[SCHEDULE 13G] Alto Neuroscience, Inc. SEC Filing

Rhea-AI Filing Summary

Alto Neuroscience (ANRO): Schedule 13G filed reporting a passive stake by Commodore Capital LP, Commodore Capital Master LP, Robert Egen Atkinson, and Michael Kramarz. The filers beneficially own 3,190,267 shares of common stock, representing 9.8% of the class.

The position includes 1,653,913 common shares and 1,536,354 shares issuable upon exercise of a pre-funded warrant, subject to a Beneficial Ownership Limitation. Ownership percentages are based on 30,908,892 shares outstanding as of October 20, 2025, plus the shares underlying the pre-funded warrant. The filers report shared voting and dispositive power over 3,190,267 shares and certify the securities were not acquired to change or influence control.

Insights

Equity ownership and disclosure analyst

Passive 9.8% stake, partly via pre-funded warrant.

Commodore Capital and affiliates disclosed beneficial ownership of 3,190,267 Alto Neuroscience shares, equal to 9.8%. The stake comprises 1,653,913 common shares plus 1,536,354 shares issuable from a pre-funded warrant, constrained by a Beneficial Ownership Limitation.

The filing cites an outstanding share count of 30,908,892 as of October 20, 2025, adding the warrant shares for the percentage calculation. The group reports shared voting and dispositive power and filed on a passive basis consistent with Schedule 13G certification.

Key variables include any changes to the outstanding share count and warrant exercises; actual impact depends on holder decisions and subsequent disclosures.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Alto Neuroscience, Inc.

(Name of Issuer)

Common Stock, $0.0001 par value per share

(Title of Class of Securities)

02157Q109

(CUSIP Number)

10/20/2025

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP No. 02157Q109

1

Names of Reporting Persons

Commodore Capital LP

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 3,190,267.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,190,267.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,190,267.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

9.8 %

12

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13G

CUSIP No. 02157Q109

1

Names of Reporting Persons

Commodore Capital Master LP

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 3,190,267.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,190,267.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,190,267.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

9.8 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP No. 02157Q109

1

Names of Reporting Persons

Robert Egen Atkinson

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 3,190,267.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,190,267.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,190,267.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

9.8 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

CUSIP No. 02157Q109

1

Names of Reporting Persons

Michael Kramarz

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 3,190,267.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,190,267.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,190,267.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

9.8 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Alto Neuroscience, Inc.
(b)	Address of issuer's principal executive offices: 650 Castro St, Suite 450, Mountain View, CALIFORNIA, 94041.
Item 2.
(a)	Name of person filing: Commodore Capital LP Commodore Capital Master LP Robert Egen Atkinson Michael Kramarz Each a "Filer."
(b)	Address or principal business office or, if none, residence: The address for Commodore Capital LP, Robert Egen Atkinson, and Michael Kramarz is 444 Madison Avenue, Floor 35, New York, NY 10022. The address for Commodore Capital Master LP is c/o Maples Corporate Services Limited, Ugland House, South Church Street, PO Box 309, Grand Cayman KY1-1104, Cayman Islands.
(c)	Citizenship: See Item 4 of the cover page for each Filer.
(d)	Title of class of securities: Common Stock, $0.0001 par value per share
(e)	CUSIP No.: 02157Q109
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: See Item 9 of the cover page for each Filer. This report on Schedule 13G is being filed by Commodore Capital LP (the "Firm"), Commodore Capital Master LP ("Commodore Master"), Michael Kramarz, and Robert Egen Atkinson. The Firm is the investment manager to Commodore Master. As of October 20, 2025, the Firm may be deemed to beneficially own an aggregate of 3,190,267 shares Common Stock, $0.0001 par value per share (the "Common Stock"), consisting of (i) 1,653,913 shares of the Common Stock and (ii) 1,536,354 shares of Common Stock each Filer has the right to acquire through the exercise of a pre-funded warrant ("Pre-Funded Warrant") of Alto Neuroscience, Inc. (the "Issuer"). The Firm, as the investment manager to Commodore Master, may be deemed to beneficially own these securities. Michael Kramarz and Robert Egen Atkinson are the managing partners of the Firm and exercise investment discretion with respect to these securities. Ownership percentages are based on 30,908,892 shares of Common Stock outstanding on October 20, 2025, as reported directly by the Issuer to the Firm, plus 1,536,354 shares of Common Stock which the Filers may acquire upon the exercise of the Pre-Funded Warrant, subject to the Beneficial Ownership Limitation.
(b)	Percent of class: See Item 11 of the cover page for each Filer.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: See Item 5 of the cover page for each Filer.
	(ii) Shared power to vote or to direct the vote: See Item 6 of the cover page for each Filer.
	(iii) Sole power to dispose or to direct the disposition of: See Item 7 of the cover page for each Filer.
	(iv) Shared power to dispose or to direct the disposition of: See Item 8 of the cover page for each Filer.
Item 5.	Ownership of 5 Percent or Less of a Class.
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Commodore Capital LP

Signature:	Michael Kramarz
Name/Title:	Managing Partner
Date:	10/27/2025

Commodore Capital Master LP

Signature:	Michael Kramarz
Name/Title:	Authorized Signatory
Date:	10/27/2025

Robert Egen Atkinson

Signature:	Robert Egen Atkinson
Name/Title:	Authorized Signatory
Date:	10/27/2025

Michael Kramarz

Signature:	Michael Kramarz
Name/Title:	Authorized Signatory
Date:	10/27/2025

Exhibit Information

Exhibit 1: Joint Filing Agreement

FAQ

What stake in ANRO did Commodore Capital report?

They reported beneficial ownership of 3,190,267 shares, or 9.8% of Alto Neuroscience’s common stock.

How is the 3,190,267-share position in ANRO composed?

It includes 1,653,913 common shares and 1,536,354 shares issuable upon exercise of a pre-funded warrant.

What share count was used to calculate ANRO ownership percentage?

Ownership is based on 30,908,892 shares outstanding as of October 20, 2025, plus the warrant shares.

Do the filers have voting and dispositive power over the ANRO shares?

Yes. They report shared voting and dispositive power over 3,190,267 shares and no sole power.

Is this a passive or activist filing for ANRO?

It is a Schedule 13G with a certification indicating the securities were not acquired to change or influence control.

Who are the reporting persons in this ANRO Schedule 13G?

Commodore Capital LP, Commodore Capital Master LP, Robert Egen Atkinson, and Michael Kramarz.