Alector, Inc. (0001653087) (Filer)

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): October 15, 2026

Alector, Inc.

(Exact name of Registrant as Specified in Its Charter)

Registrant’s Telephone Number, Including Area Code: (415) 231-5660

(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:

Securities registered pursuant to Section 12(b) of the Act:

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 October 15, 2026, Alector, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Morgan Stanley & Co. LLC and BTIG, LLC (collectively, the “Underwriters”), relating to the issuance and sale (the “Offering”) of 36,600,000 shares (the “Shares”) of the Company’s common stock, par value $0.0001 per share (the “Common Stock”), at an offering price of $2.05 per share. All of the Shares in the Offering are being sold by the Company.

The gross proceeds from the Offering are expected to be $75,030,000.00 before deducting underwriting discounts and commissions and other offering expenses payable by the Company. The Offering is expected to close on October 19, 2026, subject to the satisfaction of customary closing conditions.

The Underwriting Agreement contains customary representations, warranties and agreements by the Company, 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 is being made pursuant to the Company’s effective registration statement on Form S-3 (File No. 333-294241) (the “Registration Statement”) and a related prospectus and prospectus supplement, in each case filed with the Securities and Exchange Commission.

The foregoing descriptions of the terms of the Underwriting Agreement do not purport to be complete and are each qualified in their entirety by reference to the Underwriting Agreement, which is filed as Exhibit 1.1 hereto and is incorporated herein by reference.

A copy of the opinion of Wilson Sonsini Goodrich & Rosati, P.C. relating to the validity of the Shares is filed as Exhibit 5.1 hereto and is incorporated by reference into the Registration Statement.

A copy of the press release announcing the pricing of the Offering is attached to this Current Report on Form 8-K as Exhibit 99.1.

Forward-Looking Statements

Certain of the statements made in this report are forward looking, such as those, among others, relating to the Company’s expectations regarding the timing and completion of the Offering. Actual results or developments may differ materially from those projected or implied in these forward-looking statements. Factors that may cause such a difference include risks and uncertainties related to completion of the public offering on the anticipated terms or at all, market conditions and the satisfaction of customary closing conditions related to the Offering. More information about the risks and uncertainties faced by the Company is contained under the caption “Risk Factors” in the Company’s Annual and Quarterly Reports on Form 10-K and 10-Q filed with the Securities and Exchange Commission (the “SEC”), and the Company’s future reports to be filed with the SEC. The Company disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

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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 thereunto duly authorized.

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