” under the SEC rules.

The Audit Committee has received and reviewed the written disclosures and the letter from Ernst & Young LLP required by the applicable requirements of the PCAOB regarding Ernst & Young LLP’s communications with the Audit Committee concerning independence and has discussed with Ernst & Young LLP its independence. In addition, the Audit Committee has discussed with Ernst & Young LLP its independence from management and the Company, including matters in the letter from Ernst & Young LLP required by PCAOB Rule 3526, Communication with Audit Committees Concerning Independence, and considered the compatibility of any non-audit services with Ernst & Young LLP’s independence.

Based on the review and discussions referred to above, the Audit Committee recommended to our Board of Directors that the Company’s audited consolidated financial statements be included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2022 for filing with the SEC. The Audit Committee also has selected Ernst & Young LLP as the independent registered public accounting firm for fiscal year 2023. Our Board of Directors recommends that stockholders ratify this selection at the Annual Meeting.

Respectfully submitted by the members of the Audit Committee of the Board of Directors:

Louis J. Lavigne, Jr. (Chairperson)

Elizabeth Garofalo, M.D.

Terry McGuire

Kristine Yaffe, M.D.

- 25 -

EXECUTIVE OFFICERS

The following table identifies certain information about our executive officers as of March 31, 2023. Our executive officers are appointed by, and serve at the discretion of, our Board of Directors. There are no family relationships among any of our directors or executive officers.

Arnon Rosenthal, Ph.D. For a biography of Dr. Rosenthal, please see the section titled “Board of Directors and Corporate Governance.”

Sara Kenkare-Mitra, Ph.D., President and Head of Research and Development. Dr. Kenkare-Mitra has served as our President and Head of Research and Development since December 2021. Prior to joining Alector, Dr. Kenkare-Mitra held roles of increasing responsibility at Genentech over the course of 23 years. She most recently served as Senior Vice President, Development Sciences in Genentech’s research and early development unit. During her tenure at Genentech, Dr. Kenkare-Mitra led a large, integrated global organization of approximately 650 employees and played a key role in the filing of more than 100 investigational new drug/clinical trial applications around the world and the approval of 15 medicines for diverse diseases, including cancers and neurological diseases. Her team also enabled the successful development and approval of over 15 companion diagnostics. Dr. Kenkare-Mitra received her Ph.D. in Pharmaceutical Chemistry from the University of California, San Francisco (“UCSF”), where she also stayed on as a Post-Doctoral Fellow in the School of Medicine and completed a fellowship in Clinical Pharmacology before joining Genentech. She also holds adjunct faculty positions in the Department of Bioengineering and Therapeutic Sciences at UCSF and the University of the Pacific in Stockton. Dr. Kenkare-Mitra is an elected member of the National Academy of Medicine and elected fellow of the Association for the Advancement of Science. Dr. Kenkare-Mitra has been widely recognized for her work and leadership in the industry with awards such as the American Association of Pharmaceutical Scientists’ Alice E. Till Advancement of Women in Pharmaceutical Sciences Recognition, Endpoints’ 20 Most Extraordinary Women in Biopharma, Fierce Pharma’s Fiercest Women in the Life Sciences, and UCSF’s Distinguished Alumnus of the Year. She has served as a board member of the Genentech Foundation and the Association of Women in Science.

Marc Grasso, M.D., Chief Financial Officer. Dr. Grasso has served as our Chief Financial Officer since February 2022. Dr. Grasso joined Alector from Kura Oncology, Inc. (“Kura”), where he served as Chief Financial Officer and Chief Business Officer since August 2018. Prior to Kura, he served as Managing Director of Stifel Financial Corp., where he was responsible for building and managing the west coast life sciences and biotechnology investment banking business from March 2013 to July 2018. From June 2010 to February 2013, Dr. Grasso was Managing Director of Investment Banking in the Global Healthcare Group at UBS, focusing on the biotechnology sector. Prior to that, Dr. Grasso was Managing Director of Investment Banking at Leerink Swann LLC (now Leerink Partners LLC), where he was instrumental in the west coast expansion of its franchise. Prior to that, Dr. Grasso held key positions at Morgan Stanley, Credit Suisse First Boston, and Deutsche Bank Alex. Brown Inc. Dr. Grasso received his M.D. from The Johns Hopkins University School of Medicine. He obtained an A.B. in molecular biology with honors from Princeton University.

