SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 7)

Alector, Inc.

(Name of Issuer)

Common Stock, $0.0001 par value per share

(Title of Class of Securities)

014442107

(CUSIP Number)

03/31/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP Number(s):

014442107

Names of Reporting Persons

Polaris Venture Partners VI, L.P.

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 498,468.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 498,468.00
8	Shared Dispositive Power 0.00

Aggregate Amount Beneficially Owned by Each Reporting Person

498,468.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

0.5 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person: All shares are held of record by PVP VI (as defined in Item 2(a) of the Original Schedule 13G (as defined below)). PVM VI (as defined in Item 2(a) of the Original Schedule 13G), the general partner of PVP VI, may be deemed to have voting, investment and dispositive power with respect to these securities. David Barrett, Brian Chee, Jonathan A. Flint, Terrance G. McGuire, Amir Nashat, and Bryce Youngren are the managing members of PVM VI and may each be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 11 is based on 110,362,581 shares of the Issuer's common stock ("Common Stock") outstanding as of February 20, 2026, as set forth in the Issuer's annual report on Form 10-K for the year ended December 31, 2026, filed with the United States Securities and Exchange Commission (the "Commission") on February 25, 2026 (the "Form 10-K").

SCHEDULE 13G

CUSIP Number(s):

014442107

Names of Reporting Persons

Polaris Venture Partners Founders' Fund VI, L.P.

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 267,979.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 267,979.00
8	Shared Dispositive Power 0.00

Aggregate Amount Beneficially Owned by Each Reporting Person

267,979.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

0.2 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person: All shares are held of record by PVPFF VI (as defined in Item 2(a) of the Original Schedule 13G). PVM VI, the general partner of PVPFF VI, may be deemed to have voting, investment and dispositive power with respect to these securities. David Barrett, Brian Chee, Jonathan A. Flint, Terrance G. McGuire, Amir Nashat, and Bryce Youngren are the managing members of PVM VI and may each be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 11 is based on 110,362,581 shares of Common Stock outstanding as of February 20, 2026, as set forth in the Form 10-K.

SCHEDULE 13G

CUSIP Number(s):

014442107

Names of Reporting Persons

Polaris Venture Partners VI (AIV), L.P.

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 3,280,842.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 3,280,842.00
8	Shared Dispositive Power 0.00

Aggregate Amount Beneficially Owned by Each Reporting Person

3,280,842.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

3.0 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person: All shares are held of record by PVP VI (AIV) (as defined in Item 2(a) of the Original Schedule 13G). PVM VI, the general partner of PVP VI (AIV), may be deemed to have voting, investment and dispositive power with respect to these securities. David Barrett, Brian Chee, Jonathan A. Flint, Terrance G. McGuire, Amir Nashat, and Bryce Youngren are the managing members of PVM VI and may each be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 11 is based on 110,362,581 shares of Common Stock outstanding as of February 20, 2026, as set forth in the Form 10-K.

SCHEDULE 13G

CUSIP Number(s):

014442107

Names of Reporting Persons

Polaris Venture Partners VI (AIV-B), L.P.

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 806,528.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 806,528.00
8	Shared Dispositive Power 0.00

Aggregate Amount Beneficially Owned by Each Reporting Person

806,528.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

0.7 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person: All shares are held of record by PVP VI (AIV-B) (as defined in Item 2(a) of the Original Schedule 13G). PVM VI, the general partner of PVP VI (AIV-B), may be deemed to have voting, investment and dispositive power with respect to these securities. David Barrett, Brian Chee, Jonathan A. Flint, Terrance G. McGuire, Amir Nashat, and Bryce Youngren are the managing members of PVM VI and may each be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 11 is based on 110,362,581 shares of Common Stock outstanding as of February 20, 2026, as set forth in the Form 10-K.

SCHEDULE 13G

CUSIP Number(s):

014442107

Names of Reporting Persons

Polaris Venture Management Co VI, L.L.C.

