Steven Nichtberger reports 1.685M exercisable options in CABA stake

Rhea-AI Filing Summary

In this Schedule 13G/A, Steven Nichtberger reports beneficial ownership of 3,034,499 shares of Cabaletta Bio common stock, representing approximately 3.3% of the outstanding class. The total comprises 986,483 shares held directly (about 1.1%), 363,000 shares held by the 2017 Nichtberger Family Trust (about 0.4%), and 1,685,016 shares underlying options exercisable within 60 days (about 1.8%).

The filing states Dr. Nichtberger has sole voting and dispositive power over all 3,034,499 shares. The reported percentages were calculated using 91,451,899 outstanding shares plus the exercisable options deemed outstanding under SEC rules. The filing indicates no shared voting power, no group affiliation, and no holdings reported on behalf of others.

Insights

Securities Analyst

TL;DR: Reports beneficial ownership of 3,034,499 shares (3.3%), including 1,685,016 exercisable options.

The filing discloses a modest, non-controlling stake in Cabaletta Bio equal to approximately 3.3% of the class when exercisable options are included. The breakdown is explicit: direct holdings, family trust holdings, and a substantial tranche of options exercisable within 60 days that SEC rules treat as outstanding for percentage calculations. The reporter claims sole voting and dispositive power, which means he controls voting and disposition of the disclosed shares. There is no indication of group affiliation or shared control in the filing.

Corporate Governance Expert

TL;DR: Holder reports sole authority over 3,034,499 shares and serves as trustee for the family trust holding part of the stake.

The Schedule explicitly states Dr. Nichtberger is a trustee of the 2017 Nichtberger Family Trust and that the trust holds 363,000 shares. The filing reports no shared voting or dispositive power and marks group-related items as not applicable. From a governance perspective, the filing documents clear, concentrated authority over the disclosed position but does not show an ownership level that would trigger mandatory Schedule 13D control presumptions.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 3)

Cabaletta Bio, Inc.

(Name of Issuer)

Common Stock, par value $0.00001 per share

(Title of Class of Securities)

12674W109

(CUSIP Number)

06/30/2025

(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. 12674W109

1

Names of Reporting Persons

Nichtberger Steven

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 3,034,499.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 3,034,499.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,034,499.00

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)

3.3 %

12

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Cabaletta Bio, Inc.
(b)	Address of issuer's principal executive offices: 2929 ARCH STREET, SUITE 600, PHILADELPHIA, PENNSYLVANIA, 19104.
Item 2.
(a)	Name of person filing: This Schedule 13G is being filed on behalf of Steven Nichtberger (the "Reporting Person").
(b)	Address or principal business office or, if none, residence: c/o Cabaletta Bio, Inc. 2929 Arch Street, Suite 600 Philadelphia, PA 19104
(c)	Citizenship: United States of America
(d)	Title of class of securities: Common Stock, par value $0.00001 per share
(e)	CUSIP No.: 12674W109
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: As of June 30, 2025, the Reporting Person beneficially owned an aggregate of 3,034,499 shares of the Common Stock, par value $0.00001 per share ("Common Stock") of Cabaletta Bio, Inc. (the "Issuer"), representing approximately 3.3% of the outstanding Common Stock, consisting of (a) 986,483 shares of Common Stock held directly by Dr. Nichtberger, representing approximately 1.1% of the outstanding Common Stock, (b) 363,000 shares of Common Stock held directly by the 2017 Nichtberger Family Trust, representing approximately 0.4% of the outstanding Common Stock, and (c) 1,685,016 shares of Common Stock underlying options held directly by Dr. Nichtberger that are exercisable within 60 days of June 30, 2025, representing approximately 1.8% of the outstanding Common Stock. Dr. Nichtberger is a trustee of the 2017 Nichtberger Family Trust.
(b)	Percent of class: The foregoing percentages were calculated based on (a) 91,451,899 shares of the Issuer's Common Stock outstanding as of June 30, 2025 plus (b) 1,685,016 shares of Common Stock underlying stock options held by Dr. Nichtberger that are exercisable within 60 days of June 30, 2025, which are deemed outstanding pursuant to SEC Rule 13-3(d)(1)(i).
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 3,034,499
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 3,034,499
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	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:
	Not Applicable

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.

Nichtberger Steven

Signature:	/s/ Steven Nichtberger
Name/Title:	Steven Nichtberger
Date:	08/11/2025

FAQ

How many CABA shares does Steven Nichtberger beneficially own?

The filing reports 3,034,499 shares beneficially owned, representing approximately 3.3% of the class.

What is the ownership breakdown reported for CABA?

The total includes 986,483 shares held directly, 363,000 shares held by the 2017 Nichtberger Family Trust, and 1,685,016 shares underlying options exercisable within 60 days.

Does Steven Nichtberger have voting power over these CABA shares?

Yes. The filing states he has sole voting and sole dispositive power over all 3,034,499 shares.

Are the options included in the ownership percentage for CABA?

Yes. The filing indicates percentages were calculated using 91,451,899 outstanding shares plus the 1,685,016 exercisable options, which are deemed outstanding under SEC rules.

Is this ownership held on behalf of others or as part of a group?

No. The filing indicates no holdings on behalf of another person and lists group-related items as Not Applicable.