Gary Romano, M.D., Ph.D., Chief Medical Officer. Dr. Romano brings more than 25 years of experience in neurodegenerative disease, including 18 years in industry roles at Merck, the Janssen Pharmaceutical Companies of Johnson & Johnson, and Passage Bio. Dr. Romano served as the Chief Medical Officer of Passage Bio until May 2021, where he was responsible for the clinical development of gene therapies targeting rare monogenic central nervous system disorders and achieved Investigational New Drug and Clinical Trial Application

- 26 -

clearances for three gene therapies. Prior to Passage Bio, Dr. Romano oversaw clinical development of the neurodegenerative disease portfolio for more than five years at Janssen as the Deputy Leader, Neurodegenerative Disease Area and Head of Development, Neurodegenerative Disease. He previously held other leadership positions at Janssen, including Head of Neuroscience Biomarkers and Head of Early Clinical Development. Earlier in his career, Dr. Romano served as the Alzheimer’s Disease Therapeutic Area Group Co-Leader and Leader, Neuroscience Experimental Medicine at Merck. He has served on the executive committee of the Innovative Medicines Initiative – European Prevention of Alzheimer’s Dementia, and as the industry co-chair of the Critical Path Institute Coalition Against Alzheimer’s Disease. Dr. Romano currently serves on the board of directors of the ALS Hope Foundation and is an adjunct member of the neurology department at the Lewis Katz School of Medicine at Temple University. Dr. Romano earned a B.S. in Biology from Trinity College, a Ph.D. in Molecular Neurobiology from Rockefeller University, and an M.D. from The Johns Hopkins University School of Medicine. He completed his medical internship, neurology residency, and neuromuscular fellowship at the University of Pennsylvania.

- 27 -

EXECUTIVE COMPENSATION

Compensation Discussion and Analysis

This Compensation Discussion and Analysis describes the principles underlying the material components of our compensation program for our executive officers, including the named executive officers in the “Summary Compensation Table.” We also provide an overview of the overall objectives of the program and the factors relevant to an analysis of these policies and decisions, and how we use our executive compensation program to drive our performance.

Named Executive Officers

Our named executive officers for the year ended December 31, 2022 are:

Executive Summary

Company Background and 2022 Business Highlights

Our mission is to develop therapies that empower the immune system to cure neurodegeneration and other diseases. We are a clinical-stage biopharmaceutical company pioneering immuno-neurology, a novel therapeutic approach for the treatment of neurodegeneration. Immuno-neurology targets immune dysfunction as a root cause of multiple pathologies that are drivers of degenerative brain disorders. We are developing therapies designed to counteract these pathologies simultaneously by restoring healthy immune function to the brain.

Our executive compensation program seeks to incentivize and reward strong corporate performance. Highlights of our 2022 corporate performance and executive compensation program are set forth below.

- 28 -

In addition, we continued with multiple early-stage programs and made significant progress on other internal corporate goals.

Key 2022 Compensation Decisions

Aligned with our results and performance in 2022 as outlined above, we took several actions related to our compensation program.

Compensation Philosophy

The goals of our executive compensation program are to attract, engage, and retain executive offers who share our vision and are deeply connected to our mission. Our overall compensation philosophy is market-based and enables our executive officers to share in the Company’s long-term success. We strive to incentivize these executive officers to achieve our short-term and long-term business objectives in order to increase long-term value and increase stockholder value. Our program combines competitive cash and equity award opportunities in the forms and proportions that we believe will motivate our executive officers to increase stockholder value over the long term. We routinely review our policies and program design.

Our executive compensation program delivers excellent rewards in line with individual and company performance using the following specific compensation methods:

- 29 -

Overview of Executive Compensation Program

Our executive compensation program is designed to be competitive and to appropriately balance our goals of attracting, engaging, and retaining our executive officers and driving company performance. To align our executive officers’ interests with those of our stockholders and to motivate and reward individual initiative and effort, a substantial portion of each executive officer’s total target annual direct compensation opportunity is “at-risk,” meaning the amounts paid to each executive officer will vary based on our Company performance and such executive officer’s contributions to that performance.

Consistent with our philosophy of aligning executive pay with the short- and long-term performance of the Company, and to align the interests of management and stockholders, the Company’s compensation programs are designed to provide the majority of executive compensation in the form of variable, at-risk pay. Our Compensation Committee thoughtfully employs the primary compensation elements of base salary, short-term annual cash incentives, and long-term equity awards, to achieve these objectives.

