Sirenia Capital (ANRO) discloses 2.22M Alto Neuroscience shares under beneficial ownership

Rhea-AI Filing Summary

Sirenia Capital Management LP and Alex Silverstein report beneficial ownership of Alto Neuroscience, Inc. common stock. They collectively report 2,219,568 shares of Common Stock, including 787,043 shares issuable upon exercise of warrants, representing 6.2% of the class based on 35,093,940 shares outstanding as of May 8, 2026. Voting and dispositive power over these shares is shared, with no sole voting or dispositive power reported. SILV Fund, Ltd. has the right to receive dividends or sale proceeds for more than 5% of the outstanding Common Stock.

Key Figures

Beneficially owned shares: 2,219,568 shares Ownership percentage: 6.2% Warrant shares included: 787,043 shares +3 more

6 metrics

Beneficially owned shares 2,219,568 shares Shares of Alto Neuroscience Common Stock beneficially owned by the Reporting Persons

Ownership percentage 6.2% Percent of Alto Neuroscience Common Stock class beneficially owned

Warrant shares included 787,043 shares Common Stock issuable upon exercise of warrants held by Sirenia Funds

Shares outstanding baseline 35,093,940 shares Alto Neuroscience Common Stock outstanding as of May 8, 2026

Shared voting power 2,219,568 shares Shares over which the Reporting Persons have shared power to vote

Shared dispositive power 2,219,568 shares Shares over which the Reporting Persons have shared power to dispose

Key Terms

beneficial owner, shared voting power, shared dispositive power, Investment Company Act of 1940, +1 more

5 terms

beneficial owner regulatory

"for the purposes of Section 13 of the Securities Exchange Act of 1934, the beneficial owner of the securities"

A beneficial owner is the person who ultimately owns or controls a financial asset or property, even if their name isn't directly on official documents. Think of it like someone who secretly holds the keys to a safe deposit box—others may appear to have access, but the true owner is the one who benefits from what's inside. Identifying beneficial owners helps ensure transparency and prevent illegal activities like money laundering or fraud.

shared voting power financial

"Shared Voting Power 2,219,568.00"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

shared dispositive power financial

"Shared Dispositive Power 2,219,568.00"

Investment Company Act of 1940 regulatory

"A listing of the shareholders of an investment company registered under the Investment Company Act of 1940"

A U.S. federal law that sets the rulebook for pooled investment vehicles such as mutual funds, exchange-traded funds and similar money managers, requiring them to register with regulators, disclose holdings and fees, limit conflicts of interest, and follow governance standards. It matters to investors because these protections and transparency rules act like a referee and scoreboard, helping people compare funds, trust that managers follow fair practices, and spot hidden costs or risks.

Schedule 13G regulatory

"This statement is filed by... for the purposes of Section 13 of the Securities Exchange Act of 1934"

A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.

FAQ

What percentage of Alto Neuroscience (ANRO) does Sirenia Capital Management report owning?

Sirenia Capital Management and Alex Silverstein report beneficial ownership of 6.2% of Alto Neuroscience’s Common Stock. This is based on 35,093,940 shares outstanding as of May 8, 2026, and includes shares issuable upon exercise of warrants.

How many Alto Neuroscience (ANRO) shares does Sirenia Capital Management beneficially own?

They report beneficial ownership of 2,219,568 shares of Alto Neuroscience Common Stock. This total includes both currently held shares and 787,043 shares that are issuable upon exercise of warrants held by Sirenia-managed funds.

What portion of Sirenia Capital’s Alto Neuroscience (ANRO) position comes from warrants?

Sirenia’s reported position includes 787,043 shares of Alto Neuroscience Common Stock issuable upon exercise of warrants. These warrant-related shares form part of the total 2,219,568 shares beneficially owned for Schedule 13G reporting purposes.

Who has voting and dispositive power over Sirenia’s Alto Neuroscience (ANRO) shares?

Sirenia Capital Management and Alex Silverstein report shared voting power and shared dispositive power over 2,219,568 shares. They report no sole voting or sole dispositive power over any Alto Neuroscience Common Stock in this filing.

Which entity may receive dividends or sale proceeds from Alto Neuroscience (ANRO) shares held by Sirenia?

