Cabaletta Bio director granted 22,000 stock options

Cabaletta Bio director Scott C. Brun received a grant of stock options covering 22,000 shares of common stock.

Rhea-AI Filing Summary

Cabaletta Bio director Scott C. Brun received a grant of stock options covering 22,000 shares of common stock. The options have an exercise price of $3.22 per share and expire on June 8, 2036. They vest in full on the earlier of June 9, 2027 or the date of the company’s next annual stockholder meeting. Following this award, Brun holds stock options for 22,000 shares. This is a compensation-related grant, not an open-market purchase or sale of shares.

Insider Trade Summary

Grant/Award: 22,000 shares

Grant/Award 1 txn

Insider Brun Scott C.

Role Director

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (Right to Buy)	22,000	$0.00	$0.00

Holdings After Transaction: Stock Option (Right to Buy) — 22,000 contracts (Direct)

Footnotes (1)

1. F1. This option shall vest in full upon the earlier of (i) June 9, 2027 or (ii) the date of the next annual meeting of the Corporation's stockholders.

Key Figures

Options granted: 22,000 options Exercise price: $3.22 per share Expiration date: June 8, 2036 +3 more

6 metrics

Options granted 22,000 options Stock Option (Right to Buy) grant to director

Exercise price $3.22 per share Conversion or exercise price of stock options

Expiration date June 8, 2036 Option term end

Vesting date trigger June 9, 2027 Earlier of this date or next annual meeting

Underlying shares 22,000 shares Common stock subject to the option

Post-grant option holdings 22,000 options Total options following transaction

Key Terms

Stock Option (Right to Buy), grant/award acquisition, expiration date, underlying security

4 terms

Stock Option (Right to Buy) financial

"security_title: Stock Option (Right to Buy)"

grant/award acquisition financial

"transaction_action: grant/award acquisition"

expiration date financial

"expiration_date: 2036-06-08T00:00:00.000Z"

The expiration date is the deadline after which a financial contract, such as an option or a futures agreement, is no longer valid or can be exercised. It matters to investors because it determines the timeframe during which they can take action or benefit from the contract, similar to how a coupon or a food item has a limited period of usefulness. Once the expiration date passes, the contract loses its value or ability to be used.

underlying security financial

"underlying_security_title: Common Stock"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did Cabaletta Bio (CABA) report in this Form 4 filing?

Cabaletta Bio reported a stock option grant to director Scott C. Brun. He received options for 22,000 shares of common stock as a compensation-related award, rather than buying or selling shares on the open market.

How many Cabaletta Bio (CABA) stock options were granted to Scott C. Brun?

Scott C. Brun was granted stock options for 22,000 shares of Cabaletta Bio common stock. These options give him the right to buy shares at a fixed exercise price if the options vest and he chooses to exercise them.

What is the exercise price of the Cabaletta Bio (CABA) options granted to Scott C. Brun?

The options granted to Scott C. Brun have an exercise price of $3.22 per share. This means he can purchase Cabaletta Bio common stock at $3.22 per share if the options vest and he exercises them before they expire.

When do Scott C. Brun’s Cabaletta Bio (CABA) stock options vest?

Scott C. Brun’s options vest in full on the earlier of June 9, 2027 or the date of Cabaletta Bio’s next annual stockholder meeting. Vested options can then be exercised to buy common shares at the set exercise price.

When do the Cabaletta Bio (CABA) stock options granted to Scott C. Brun expire?

The stock options granted to Scott C. Brun expire on June 8, 2036. If he does not exercise the options by that expiration date after they vest, his right to buy Cabaletta Bio shares under this grant will lapse.

Is this Cabaletta Bio (CABA) Form 4 an open-market purchase or sale?

No, this Form 4 reflects a compensation-related grant of stock options to director Scott C. Brun. It does not involve Cabaletta Bio shares being bought or sold on the open market, but rather an award of derivative securities.

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

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Accepted by SEC EDGAR 06/10/2026 - 06:51 PM 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).

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^*

Brun Scott C.

(Last) (First) (Middle)

C/O CABALETTA BIO, INC.

2929 ARCH STREET, SUITE 600

(Street)

PHILADELPHIA PENNSYLVANIA 19104

(City) (State) (Zip)

UNITED STATES

(Country)

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

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/09/2026

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

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

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

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)	$3.22	06/09/2026		A		22,000		(1)	06/08/2036	Common Stock	22,000	$0	22,000	D

Explanation of Responses:

1. This option shall vest in full upon the earlier of (i) June 9, 2027 or (ii) the date of the next annual meeting of the Corporation's stockholders.

	/s/ Michael Gerard, Attorney-in-Fact	06/10/2026
	** 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.
* Form 4: SEC 1474 (03-26)