In 2022, target pay packages were as follows:

The percentages above were calculated using base salary, target annual cash incentive compensation, and the grant date fair value of our long-term incentive vehicles. Similar to our industry-based peers, we have gradually shifted the equity mix for our executives and employees towards the use of RSUs, which incentivizes executives to create value for the Company and shareholders, while also managing the equity pool with discipline, due to the fact that RSUs are linked to stock price performance and are an efficient way to deliver equity.

Executive Compensation Governance

We are committed to a strong performance orientation in our compensation program and effective corporate governance practices for a company at our development stage and industry. With guidance from an independent compensation consultant, we maintain sound compensation and governance standards, and we adopt best practices in establishing and administering policies in support of these standards.

The Compensation Committee evaluates our executive compensation program regularly to ensure that it supports our short-term and long-term goals to compete for executive talent, as well as protect our stockholders’ interests. Specifically, we undertake two compensation cycles per year, with cash compensation decisions (bonus payout and merit increase) the focus of the first quarter compensation cycle, and equity decisions the focus of the third quarter compensation cycle. This structure enables a tighter pay-for-performance link and two opportunities for a rewards conversation each year.

- 30 -

Our pay-for-performance philosophy and compensation governance practices provide an appropriate framework to our executives to achieve our strategic goals without encouraging them to take excessive risks in their business decisions. Some of our practices include:

Stockholder Engagement

The Company is committed to engagement with stockholders. We review any feedback we receive from our stockholders about our executive compensation program, including through the say-on-pay vote, discussed below, to ensure that we understand key matters of interest to them, and to enable us to take that feedback into consideration for our compensation decisions.

“Say-on-Pay” Voting

At our 2022 annual meeting, we held a non-binding advisory vote on executive compensation (commonly referred to as a “say-on-pay” vote). This say-on-pay received overwhelming support from our stockholders, with over 98% of votes cast in support of the proposal (excluding broker non-votes and abstentions). The Compensation Committee believes this vote demonstrated our stockholders’ positive view of our pay-for-performance philosophy and the appropriateness of our executive compensation structure.

Compensation Determination Process

Role of Compensation Committee and Board of Directors

Our Compensation Committee is responsible for overseeing the total compensation of our executive officers. In this capacity, our Compensation Committee designs, implements, reviews, and approves all compensation for our Chief Executive Officer and our other executive officers. The Compensation Committee formally met five times during fiscal year 2022 to review and discuss matters related to compensation of our employees and executive officers. Some of these meetings were held with members of management in attendance and some were held in closed session. Most of the meetings also included representatives from our compensation consulting firm (as

- 31 -

described below). Typically, the Compensation Committee reports to the Board of Directors on its discussions and on occasion seeks input from the Board of Directors regarding the decisions to be made and other actions to be taken with regard to our executive officers’ compensation. Our Compensation Committee’s recommendations regarding executive compensation are based on the Compensation Committee’s assessment of the performance of the Company and each individual executive officer, as well as other factors, such as prevailing industry trends and the competitive market for executive talent. The Compensation Committee makes the final decisions regarding executive compensation.

Role of Management

In 2022, our Chief Executive Officer and Chief People Officer made recommendations to our Compensation Committee, attended certain Compensation Committee meetings, and were involved in the process for determining our executive officers’ compensation, provided that neither our Chief Executive Officer nor our Chief People Officer made recommendations as to their own compensation or participated in Compensation Committee discussion of their own compensation. Our Compensation Committee considers management’s recommendations but is not required to follow any recommendations and may adjust compensation up or down as it determines in its discretion. Our Compensation Committee reviews the recommendations and other data and makes decisions as to each executive officer’s total compensation, as well as each individual pay component. At certain meetings in 2022, the Compensation Committee met in executive sessions and our Chief Executive Officer and Chief People Officer were not present when it deliberated and voted on the compensation of the executive officers.

Role of Independent Compensation Consultant

Our Compensation Committee is authorized to retain the services of one or more executive compensation advisors, as it sees fit, in connection with the establishment of our compensation programs and related policies. Previously, our Compensation Committee retained Aon’s Human Capital Solutions practice, a division of Aon plc (“Aon”), as independent compensation consultant. In August 2022, our Compensation Committee elected to replace Aon and to retain Pearl Meyer & Partners, LLC (“Pearl Meyer”) as its independent compensation consultant to provide it with information, recommendations, and other advice relating to executive compensation on an ongoing basis. Accordingly, Pearl Meyer currently serves at the discretion of our Compensation Committee. Our Compensation Committee engaged Pearl Meyer to assist in developing an appropriate group of peer companies, help us determine the appropriate level of overall compensation for our executive officers, and assess each separate element of compensation, with a goal of ensuring that the compensation we offer to our executive officers is competitive and fair.

