UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of

The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported)

January 29, 2020

Alector, Inc.

(Exact name of registrant as specified in its charter)

131 Oyster Point Blvd. Suite 600

South San Francisco, California 94080

(Address of principal executive offices, including zip code)

(415) 231-5660

(Registrant’s telephone number, including area code)

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☒

On January 29, 2020, Alector, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Morgan Stanley & Co. LLC, Goldman Sachs & Co. LLC, BofA Securities, Inc., and Cowen and Company, LLC, as representatives of the several underwriters named therein (collectively, the “Underwriters”), relating to the public offering of 8,350,000 shares of the Company’s common stock, par value $0.0001 per share (the “Common Stock”), at a price to the public of $25.00 per share (the “Offering”). The Company also granted the Underwriters an option to purchase up to 1,252,500 shares of the Company’s common stock at the public offering price, less underwriting discounts and commissions, which the Underwriters exercised in full on January 30, 2020.

The Underwriting Agreement contains customary representations, warranties and agreements by us, customary conditions to closing, indemnification obligations of the Company and the Underwriters, including for liabilities under the Securities Act of 1933, as amended, other obligations of the parties and termination provisions. The representations, warranties and covenants contained in the Underwriting Agreement were made only for purposes of such agreement and as of specific dates, were solely for the benefit of the parties to such agreement and may be subject to limitations agreed upon by such parties.

The Offering closed on February 3, 2020. The gross proceeds to the Company from the Offering were approximately $240.0 million, before deducting underwriting discounts and commissions and other estimated offering expenses payable by the Company. The Offering was made pursuant to the Company’s effective registration statements on Form S-1 (Registration Statement Nos. 333-236094 and 333-236159) and the related accompanying prospectus, in each case filed with the Securities and Exchange Commission.

The description of the Underwriting Agreement set forth above is qualified in its entirety by reference to the Underwriting Agreement, a copy of which is filed as Exhibit 1.1 hereto and is incorporated herein by reference.

On February 3, 2020, the Company issued a press release announcing the closing of the Offering. A copy of the press release is attached hereto as Exhibit 99.1.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date: February 4, 2020