SEC Filing Summary

Rosenthal Arnon, Chief Executive Officer of Alector, Inc., reported transactions on October 13-14, 2026. These transactions involved a stock option repricing, reducing the exercise price to $1.87 per share for certain options. Arnon acquired various amounts of employee stock options, with post-transaction shares ranging from 0 to 978,750 for different option series. Additionally, Arnon acquired 217,500 shares of Common Stock under a restricted stock unit award vesting quarterly starting December 1, 2026, resulting in a post-transaction total of 2,512,100 shares. Indirectly held shares in trusts and directly held shares also changed, with specific holdings detailed in footnotes.