Use of Peer Group

The Compensation Committee approves a peer group of companies as a reference group to provide a broad perspective on competitive pay levels and practices. The peers are reviewed on an annual basis in light of the fast-moving changes at the Company and in our industry. In 2022, we undertook this review with the assistance and recommendations of Pearl Meyer, who provided competitive market analysis of the base salary, annual cash incentive awards, and long-term incentive compensation of our executive officers compared against our compensation peer group and reviewed other market practices and trends.

2021 Peer Group

In August 2021, the Compensation Committee approved a peer group for use in making third quarter 2021 equity award decisions, first quarter 2022 base salary and annual target bonus decisions, and for use in assessing compensation data for senior executive new hire packages. The Compensation Committee used the following criteria in determining the appropriate peers:

- 32 -

Based on these criteria and considerations, our peer group for 2021, as approved by our Compensation Committee, consisted of the following 22 companies:

2022 Peer Group

In August 2022, the Compensation Committee approved a peer group for use in making third quarter 2022 equity award decisions and first quarter 2023 base salary and annual target bonus decisions. The Compensation Committee used the following criteria in determining the appropriate peers:

Based on these criteria and considerations, eight companies were added to form the 2022 peer group, and eight were removed. Our peer group for 2022, as approved by our Compensation Committee, consisted of the following 21 companies:

- 33 -

In setting compensation for our executive officers, including our named executive officers, the Compensation Committee uses competitive compensation data from an annual total compensation study of selected peer companies and relevant survey sources to inform its decisions about overall compensation opportunities and specific compensation elements. However, the Compensation Committee uses our compensation peer group as one data point when setting executive pay packages. The overall compensation philosophy focuses at or near a target percentile, particularly in respect to target cash compensation and equity grants. In addition, our compensation decisions are based on the consideration of many factors, including, but not limited to, individual and company performance, market data, internal equity, value of unvested equity, experience, and strategic needs. As a result of evaluating compensation based on the criteria described above, total target compensation for our named executive officers may in certain circumstances be above or below the target levels of the peer group.

Pay Components

The Company’s executive compensation program consists of three primary elements: base salaries, annual cash incentives, and long-term equity awards:

- 34 -

Base Salary

Base salary is the only fixed component of our executive officers’ total cash compensation and provides competitive pay to attract and retain our executives. Annual salary decisions are made in recognition of competitive data as well as the skills and experience that each individual brings to the Company and the performance and contributions each makes.

Base salary changes in 2022 varied by executive due either to merit increases or to market adjustments. Other factors were considered such as tenure, experience, and the role of the individual.

The 2022 base salaries for our named executive officers were as follows and were effective as of March 1, 2022, except as noted below:

The 2023 base salaries, effective as of March 1, 2023, and 2023 annual bonus targets for our current executive officers are as follows:

Executive Incentive Compensation Plan

The Executive Incentive Compensation Plan (the “Bonus Plan”) is designed to provide a financial incentive to reward executives for the achievement of a series of program-specific, pipeline, and functional corporate goals. Payments under the plan are ultimately based on achievement of these pre-established corporate goals. Actual performance against targets, as measured by these pre-established corporate goals, funds the incentive payouts. The corporate bonus pool can be funded between 0% to a maximum of 150% of target funding levels. The total

- 35 -

bonus payout cannot exceed the total amount of funding in the pool. Annual target bonuses are set based on factors such as the executive’s past contributions, tenure, experience, and role and the annual target bonuses provided by companies in our compensation peer group to their similarly situated executives. Our Chief Executive Officer receives a bonus based entirely on corporate performance since he has ultimate operational responsibility for corporate performance. Our other named executive officers’ target bonus weighting (except for Ms. Rubinstein who did not participate in the Bonus Plan) is primarily linked to corporate performance (80%), with a smaller weight applied to the individual performance component (20%), given their broad influence over corporate performance. The individual performance component of the bonus for these executive officers can be modified up to 150% or down to 0% dependent on performance in the prior year. In addition, the Compensation Committee retains flexibility to increase or decrease any and all compensation components to reflect performance. Bonuses are typically paid in the quarter following the end of the performance period.

