Sec Form 4 Filing - GORDON CARL L @ Alector, Inc. - 2019-02-11

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person GORDON CARL L 2. Issuer Name and Ticker or Trading Symbol Alector, Inc. [ ALEC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O ORBIMED ADVISORS, LLC, 601 LEXINGTON AVENUE, 54TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 02/11/2019 (Street) NEW YORK, NY10022 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 02/11/2019 C 405,925 A 405,925 I See footnotes ( 2 ) ( 3 ) Common Stock 02/11/2019 C 4,282,288 A 4,688,213 I See footnotes ( 2 ) ( 3 ) Common Stock 02/11/2019 C 2,029,626 A 6,717,839 I See footnotes ( 2 ) ( 3 ) Common Stock 02/11/2019 C 2,280,479 A 8,998,318 I See footnotes ( 2 ) ( 3 ) Common Stock 02/11/2019 C 1,012,282 A 10,010,600 I See footnotes ( 2 ) ( 3 ) Common Stock 02/11/2019 C 266,437 A 10,277,037 I See footnotes ( 2 ) ( 3 ) Common Stock 02/11/2019 P 157,939 A $ 19 10,43 4,976 I See footnotes ( 2 ) ( 3 ) Common Stock 02/11/2019 C 94,075 A 94,075 I See footnotes ( 3 ) ( 4 ) Common Stock 02/11/2019 C 992,437 A 1,086,512 I See footnotes ( 3 ) ( 4 ) Common Stock 02/11/2019 C 470,374 A 1,556,886 I See footnotes ( 3 ) ( 4 ) Common Stock 02/11/2019 C 528,510 A 2,085,396 I See footnotes ( 3 ) ( 4 ) Common Stock 02/11/2019 C 234,601 A 2,319,997 I See footnotes ( 3 ) ( 4 ) Common Stock 02/11/2019 C 85,295 A 2,405,292 I See footnotes ( 3 ) ( 4 ) Common Stock 02/11/2019 P 50,561 A $ 19 2,455,853 I See footnotes ( 3 ) ( 4 ) Common Stock 02/11/2019 P 203,200 A $ 19 203,200 I See footnotes ( 3 ) ( 5 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Series A-1 Preferred Stock ( 1 ) 02/11/2019 C 405,925 ( 1 ) ( 1 ) Common Stock 405,925 $ 0 0 I See footnotes ( 2 ) ( 3 ) Series A-1 Preferred Stock ( 1 ) 02/11/2019 C 94,075 ( 1 ) ( 1 ) Common Stock 94,075 $ 0 0 I See footnotes ( 3 ) ( 4 ) Series A-2 Preferred Stock ( 1 ) 02/11/2019 C 4,282,288 ( 1 ) ( 1 ) Common Stock 4,282,288 $ 0 0 I See footnotes ( 2 ) ( 3 ) Series A-2 Preferred Stock ( 1 ) 02/11/2019 C 992,437 ( 1 ) ( 1 ) Common Stock 992,437 $ 0 0 I See footnotes ( 3 ) ( 4 ) Series B Preferred Stock ( 1 ) 02/11/2019 C 2,029,626 ( 1 ) ( 1 ) Common Stock 2,029,626 $ 0 0 I See footnotes ( 2 ) ( 3 ) Series B Preferred Stock ( 1 ) 02/11/2019 C 470,374 ( 1 ) ( 1 ) Common Stock 470,374 $ 0 0 I See footnotes ( 3 ) ( 4 ) Series C Preferred Stock ( 1 ) 02/11/2019 C 2,280,479 ( 1 ) ( 1 ) Common Stock 2,280,479 $ 0 0 I See footnotes ( 2 ) ( 3 ) Series C Preferred Stock ( 1 ) 02/11/2019 C 528,510 ( 1 ) ( 1 ) Common Stock 528,510 $ 0 0 I See footnotes ( 3 ) ( 4 ) Series D Preferred Stock ( 1 ) 02/11/2019 C 1,012,282 ( 1 ) ( 1 ) Common Stock 1,012,282 $ 0 0 I See footnotes ( 2 ) ( 3 ) Series D Preferred Stock ( 1 ) 02/11/2019 C 234,601 ( 1 ) ( 1 ) Common Stock 234,601 $ 0 0 I See footnotes ( 3 ) ( 4 ) Series E Preferred Stock ( 1 ) 02/11/2019 C 266,437 ( 1 ) ( 1 ) Common Stock 266,437 $ 0 0 I See footnotes ( 2 ) ( 3 ) Series E Preferred Stock ( 1 ) 02/11/2019 C 85,295 ( 1 ) ( 1 ) Common Stock 85,295 $ 0 0 I See footnotes ( 3 ) ( 4 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other GORDON CARL L C/O ORBIMED ADVISORS, LLC 601 LEXINGTON AVENUE, 54TH FLOOR NEW YORK, NY10022 X X Signatures /s/ Stephanie Yonker, attorney-in-fact 02/11/2019 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each of the Series A-1 Preferred Stock, Series A-2 Preferred Stock, Series B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock and Series E Preferred Stock automatically converted into shares of Common Stock on a one to one basis immediately prior to the completion of the Issuer's initial public offering of Common Stock and has no expiration date. ( 2 )The Shares are held of record by OrbiMed Private Investments IV-AL, LP ("OrbiMed IV-AL"). OrbiMed Capital GP IV LLC ("OrbiMed GP"), is the general partner of OrbiMed IV-AL. OrbiMed Advisors LLC ("OrbiMed Advisors"), a registered adviser under the Investment Advisers Act of 1940, as amended, is the managing member of OrbiMed GP. By virtue of such relationships, OrbiMed GP and OrbiMed Advisors may be deemed to have voting and investment power over the securities held by OrbiMed IV-AL and as a result may be deemed to have beneficial ownership over such securities. The Reporting Person is a member of OrbiMed Advisors. ( 3 )Each of OrbiMed GP, OrbiMed Capital LLC ("OrbiMed Capital"), OrbiMed Advisors and the Reporting Person disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its or his pecuniary interest therein, if any. This report on Form 3 shall not be deemed an admission that any of the reporting persons is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose. ( 4 )The Shares are held of record by OrbiMed Private Investments IV-AL (Feeder), LP ("OrbiMed IV-AL (Feeder)"). OrbiMed GP is the general partner of OrbiMed IV-AL (Feeder). OrbiMed Advisors, a registered adviser under the Investment Advisers Act of 1940, as amended, is the managing member of OrbiMed GP. By virtue of such relationships, OrbiMed GP and OrbiMed Advisors may be deemed to have voting and investment power over the securities held by OrbiMed IV-AL (Feeder) and as a result may be deemed to have beneficial ownership over such securities. The Reporting Person is a member of OrbiMed Advisors. ( 5 )The Shares are held of record by OrbiMed Partners Master Fund Limited ("OPM"). OrbiMed Capital, a registered investment adviser under the Investment Advisers Act, acts as the investment advisor to OPM. By virtue of such relationships, OrbiMed Capital may be deemed to have voting and investment power over the securities held by OPM and as a result may be deemed to have beneficial ownership over such securities.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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