Cabaletta Bio (CABA) grants 175,000 stock options to Chief Business Officer

Rhea-AI Filing Summary

Cabaletta Bio, Inc. reported that Chief Business Officer Arun Das received a grant of stock options. The award covers 175,000 options to buy Cabaletta Bio common stock at an exercise price of $0.00 per share, representing a compensatory equity grant rather than a market purchase.

According to the vesting terms, 25% of the shares underlying this option vest and become exercisable on March 1, 2027. The remaining options vest in twelve substantially equal quarterly installments after that date, as long as he continues in service through each vesting date.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Das Arun

Role Chief Business Officer

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (Right to Buy)	175,000	$0.00	--

Holdings After Transaction: Stock Option (Right to Buy) — 175,000 shares (Direct)

Footnotes (1)

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Form 4 Insider Transactions: What Each Field Means →

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).

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^*

Das Arun

(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 Business Officer

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		175,000		(1)	03/01/2036	Common Stock	175,000	$0.00	175,000	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 Arun Das?

Cabaletta Bio reported that Chief Business Officer Arun Das received a grant of 175,000 stock options. These options were awarded at an exercise price of $0.00 per share, reflecting an equity compensation grant instead of an open-market purchase of existing shares.

How many Cabaletta Bio (CABA) stock options were granted to Arun Das?

Arun Das was granted 175,000 stock options in Cabaletta Bio. This entire amount is reported as beneficially owned following the grant, subject to a multi-year vesting schedule tied to his continued service with the company in his executive role.

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

For Arun Das’s option grant, 25% of the underlying shares vest on March 1, 2027. The remaining 75% then vest in twelve substantially equal quarterly installments, provided he remains in service with Cabaletta Bio on each scheduled vesting date through the full vesting period.

Is Arun Das’s Cabaletta Bio (CABA) option grant an open-market stock purchase?

No, the transaction is a compensatory stock option grant, not an open-market purchase. The options were granted at an exercise price of $0.00 per share under his executive compensation, and may be exercised for shares only as they vest over time.

What role does Arun Das hold at Cabaletta Bio (CABA) in connection with this grant?

Arun Das serves as Chief Business Officer at Cabaletta Bio in connection with this option grant. His role as an executive officer explains why he received a sizable equity award with time-based vesting, aligning his potential future ownership with the company’s long-term performance.

When do Arun Das’s Cabaletta Bio (CABA) options start becoming exercisable?

The options for Arun Das begin vesting and becoming exercisable on March 1, 2027, when 25% of the underlying shares vest. After that date, additional portions vest in twelve substantially equal quarterly installments, assuming continued service with Cabaletta Bio throughout the vesting timeline.