The annual bonus target percentage for our Chief Executive Officer increased from 55% in 2021 to 60% in 2022, to better align with market norms. The annual bonus target percentages for our other named executive officers remained flat in 2022, which was deemed appropriate according to peer and market data. The bonuses paid to each of our named executive officers in 2022 under our Bonus Plan are also set forth in the “Non-Equity Incentive Plan Compensation” column of the Summary Compensation Table below.

Bonuses for all employees, including our participating named executive officers, for the fiscal year ended December 31, 2022 were allocated from a bonus pool funded based on performance against a number of high-impact project goals and cross-functional goals. The project goals related to specific programs, trials, and corporate progress. The cross-functional goals included goals related to research and development, positioning for future growth and development, and other functional goals. The combination of the project and cross-functional goals was intended to drive both specific technical achievement and continue to build the foundation for future company growth and advancements.

In December 2021, the Compensation Committee reviewed and the Board of Directors approved the corporate goals and objectives for 2022, as summarized in the table below. At the time the 2022 corporate goals were set, the Board of Directors and management believed that such goals were challenging, and that achieving them would require not only continued strong progress on research and clinical development, manufacturing and operational capabilities, and prudent fiscal and legal management, but also a high level of effort and execution on the part of our executive officers. These goals were viewed as critical drivers of our long-term success and ability to generate sustained growth in shareholder value. Our corporate goals were intended to drive these key objectives by establishing specific, measurable criteria that could be used to evaluate the performance of our executive team and the Company in general. We believed that achievement of these goals would have a direct impact on creating value for our stockholders.

- 36 -

The Compensation Committee also applied a performance weighting to each goal relative to our overall performance to reflect the prioritization of key business objectives, as summarized below. Each goal was measured individually and then such individual amounts were aggregated to determine the 2022 corporate bonus payout, subject to the Compensation Committee’s discretion to alter bonus funding and payouts. The 2022 corporate performance bonuses were earned based upon achievement of such performance and stretch goals, as follows:

Additionally, the Compensation Committee and the Board of Directors approved several stretch goals as follows:

- 37 -

To determine our corporate performance percentage for 2022, our Compensation Committee employed a holistic analysis that took into account both the extent to which the performance goals had been achieved or exceeded as well as the relative difficulty of achieving the goals that were met and those that were only partially met. In January 2023, the Compensation Committee reviewed the progress against the applicable 2022 goals. We accomplished and over-attained several target goals, largely achieved two stretch goals, and made significant progress on the remaining goals:

Based on the Company’s achievement of these goals, the Compensation Committee funded the Company’s corporate bonus pool at 103% of target levels.

- 38 -

The resulting bonuses to our named executive officers were as follows:

Long-Term Equity Incentive Compensation

We believe long-term equity incentive compensation is an effective means for focusing our executive officers, including the named executive officers, on driving strong performance and increased stockholder value over a multi-year period, provides a meaningful reward for long-term value creation, and motivates them to remain employed with us. This approach aligns the contributions of our executive officers with the long-term interests of our stockholders and allows them to participate in any future appreciation in our common stock.

In 2022, we had four equity compensation plans: the 2017 Stock Option and Grant Plan (the “2017 Plan”), 2019 Equity Incentive Plan (the “2019 Plan”), 2019 Employee Stock Purchase Plan (the “2019 ESPP”), and 2022 Inducement Equity Incentive Plan (the “Inducement Plan”). The 2017 Plan was terminated; however, shares subject to awards granted under it will continue to be governed by the 2017 Plan. The Inducement Plan, effective January 1, 2022, provides for the granting of equity-based awards, including non-statutory stock options, restricted stock units, restricted stock, stock appreciation rights, performance shares, and performance stock units. The Inducement Plan was recommended for approval by the Compensation Committee and subsequently approved and adopted by the Board of Directors without stockholder approval pursuant to the applicable Nasdaq Listing Rules.

We determine long-term equity incentive compensation for our executive officers as part of our biannual compensation review (with cash compensation reviewed in the first quarter and equity compensation reviewed in the third quarter) taking into account competitive market analysis, the recommendations of our Chief Executive Officer with respect to such equity compensation (except regarding his own equity incentive compensation), the outstanding equity holdings of each executive officer, the projected impact of the proposed awards on our earnings, and our Company performance in 2022.