The filing states that SILV Fund, Ltd. has the right to receive, or direct the receipt of, dividends or sale proceeds from more than 5% of Alto Neuroscience’s outstanding Common Stock associated with this reported position.

On what share count is Sirenia’s 6.2% Alto Neuroscience (ANRO) ownership based?

The 6.2% ownership figure is calculated using 35,093,940 shares of Alto Neuroscience Common Stock outstanding as of May 8, 2026, as reported in Alto Neuroscience’s Form 10-Q for the quarter ended March 31, 2026.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 08/14/2026 - 08:31 AM Accepted by SEC EDGAR 08/14/2026 - 08:30 AM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

Alto Neuroscience, Inc.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

02157Q109

(CUSIP Number)

06/30/2026

(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)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 02157Q109

1

Names of Reporting Persons

Sirenia Capital Management 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 2,219,568.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,219,568.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,219,568.00

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)

6.2 %

12

Type of Reporting Person (See Instructions)

IA, PN

Comment for Type of Reporting Person: Includes 787,043 shares of Common Stock (as defined in Item 2(a)) issuable upon exercise of warrants.

SCHEDULE 13G

CUSIP Number(s): 02157Q109

1

Names of Reporting Persons

Alex Silverstein

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 2,219,568.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,219,568.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,219,568.00

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)

6.2 %

12

Type of Reporting Person (See Instructions)

HC, IN

Comment for Type of Reporting Person: Includes 787,043 shares of Common Stock issuable upon exercise of warrants.

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, CA 94041
Item 2.
(a)	Name of person filing: This statement is filed by: (i) Sirenia Capital Management LP ("Sirenia") with respect to the common stock, par value $0.0001 per share ("Common Stock"), of Alto Neuroscience, Inc. (the "Issuer") held by, and issuable upon exercise of warrants held by, investment funds it manages (the "Sirenia Funds"); and (ii) Alex Silverstein ("Mr. Silverstein"), the managing member of Sirenia Capital Management GP LLC, the general partner of Sirenia, with respect to the Common Stock held by, and issuable upon exercise of warrants held by, the Sirenia Funds. The foregoing persons are hereinafter sometimes collectively referred to as the "Reporting Persons." The filing of this statement should not be construed as an admission that any of the foregoing persons or any Reporting Person is, for the purposes of Section 13 of the Securities Exchange Act of 1934, the beneficial owner of the securities reported herein.
(b)	Address or principal business office or, if none, residence: The address of the principal business office of Sirenia and Mr. Silverstein is 1674 Meridian Avenue, Suite 320, Miami Beach, FL 33139.
(c)	Citizenship: Sirenia is a Delaware limited partnership. Mr. Silverstein is a United States citizen.
(d)	Title of class of securities: Common Stock, par value $0.0001 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: The information required by Item 4(a) is set forth in Row 9 of the cover page for each of the Reporting Persons and is incorporated herein by reference. The percentage set forth in this Schedule 13G is calculated based upon an aggregate of 35,093,940 shares of Common Stock outstanding as of May 8, 2026, as reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period of March 31, 2026, filed with the Securities and Exchange Commission on May 13, 2026, and assumes the exercise of the warrants held by the Sirenia Funds.
(b)	Percent of class: 6.2%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: The information required by Item 4(c)(i) is set forth in Row 5 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(ii) Shared power to vote or to direct the vote: The information required by Item 4(c)(ii) is set forth in Row 6 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(iii) Sole power to dispose or to direct the disposition of: The information required by Item 4(c)(iii) is set forth in Row 7 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(iv) Shared power to dispose or to direct the disposition of: The information required by Item 4(c)(iv) is set forth in Row 8 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. See Item 2(a). SILV Fund, Ltd. has the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, more than 5 percent of the outstanding Common Stock.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary. See Item 2(a) and Item 3.
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 acquired and are held in the ordinary course of business and 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.

Sirenia Capital Management LP

Signature:	/s/ Kolby Loft
Name/Title:	Kolby Loft, General Counsel & Chief Compliance Officer
Date:	08/14/2026

Alex Silverstein

Signature:	/s/ Alex Silverstein
Name/Title:	Alex Silverstein, individually
Date:	08/14/2026