X0609 4 2026-09-29 0 0001999480 Alto Neuroscience, Inc. ANRO 0002009130 Smith Nicholas Conrad false C/O ALTO NEUROSCIENCE, INC. 650 CASTRO STREET, SUITE 450 MOUNTAIN VIEW CA 94041 0 1 0 0 PRESIDENT AND CFO 0 Common Stock 2026-09-29 4 M 0 56455 2.35 A 80515 D Common Stock 2026-09-29 4 M 0 54375 2.35 A 134890 D Common Stock 2026-09-29 4 S 0 110830 26.5826 D 24060 D Common Stock 2026-09-30 4 M 0 24056 2.35 A 48116 D Common Stock 2026-09-30 4 S 0 23170 25.7786 D 24946 D Common Stock 2026-09-30 4 S 0 886 26.87 D 24060 D Employee Stock Option (Right to Buy) 2.35 2026-09-29 4 M 0 56455 0 D 2033-12-19 Common Stock 56455 145874 D Employee Stock Option (Right to Buy) 2.35 2026-09-29 4 M 0 54375 0 D 2034-02-28 Common Stock 54375 35625 D Employee Stock Option (Right to Buy) 2.35 2026-09-30 4 M 0 24056 0 D 2033-12-19 Common Stock 24056 121818 D This transaction was pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on June 30, 2026. This price is a weighted average price. These securities were sold in multiple transactions at prices ranging from $26.5513 to $26.5902 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of securities sold at each separate price within the range set forth in this footnote. One-third (1/3rd) of the shares underlying the option vested upon the completion of the Issuer's initial public offering and two-thirds (2/3) of the shares underlying the option vested or shall vest over a period of four years. 25% of the shares underlying the time-based portion vested on December 20, 2024, and 1/48 of the shares underlying the time-based portion vested or shall vest on a monthly basis thereafter, subject to the Reporting Person's continuous service through such vesting date. 25% of the shares underlying the option vested on March 1, 2025, and one forty-eighth (1/48th) of the shares underlying the option vested or shall vest in monthly installments thereafter, subject to the Reporting Person's continuous service through each such vesting date. /s/ Erin R. McQuade, Attorney-in-Fact 2026-10-01