Cabaletta Bio (CABA) grants 225,000 stock options to its president

Rhea-AI Filing Summary

Cabaletta Bio, Inc. reported that President, Science & Tech. Gwendolyn Binder acquired a grant of 225,000 stock options on March 2, 2026. These options have a stated price of $0.00 per share and represent rights to buy Cabaletta Bio common stock in the future.

According to the vesting terms, 25% of the shares underlying this option vest and become exercisable on March 1, 2027, with the remaining options vesting in twelve substantially equal quarterly installments thereafter, contingent on her continued service on each vesting date.

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

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

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Binder Gwendolyn

(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)
	President, Science & Tech.

3. Date of Earliest Transaction (Month/Day/Year)
03/02/2026

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)	$3.3	03/02/2026		A		225,000		(1)	03/01/2036	Common Stock	225,000	$0.00	225,000	D

Explanation of Responses:

1. 25% of the shares underlying this option shall vest and become exercisable on March 1, 2027, with the remainder vesting in twelve substantially equal quarterly installments thereafter, subject to the reporting person's continued service on each such vesting date.

	By: /s/ Michael Gerard, as Attorney-in-Fact	03/02/2026
	** 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.

FAQ

What insider transaction did Cabaletta Bio (CABA) report for Gwendolyn Binder?

Cabaletta Bio reported that Gwendolyn Binder received a grant of 225,000 stock options. The options were awarded on March 2, 2026 and give her the right to buy Cabaletta Bio common stock in the future under specified vesting conditions.

Is the Cabaletta Bio (CABA) Form 4 transaction a stock purchase or a grant?

The Form 4 transaction is a grant of stock options, not an open-market stock purchase. It is coded as an acquisition (Code A), reflecting a grant, award, or other acquisition of derivative securities provided as part of her compensation package.

How many stock options did Gwendolyn Binder receive from Cabaletta Bio (CABA)?

Gwendolyn Binder received 225,000 stock options from Cabaletta Bio. These options are described as “Stock Option (Right to Buy)” and, after this grant, her directly held derivative position reported in this award totals 225,000 options, subject to the vesting schedule disclosed.

What is the vesting schedule for Gwendolyn Binder’s Cabaletta Bio (CABA) stock options?

Twenty-five percent of the options vest and become exercisable on March 1, 2027. The remaining options vest in twelve substantially equal quarterly installments after that date, and each vesting installment requires her continued service with the company on the applicable vesting date.

What does the $0.00 price per share mean in the Cabaletta Bio (CABA) Form 4?

The Form 4 lists a transaction price of $0.00 per share because this entry reflects the grant of stock options, not an open-market trade. The reported figure indicates there was no cash paid in this grant transaction itself as disclosed.