Alector, Inc. — Director's Dealing 2019

Feb 6, 2019

SEC Form 3 — Initial Statement of Beneficial Ownership

Issuer: Alector, Inc. (ALEC)
CIK: 0001653087
Period of Report: 2019-02-06

Reporting Person: Polaris Venture Management Co. VI, L.L.C. (10% Owner)
Reporting Person: Polaris Venture Partners VI (AIV), L.P. (10% Owner)
Reporting Person: Polaris Venture Partners Founders' Fund VI, L.P. (10% Owner)
Reporting Person: PVP VI (AIV) Feeder Corp. Holding Partnership, L.P. (10% Owner)
Reporting Person: Polaris Venture Partners VI, L.P. (10% Owner)

Holdings (Derivative)

Security	Exercise Price	Expiration	Underlying	Shares	Ownership
Series A-1 Preferred Stock	$		Common Stock (500000)		Indirect
Series A-2 Preferred Stock	$		Common Stock (5274725)		Indirect
Series B Preferred Stock	$		Common Stock (2500000)		Indirect
Series C Preferred Stock	$		Common Stock (2808989)		Indirect
Series D Preferred Stock	$		Common Stock (1246883)		Indirect
Series E Preferred Stock	$		Common Stock (527597)		Indirect

Footnotes

F1: 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 is convertible into Common Stock on a one-for-one basis into the number of shares of Common Stock shown in Column 3 at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering without payment of further consideration. The shares have no expiration date.

F2: 27,606 shares are held by Polaris Venture Partners Founders' Fund VI, L.P ("PVPFF VI"), 379,174 shares are held by Polaris Venture Partners VI (AIV), L.P. ("PVP VI AIV") and 93,220 shares are held by PVP VI (AIV) Feeder Corp. Holding Partnership, L.P. ("PVP VI Feeder" and, together with PVP VI AIV, PVPFF VI, and Polaris Venture Partners VI, L.P. ("PVP VI"), the "Polaris Funds"). The general partner of each of the Polaris Funds is Polaris Venture Management Co. VI, L.L.C. ("PVM"). PVM disclaims beneficial ownership of the securities held by the Polaris Funds, and this report shall not be deemed an admission that PVM is the beneficial owner of such securities, except to the extent of its pecuniary interest therein, if any.

F3: 291,223 shares are held by PVPFF VI, 4,000,075 shares are held by PVP VI AIV and 983,427 shares are held by PVP VI Feeder. PVM disclaims beneficial ownership of the securities held by the Polaris Funds, and this report shall not be deemed an admission that PVM is the beneficial owner of such securities, except to the extent of its pecuniary interest therein, if any.

F4: 138,030 shares are held by PVPFF VI, 1,895,867 shares are held by PVP VI AIV and 466,103 shares are held by PVP VI Feeder. PVM disclaims beneficial ownership of the securities held by the Polaris Funds, and this report shall not be deemed an admission that PVM is the beneficial owner of such securities, except to the extent of its pecuniary interest therein, if any.

F5: 155,087 shares are held by PVPFF VI, 2,130,190 shares are held by PVP VI AIV and 523,712 shares are held by PVP VI Feeder. PVM disclaims beneficial ownership of the securities held by the Polaris Funds, and this report shall not be deemed an admission that PVM is the beneficial owner of such securities, except to the extent of its pecuniary interest therein, if any.

F6: 68,842 shares are held by PVPFF VI, 945,571 shares are held by PVP VI AIV and 232,470 shares are held by PVP VI Feeder. PVM disclaims beneficial ownership of the securities held by the Polaris Funds, and this report shall not be deemed an admission that PVM is the beneficial owner of such securities, except to the extent of its pecuniary interest therein, if any.

F7: 29,129 shares are held by PVPFF VI and 498,468 shares are held by PVP VI. PVM disclaims beneficial ownership of the securities held by the Polaris Funds, and this report shall not be deemed an admission that PVM is the beneficial owner of such securities, except to the extent of its pecuniary interest therein, if any.