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 4,853,817.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 4,853,817.00

Aggregate Amount Beneficially Owned by Each Reporting Person

4,853,817.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

4.4 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person: The shares reported in Rows 6 and 8 consist of (i) 498,468 shares held of record by PVP VI, (ii) 267,979 shares held of record by PVPFF VI, (iii) 3,280,842 shares held of record by PVP VI (AIV) and (iv) 806,528 shares held of record by PVP VI (AIV-B). PVM VI, the general partner of each of PVP VI, PVPFF VI, PVP VI (AIV) and PVP VI (AIV-B), may be deemed to have voting, investment and dispositive power with respect to these securities. David Barrett, Brian Chee, Jonathan A. Flint, Terrance G. McGuire, Amir Nashat, and Bryce Youngren are the managing members of PVM VI and may each be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 11 is based on 110,362,581 shares of Common Stock outstanding as of February 20, 2026, as set forth in the Form 10-K.

SCHEDULE 13G

CUSIP Number(s):

014442107

Names of Reporting Persons

David Barrett

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 4,853,817.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 4,853,817.00

Aggregate Amount Beneficially Owned by Each Reporting Person

4,853,817.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

4.4 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP Number(s):

014442107

Names of Reporting Persons

Brian Chee

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 4,853,817.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 4,853,817.00

Aggregate Amount Beneficially Owned by Each Reporting Person

4,853,817.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

4.4 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP Number(s):

014442107

Names of Reporting Persons

Jonathan A. Flint

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 39,124.00
6	Shared Voting Power 4,853,817.00
7	Sole Dispositive Power 39,124.00
8	Shared Dispositive Power 4,853,817.00

Aggregate Amount Beneficially Owned by Each Reporting Person

4,892,941.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

4.4 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person: The shares reported in Rows 5 and 7 are held directly by Jonathan A. Flint. The shares reported in Rows 6 and 8 consist of (i) 498,468 shares held of record by PVP VI, (ii) 267,979 shares held of record by PVPFF VI, (iii) 3,280,842 shares held of record by PVP VI (AIV) and (iv) 806,528 shares held of record by PVP VI (AIV-B). PVM VI, the general partner of each of PVP VI, PVPFF VI, PVP VI (AIV) and PVP VI (AIV-B), may be deemed to have voting, investment and dispositive power with respect to these securities. David Barrett, Brian Chee, Jonathan A. Flint, Terrance G. McGuire, Amir Nashat, and Bryce Youngren are the managing members of PVM VI and may each be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 11 is based on 110,362,581 shares of Common Stock outstanding as of February 20, 2026, as set forth in the Form 10-K.

SCHEDULE 13G

CUSIP Number(s):

014442107

Names of Reporting Persons

Terrance G. McGuire

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 319,682.00
6	Shared Voting Power 4,853,817.00
7	Sole Dispositive Power 319,682.00
8	Shared Dispositive Power 4,853,817.00

Aggregate Amount Beneficially Owned by Each Reporting Person

5,173,499.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

4.7 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person: The shares reported in Rows 5 and 7 consist of (i) 96,435 shares held directly by Terrance G. McGuire, (ii) 196,997 shares held by McGuire Family Trust, and (iii) 26,250 shares consist of restricted stock units that have been granted to Terrance G. McGuire in his capacity as a former director of the Issuer. Terrance G. McGuire is the donor of the McGuire Family Trust and may be deemed to share voting, investment and dispositive power with respect to the shares held by the McGuire Family Trust. The shares reported in Rows 6 and 8 consist of (i) 498,468 shares held of record by PVP VI, (ii) 267,979 shares held of record by PVPFF VI (iii) 3,280,842 shares held of record by PVP VI (AIV) and (iv) 806,528 shares held of record by PVP VI (AIV-B). PVM VI, the general partner of each of PVP VI, PVPFF VI, PVP VI (AIV) and PVP VI (AIV-B), may be deemed to have voting, investment and dispositive power with respect to these securities. David Barrett, Brian Chee, Jonathan A. Flint, Terrance G. McGuire, Amir Nashat, and Bryce Youngren are the managing members of PVM VI and may each be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 11 is based on 110,388,831 shares of Common Stock, calculated as follows: (i) 26,250 shares that represent restricted stock units that have been granted to Mr. McGuire in his capacity as a former director of the Issuer plus (ii) 110,362,581 shares of Common Stock outstanding as of February 20, 2026, as set forth in the Form 10-K.

