RA Capital Management, L.P., Peter Kolchinsky, Rajeev Shah, and RA Capital Healthcare Fund, L.P. filed a Schedule 13G with the SEC on October 26, 2026, disclosing beneficial ownership of 7,500,000 shares of Alector, Inc. common stock following a public offering that closed on October 19, 2026.

Key Highlights

  • Shares reported: Each of the four reporting persons listed 7,500,000 shares of Alector, Inc. common stock beneficially owned in aggregate.
  • Percent of class: The stake represents 5.1% of Alector's outstanding common stock, according to the filing.
  • Direct holder: RA Capital Healthcare Fund, L.P. directly holds the 7,500,000 shares; RA Capital Management, L.P. serves as investment adviser and exercises sole power to vote and dispose of those shares.
  • Triggering event: The filing was triggered by a public offering of equity securities by Alector that closed on October 19, 2026, in which 36,600,000 shares of common stock were issued.
  • Share count basis: The 5.1% figure is based on 111,656,919 shares outstanding as of July 31, 2026, plus the 36,600,000 shares issued in the October 19, 2026 offering.
  • Voting and dispositive power: All four reporting persons reported 0 sole voting power and 0 sole dispositive power, with shared voting and shared dispositive power each listed at 7,500,000 shares.
  • Disclaimers: The filing states that the reporting persons "expressly disclaim status as a 'group'" and that RA Capital, Dr. Kolchinsky, and Mr. Shah disclaim beneficial ownership other than for purposes of determining their obligations under Section 13(d).

RA Capital's 5.1% Position in Alector After October 2026 Equity Offering

According to the Schedule 13G filed October 26, 2026, four related reporting persons disclosed a combined beneficial ownership position of 7,500,000 shares of Alector, Inc. (NASDAQ:ALEC) common stock, par value $0.0001 per share (CUSIP 014442107). The filing identifies the reporting persons as RA Capital Management, L.P. ("RA Capital"), a Delaware limited partnership; RA Capital Healthcare Fund, L.P. (the "Fund"), also a Delaware limited partnership; Peter Kolchinsky ("Dr. Kolchinsky"), a United States citizen; and Rajeev Shah ("Mr. Shah"), a United States citizen. All four share a principal business address of c/o RA Capital Management, L.P., 200 Berkeley Street, 18th Floor, Boston, MA 02116.

The filing explains that the Fund directly holds the 7,500,000 shares. RA Capital serves as investment adviser to the Fund and, according to the filing, "may be deemed a beneficial owner, for purposes of Section 13(d) of the Act, of any securities of the Issuer held by the Fund." The Fund has delegated to RA Capital the sole power to vote and dispose of all securities in its portfolio, and the filing states that this delegation cannot be revoked on less than 61 days' notice. Dr. Kolchinsky and Mr. Shah are described as the controlling persons of RA Capital Management GP, LLC, the general partner of RA Capital, and may therefore also be deemed beneficial owners under Section 13(d).

The percentage calculation is based on 111,656,919 shares outstanding as of July 31, 2026, as reported in Alector's Form 10-Q filed August 6, 2026, plus 36,600,000 shares issued in Alector's public equity offering that closed October 19, 2026, as reported in Alector's Form 8-K filed October 16, 2026. That combined share base produces the reported 5.1% ownership figure. The event date that required this filing is listed as October 19, 2026.

What Was Disclosed

Four affiliated reporting persons, led by RA Capital Management, L.P., disclosed shared beneficial ownership of 7,500,000 shares of Alector, Inc. common stock, equal to 5.1% of the class, triggered by Alector's public equity offering closing October 19, 2026.