Cabaletta Bio (CABA) CEO awarded 674,000-share stock option grant

Rhea-AI Filing Summary

Nichtberger Steven reported acquisition or exercise transactions in this Form 4 filing.

Cabaletta Bio reported that President and CEO Steven Nichtberger received a grant of stock options covering 674,000 shares of the company’s common stock. The options were awarded at no cost to him, increasing his directly held option position to 674,000 options after the grant.

According to the vesting terms, 25% of the shares underlying this option will vest and become exercisable on March 1, 2027. The remaining 75% will vest in twelve substantially equal quarterly installments after that date, conditioned on his continued service with the company on each vesting date.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Nichtberger Steven

Role President & CEO

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (Right to Buy)	674,000	$0.00	--

Holdings After Transaction: Stock Option (Right to Buy) — 674,000 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^*

Nichtberger Steven

(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)

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

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		674,000		(1)	03/01/2036	Common Stock	674,000	$0.00	674,000	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) disclose for Steven Nichtberger?

Cabaletta Bio disclosed that President and CEO Steven Nichtberger received a stock option grant for 674,000 shares. The award was granted at no cost to him and represents a new equity incentive tied to his continued service with the company over time.

How many stock options were granted to the Cabaletta Bio (CABA) CEO?

The CEO of Cabaletta Bio, Steven Nichtberger, was granted stock options covering 674,000 shares of common stock. This entire amount reflects a single award and results in total directly held options of 674,000 following the reported transaction on the Form 4.

What is the vesting schedule for Steven Nichtberger’s new Cabaletta Bio (CABA) options?

The CEO’s option grant vests 25% of the underlying shares on March 1, 2027. The remaining 75% vests in twelve substantially equal quarterly installments afterward, provided he continues serving the company on each vesting date, aligning incentives with long-term tenure.

Did Steven Nichtberger buy or sell Cabaletta Bio (CABA) shares in this Form 4?

This Form 4 reports an acquisition of stock options by grant, not an open-market buy or sale of shares. The transaction is coded as a grant or award, increasing his option holdings without reporting any stock disposition or cash purchase activity.

How does this Form 4 affect Steven Nichtberger’s Cabaletta Bio (CABA) holdings?

After the grant, Steven Nichtberger directly holds stock options for 674,000 shares of Cabaletta Bio common stock. These options vest over time starting in 2027, so the economic benefit depends on future vesting and any eventual exercise of the vested options.

Are there performance conditions on the new Cabaletta Bio (CABA) option grant?

The disclosed terms describe time-based vesting linked to continued service, not specific performance targets. Vesting occurs 25% on March 1, 2027, with the remainder in twelve substantially equal quarterly installments, assuming the CEO remains in service on each vesting date.