SCHEDULE 13G

CUSIP Number(s):

014442107

Names of Reporting Persons

Amir Nashat

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 131,332.00
6	Shared Voting Power 4,853,817.00
7	Sole Dispositive Power 131,332.00
8	Shared Dispositive Power 4,853,817.00

Aggregate Amount Beneficially Owned by Each Reporting Person

4,985,149.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

4.5 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person: The shares reported in Rows 5 and 7 are held directly by Amir Nashat. The shares reported in Rows 6 and 8 consist of (i) 498,468 shares held of record by PVP VI, (ii) 267,979 shares held of record by PVPFF VI, (iii) 3,280,842 shares held of record by PVP VI (AIV) and (iv) 806,528 shares held of record by PVP VI (AIV-B). PVM VI, the general partner of each of PVP VI, PVPFF VI, PVP VI (AIV) and PVP VI (AIV-B), may be deemed to have voting, investment and dispositive power with respect to these securities. David Barrett, Brian Chee, Jonathan A. Flint, Terrance G. McGuire, Amir Nashat, and Bryce Youngren are the managing members of PVM VI and may each be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 11 is based on 110,362,581 shares of Common Stock outstanding as of February 20, 2026, as set forth in the Form 10-K.

SCHEDULE 13G

CUSIP Number(s):

014442107

Names of Reporting Persons

Bryce Youngren

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 11,864.00
6	Shared Voting Power 4,853,817.00
7	Sole Dispositive Power 11,864.00
8	Shared Dispositive Power 4,853,817.00

Aggregate Amount Beneficially Owned by Each Reporting Person

4,865,681.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

4.4 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person: The shares reported in Rows 5 and 7 are held directly by Bryce Youngren. The shares reported in Rows 6 and 8 consist of (i) 498,468 shares held of record by PVP VI, (ii) 267,979 shares held of record by PVPFF VI, (iii) 3,280,842 shares held of record by PVP VI (AIV) and (iv) 806,528 shares held of record by PVP VI (AIV-B). PVM VI, the general partner of each of PVP VI, PVPFF VI, PVP VI (AIV) and PVP VI (AIV-B), may be deemed to have voting, investment and dispositive power with respect to these securities. David Barrett, Brian Chee, Jonathan A. Flint, Terrance G. McGuire, Amir Nashat, and Bryce Youngren are the managing members of PVM VI and may each be deemed to share voting, investment and dispositive power with respect to these securities. The percentage in Row 11 is based on 110,362,581 shares of Common Stock outstanding as of February 20, 2026, as set forth in the Form 10-K.

SCHEDULE 13G

Item 1.

(a)

Name of issuer:

Alector, Inc.

(b)

Address of issuer's principal executive offices:

131 OYSTER POINT BLVD., SUITE 600, SOUTH SAN FRANCISCO, CA, 94080

Item 2.