- 39 -

New Hire Equity Grants

On January 3, 2022, the Compensation Committee approved the grant of the following awards to Dr. Kenkare-Mitra as a form of inducement to join and remain with the Company: (i) an option to purchase 300,000 shares of our common stock, (ii) an award of 59,000 restricted stock units, and (iii) an award of 59,000 performance stock units. The option has an exercise price equal to $20.78 per share, which was the closing price of our common stock on the date of grant. One-fourth of the shares subject to the option vested on December 15, 2022, and the remaining shares vest monthly over the next 36 months in equal monthly amounts, subject to Dr. Kenkare-Mitra’s continued service through each such date. One-third of the shares subject to the restricted stock unit award vested on March 1, 2023, and one-twelfth of the remaining shares vest each quarter thereafter, subject to Dr. Kenkare-Mitra’s continued service through each such date. The vesting details for Dr. Kenkare-Mitra’s performance stock unit award are described below. Under Dr. Kenkare-Mitra’s change in control and severance agreement, the vesting of these awards may be accelerated upon a qualifying termination of her employment during the period beginning on the date of a change in control and ending 12 months following that change in control, as described below in the section captioned “Potential Payments on Termination or Change in Control.”

On March 1, 2022, the Compensation Committee approved the grant of an option to purchase 450,000 shares of our common stock to Dr. Grasso as a form of inducement to join and remain with the Company. The option has an exercise price equal to $15.49 per share, which was the closing price of our common stock on the date of grant. One forty-eighth of the shares subject to the option vested on March 7, 2022, and the remaining shares vest monthly in equal amounts, subject to Dr. Grasso’s continued service through each such date. Under Dr. Grasso’s change in control and severance agreement, the vesting of these awards may be accelerated upon a qualifying termination of his employment during the period beginning on the date of a change in control and ending 12 months following that change in control, as described below in the section captioned “Potential Payments on Termination or Change in Control.”

On May 27, 2022, the Compensation Committee approved the grant of the following awards to Dr. Romano as a form of inducement to join and remain with the Company: (i) an option to purchase 369,000 shares of our common stock and (ii) an award of 92,250 restricted stock units. The option has an exercise price equal to $9.20 per share, which was the closing price of our common stock on the date of grant. One forty-eighth of the shares subject to the option vested on June 23, 2022, and the remaining shares vest monthly in equal monthly amounts, subject to Dr. Romano’s continued service through each such date. Under Dr. Romano’s change in control and severance agreement, the vesting of these awards may be accelerated upon a qualifying termination of his employment during the period beginning on the date of a change in control and ending 12 months following that change in control, as described below in the section captioned “Potential Payments on Termination or Change in Control.”

Performance Stock Units

In 2021, our Compensation Committee determined that the addition of performance stock units would provide appropriate incentives for the Company’s executive officers. Performance goals were based on the achievement of certain stock price hurdles, described below. The performance stock units are denominated and settle in shares of the Company’s common stock.

Due to the proximity of hiring Dr. Kenkare-Mitra to the date at which the Performance Stock Unit program was created, six months prior, our Compensation Committee decided to include Dr. Kenkare-Mitra into the program. In January 2022, as a form of inducement to join and remain with the Company, we granted Dr. Kenkare-Mitra an award of performance stock units that are earned if the average closing price of our common stock for a period of 40 consecutive trading days (the “average closing stock price”) equals or exceeds certain stock price targets during the measurement period commencing on January 3, 2022 and ending on January 2, 2026, as follows:

- 40 -

If the stock price target is achieved, the performance stock units shall vest in four equal quarterly installments beginning with the first Company quarterly vesting date that is at least three months after the date the applicable stock price target is achieved. In addition, under Dr. Kenkare-Mitra’s change in control and severance agreement, the vesting of any performance stock units that become eligible to vest may be accelerated upon a qualifying termination of her employment during the period beginning on the date of a change in control and ending 12 months following that change in control, as described below in the section captioned “Potential Payments on Termination or Change in Control.”

The Performance Stock Unit program was suspended in 2022 for new grants due to significant stock price volatility and evolving growth trajectory of the business. Our Compensation Committee will consider the inclusion of performance stock units for future grant cycles based on circumstances at such future time.

