Mark Simon Form 3 Cabaletta Bio / Mark Simon ownership change

SEC Form 3

FORM 3

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

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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

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1. Name and Address of Reporting Person^*

Simon Mark

(Last) (First) (Middle)

C/O CABALETTA BIO, INC.

2929 ARCH STREET, SUITE 600

(Street)

PHILADELPHIA PA 19104

(City) (State) (Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
10/24/2019

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

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

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

5. 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 Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series A-1 Preferred Stock	(1)	(1)	Common Stock	18,144	(1)	D
Stock Option (Right to Buy)	(1)(2)	10/28/2028	Common Stock	27,968	1.01	D
Stock Option (Right to Buy)	(1)(3)	02/18/2029	Common Stock	18,460	6.3	D

Explanation of Responses:

1. The Series A-1 Preferred Stock is convertible into shares of the Issuer's Common Stock on a one-for-1.5 basis. Upon the closing of the Issuer's initial public offering, all shares of Series A-1 Preferred Stock will convert into shares of Common Stock of the Issuer. The Series A-1 Preferred Stock has no expiration date.

2. This option vests in eight equal quarterly installments beginning on October 11, 2018.

3. This option vests in eight equal quarterly installments beginning on February 19, 2019.

Remarks:

Exhibit 24 - Power of Attorney

	/s/ Mark Simon	10/24/2019
	** 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 5 (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.
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