– Gavel Steve (CIK 0002090785)

Cabaletta Bio (CABA) disclosed a Form 4 showing its Chief Commercial Officer received a grant of stock options to purchase 275,000 shares at an exercise price of $2.49 on October 13, 2025.

Rhea-AI Filing Summary

Cabaletta Bio (CABA) disclosed a Form 4 showing its Chief Commercial Officer received a grant of stock options to purchase 275,000 shares at an exercise price of $2.49 on October 13, 2025.

The option was granted under the company’s 2025 Inducement Plan pursuant to NASDAQ Listing Rule 5635(c)(4). It vests with 25% on October 13, 2026, and the remainder in twelve substantially equal quarterly installments thereafter, subject to continued service. The option expires on October 12, 2035. Following the grant, the reporting person holds 275,000 derivative securities directly.

Insider Trade Summary

Grant/Award: 275,000 shares

Grant/Award 1 txn

Insider Gavel Steve

Role CHIEF COMMERCIAL OFFICER

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (Right to Buy)	275,000	$0.00	$0.00

Holdings After Transaction: Stock Option (Right to Buy) — 275,000 contracts (Direct)

Footnotes (2)

1. F1. The stock option has been granted pursuant to the Cabaletta Bio, Inc. 2025 Inducement Plan as a material inducement to the Reporting Person's acceptance of employment with the Issuer in accordance with NASDAQ Listing Rule 5635(c)(4).
2. F2. 25% of the shares underlying this option shall vest and become exercisable on October 13, 2026, with the remainder vesting in twelve substantially equal quarterly installments thereafter, subject to the Reporting Person's continued service on each such vesting date.

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Accepted by SEC EDGAR 10/15/2025 - 12:00 AM EDT Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person^*

Gavel Steve

(Last) (First) (Middle)

C/O CABALETTA BIO, INC.

2929 ARCH STREET, SUITE 600

(Street)

PHILADELPHIA PA 19104

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Cabaletta Bio, Inc. [ CABA ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	CHIEF COMMERCIAL OFFICER

3. Date of Earliest Transaction (Month/Day/Year)
10/13/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option (Right to Buy)	$2.49	10/13/2025		A		275,000(1)		(2)	10/12/2035	Common Stock	275,000	$0.00	275,000	D

Explanation of Responses:

1. The stock option has been granted pursuant to the Cabaletta Bio, Inc. 2025 Inducement Plan as a material inducement to the Reporting Person's acceptance of employment with the Issuer in accordance with NASDAQ Listing Rule 5635(c)(4).

2. 25% of the shares underlying this option shall vest and become exercisable on October 13, 2026, with the remainder vesting in twelve substantially equal quarterly installments thereafter, subject to the Reporting Person's continued service on each such vesting date.

	/s/ Michael Gerard, Attorney-in-Fact	10/15/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.