Annual Equity Grants

In 2022, the long-term equity incentive compensation awarded to our executive officers based on our annual equity compensation review was granted in the form of stock options vesting over a four-year time-based schedule and restricted stock units vesting over a three-year time-based schedule. The equity mix comprised 75% restricted stock units and 25% stock options. This approach to long-term equity incentive compensation is consistent with market practice among our peer group and reinforces a strong pay-for-performance culture as the value of each award increases only if the value of our common stock appreciates from the grant date. Each award was granted on the following material terms:

Severance and Change in Control Protections

In November 2018, we adopted a Change in Control and Severance Agreement (the “Severance Agreement”) in which our named executive officers participate. The Severance Agreement provides participants with severance in the event of certain qualifying terminations, including following a change in control of our Company, and certain change in control benefits. We believe that these protections are necessary to provide our valuable executives with incentives to forego other employment opportunities and remain employed with us and to maintain continued focus and dedication to their responsibilities to maximize stockholder value, including if there is a potential transaction that could involve a change in control. In addition, these protections are available only if a named executive officer executes and does not revoke a general release of claims in favor of us. The

- 41 -

terms and levels of benefits provided to our named executive officers under the Severance Agreement were determined by our Compensation Committee, with input from our management team, and approved by our Board of Directors following a review of analysis prepared by our compensation consultant of relevant market data for other companies with whom we compete for executive talent.

For a summary of the material terms of the benefits provided to our named executive officers under the Severance Agreement and an estimate of the payments and benefits that may be received by our named executive officers under the Severance Agreements, see the section titled “Potential Payments on Termination or Change in Control” below.

Other Compensation

Retirement, Welfare, and Health Benefits

We maintain a tax-qualified retirement plan that provides eligible employees with an opportunity to save for retirement on a tax advantaged basis. All participants’ interests in their deferrals are 100% vested when contributed. Pre-tax contributions are allocated to each participant’s individual account and are then invested in selected investment alternatives according to the participants’ directions. The 401(k) plan is intended to qualify under Sections 401(a) and 501(a) of the Internal Revenue Code (the “Code”). As a tax-qualified retirement plan, contributions to the 401(k) plan and earnings on those contributions are not taxable to the employees until distributed from the 401(k) plan. Subject to limits under the Code, we match an amount equal to 50% of the first 6% of the eligible employee’s contributions with a maximum annual employer contribution of $5,000 per employee. Our executive officers are eligible to participate in our 401(k) plan.

Our health and welfare benefits include medical, dental, and vision benefits, long-term disability insurance, basic life insurance coverage, health savings accounts, and accidental death and dismemberment insurance. Our named executive officers also are eligible to participate in our Employee Stock Purchase Plan on the same terms as our other eligible employees. We design our employee benefits programs to be affordable and competitive in relation to the market, and compliant with applicable laws and practices. We adjust our employee benefits programs as needed based upon changes in applicable laws and market practices.

Perquisites and Other Personal Benefits

We do not provide perquisites or other personal benefits to our executive officers, including the named executive officers except in situations where we believe it is appropriate to assist an individual in the performance of his or her duties, to make our executive officers more efficient and effective, and for recruitment and retention purposes.

In the future, we may provide perquisites or other personal benefits in limited circumstances. All future practices with respect to perquisites or other personal benefits for executive officers will be approved and subject to periodic review by the Compensation Committee.

Employment and Consulting Agreements

We have entered into employment letters with each of our named executive officers, except for Linda Rubinstein. Each of these agreements was approved by our Board of Directors or our Compensation Committee. In connection with retaining Ms. Rubinstein as our interim Chief Financial Officer, we entered into a Confidential Consulting Agreement with FLG Partners, LLC (“FLG Partners”), of which Ms. Rubinstein is a partner, effective September 3, 2021 (the “Consulting Agreement”), pursuant to which FLG Partners served as an independent contractor to the Company. We agreed to pay FLG Partners at a rate of $600 per hour for Ms. Rubinstein’s services. As of February 25, 2022, Ms. Rubinstein no longer performed consulting services for Alector.

- 42 -

In filling each of our executive positions, our Board of Directors and the Compensation Committee recognized the need to develop competitive compensation packages to attract qualified candidates in a dynamic labor market. Our Board of Directors and our Compensation Committee were sensitive to the need to integrate new executive officers into the executive compensation structure that we were seeking to develop, balancing both competitive and internal equity considerations.

For information on the specific terms and conditions of the employment letters of the named executive officers, see the discussion of “Executive Employment Arrangements” below.