(a)

Name of person filing:

This Amendment No. 7 (this "Amendment") amends and supplements the Schedule 13G initially filed with the Commission on February 12, 2020, as amended by Amendment No. 1 filed with the Commission on February 12, 2021, Amendment No. 2 filed with the Commission on February 11, 2022, Amendment No. 3 filed with the Commission on February 7, 2023, Amendment No. 4 filed with the Commission on February 9, 2024, Amendment No. 5 filed with the Commission on November 12, 2024, and Amendment No. 6 filed with the Commission on November 13, 2025 (collectively, the "Original Schedule 13G"). Only those items that are hereby reported are amended; all other items reported in the Original Schedule 13G remain unchanged. Information given in response to each item shall be deemed incorporated by reference in all other items, as applicable. Capitalized terms not defined in this Amendment have the meanings ascribed to them in the Original Schedule 13G. The following information in Item 4 with respect to the ownership of the Issuer's Common Stock by the Reporting Persons filing this Amendment No. 7 is provided as of April 30, 2026. Each of the Reporting Persons disclaims beneficial ownership of the shares of Common Stock reported in this Amendment No. 7, except for the shares, if any, such Reporting Person holds of record and to the extent of such Reporting Person's pecuniary interest therein.

(b)

Address or principal business office or, if none, residence:

(c)

Citizenship:

(d)

Title of class of securities:

Common Stock, $0.0001 par value per share

(e)

CUSIP No.:

014442107

Item 4.

Ownership

(a)

Amount beneficially owned:

See Row 9 of cover page for each Reporting Person and the corresponding footnotes.

(b)

Percent of class:

See Row 11 of cover page for each Reporting Person and the corresponding footnotes.

(c)

Number of shares as to which the person has:

(i) Sole power to vote or to direct the vote:

See Row 5 of cover page for each Reporting Person and the corresponding footnotes.

(ii) Shared power to vote or to direct the vote:

See Row 6 of cover page for each Reporting Person and the corresponding footnotes.

(iii) Sole power to dispose or to direct the disposition of:

See Row 7 of cover page for each Reporting Person and the corresponding footnotes.

(iv) Shared power to dispose or to direct the disposition of:

See Row 8 of cover page for each Reporting Person and the corresponding footnotes.

Item 5.

Ownership of 5 Percent or Less of a Class.

Ownership of 5 percent or less of a class

Item 10.

Certifications:

Not Applicable

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Polaris Venture Partners VI, L.P.

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett/ Authorized Signatory of Polaris Venture Management Co. VI, L.L.C., general partner of Polaris Venture Partners VI, L.P.
Date:	05/14/2026

Polaris Venture Partners Founders' Fund VI, L.P.

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett/ Authorized Signatory of Polaris Venture Management Co. VI, L.L.C., GP of Polaris Venture Partners Founders' Fund VI, L.P.
Date:	05/14/2026

Polaris Venture Partners VI (AIV), L.P.

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett/ Authorized Signatory of Polaris Venture Management Co. VI, L.L.C., general partner of Polaris Venture Partners VI (AIV), L.P.
Date:	05/14/2026

Polaris Venture Partners VI (AIV-B), L.P.

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett/ Authorized Signatory of Polaris Venture Management Co. VI, L.L.C., general partner of Polaris Venture Partners VI (AIV-B), L.P.
Date:	05/14/2026

Polaris Venture Management Co VI, L.L.C.

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett/ Authorized Signatory*
Date:	05/14/2026

David Barrett

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett/ Attorney-In-Fact
Date:	05/14/2026

Brian Chee

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett/ Attorney-In-Fact
Date:	05/14/2026

Jonathan A. Flint

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett/ Attorney-In-Fact
Date:	05/14/2026

Terrance G. McGuire

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett/ Attorney-In-Fact
Date:	05/14/2026

Amir Nashat

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett/ Attorney-In-Fact
Date:	05/14/2026

Bryce Youngren

Signature:	/s/ Lauren Crockett
Name/Title:	Lauren Crockett/ Attorney-In-Fact
Date:	05/14/2026

Comments accompanying signature: This Schedule 13G was executed pursuant to a Power of Attorney. Note that copies of the applicable Power of Attorney are already on file with the appropriate agencies.

Amendment: SEC Form SCHEDULE 13G/A filed by Alector Inc.