Additional Policies and Practices

Hedging and Pledging Prohibitions

As part of our Insider Trading Policy, our employees (including our executive officers and the non-employee members of our Board of Directors) are prohibited from trading in publicly-traded options, such as puts and calls, and other derivative securities with respect to our securities. This includes any hedging or similar transaction designed to decrease the risks associated with holding shares of our common stock.

In addition, our employees (including our executive officers and the non-employee members of our Board of Directors) are prohibited from holding our common stock in a margin account or pledging our securities as collateral for a loan.

Tax and Accounting Considerations

Deductibility of Executive Compensation

Generally, Section 162(m) of the Code (“Section 162(m)”) disallows a U.S. federal income tax deduction for public corporations of remuneration in excess of $1 million paid in any fiscal year to certain specified executive officers. The Company generally expects that all remuneration in excess of $1 million paid to a specified executive will not be deductible by us as a corporate entity unless it qualifies for the transition relief applicable to certain newly public companies. To maintain flexibility to compensate our executive officers in a manner designed to promote our short-term and long-term corporate goals, the Compensation Committee has not adopted a policy that all compensation must be deductible. The Compensation Committee believes that our shareholders’ interests are best served if its discretion and flexibility in awarding compensation is not restricted in order to allow such compensation to be consistent with the goals of our executive compensation program, even though some compensation awards may result in non-deductible compensation expense.

Accounting for Stock-Based Compensation

We follow the Financial Accounting Standard Board’s Accounting Standards Codification Topic 718 (“FASB ASC Topic 718”) for our stock-based compensation awards. FASB ASC Topic 718 requires us to measure the compensation expense for all share-based payment awards made to our employees and members of our Board of Directors, including options to purchase shares of our common stock and other stock awards, based on the grant date “fair value” of these awards. This calculation is performed for accounting purposes and reported in the executive compensation tables required by the federal securities laws, even though the recipient of the awards may realize no value from their awards.

Taxation of Parachute Payments and Deferred Compensation

We do not provide, and have no obligation to provide, any of our named executive officers with a “gross-up” or other reimbursement payment for any tax liability he or she might owe because of the application of Sections 280G, 4999, or 409A of the Code. If any of the payments or benefits provided for under the Severance Agreement or otherwise payable to a named executive officer would constitute “parachute payments” within the

- 43 -

meaning of Section 280G of the Code and could be subject to the related excise tax, he or she would receive either full payment of such payments and benefits or such lesser amount that would cause no portion of the payments and benefits being subject to the excise tax, whichever results in the greater after-tax benefits to our named executive officer.

Compensation Committee Interlocks and Insider Participation

In 2022, our Compensation Committee consisted of David Wehner, Louis J. Lavigne, Jr., Paula Hammond, Ph.D., and effective May 1, 2022, Elizabeth Garofalo, M.D. None of the members of our Compensation Committee is or has ever been an officer or employee of Alector. None of our executive officers currently serves, or in the past year has served, as a member of the board or compensation committee (or other board committee performing equivalent functions or, in the absence of any such committee, the entire board) of any entity that has one or more executive officers serving on our Board of Directors or Compensation Committee.

Compensation Committee Report

The Compensation Committee has reviewed and discussed with management the Compensation and Discussion Analysis provided above. Based on its review and discussions, the Compensation Committee recommended to the Board of Directors that the Compensation and Discussion Analysis be included in this proxy statement and our Annual Report on Form 10-K for our fiscal year ended December 31, 2022.

Compensation Committee

David Wehner (Chairperson)

Elizabeth Garofalo, M.D.

Louis J. Lavigne, Jr.

Paula Hammond, Ph.D.

The information contained in this report shall not be deemed to be “soliciting material” or “filed” with the SEC or subject to the liabilities of Section 18 of the Exchange Act, except to the extent that the Company specifically requests that the information be treated as soliciting material or incorporates it by reference into a document filed under the Securities Act of 1933, as amended (“Securities Act”), or the Exchange Act.

- 44 -

Summary Compensation Table for Fiscal Years 2022, 2021, and 2020

The following table provides information regarding the compensation awarded to, or earned by, our named executive officers during 2022, 2021, and 2020.

- 45 -

Grants of Plan-Based Awards

The following table provides information regarding grants of plan-based awards to each of our named executive officers during the fiscal year ended December 31, 2022.

- 46 -

- 47 -

Outstanding Equity Awards at Fiscal Year-End

The following table presents certain information concerning equity awards held by our named executive officers, as of December 31, 2022.