CABA

SEC source: 0000950170-25-074826 · ownership.xml · derivative · entry 9

Nichtberger Steven · CIK 0001487989 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 411,600 shares

Expires 2033-01-17

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. The transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act of 1934, as amended, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074826 · ownership.xml · derivative · entry 8

Nichtberger Steven · CIK 0001487989 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 380,000

Underlying: Common Stock · 380,000 shares

Expires 2032-01-17

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the option holder must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. The transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act of 1934, as amended, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074826 · ownership.xml · derivative · entry 7

Nichtberger Steven · CIK 0001487989 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 380,000 shares

Expires 2032-01-17

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. The transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act of 1934, as amended, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074826 · ownership.xml · derivative · entry 6

Nichtberger Steven · CIK 0001487989 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 333,500

Underlying: Common Stock · 333,500 shares

Expires 2031-02-28

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the option holder must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. The transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act of 1934, as amended, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074826 · ownership.xml · derivative · entry 5

Nichtberger Steven · CIK 0001487989 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 333,500 shares

Expires 2031-02-28

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. The transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act of 1934, as amended, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074826 · ownership.xml · derivative · entry 4

Nichtberger Steven · CIK 0001487989 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 300,000

Underlying: Common Stock · 300,000 shares

Expires 2030-02-28

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the option holder must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. The transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act of 1934, as amended, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074826 · ownership.xml · derivative · entry 3

Nichtberger Steven · CIK 0001487989 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 300,000 shares

Expires 2030-02-28

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. The transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act of 1934, as amended, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074826 · ownership.xml · derivative · entry 2

Nichtberger Steven · CIK 0001487989 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 99,714

Underlying: Common Stock · 99,714 shares

Expires 2029-10-23

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the option holder must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. The transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act of 1934, as amended, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074826 · ownership.xml · derivative · entry 1

Nichtberger Steven · CIK 0001487989 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 99,714 shares

Expires 2029-10-23

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. The transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act of 1934, as amended, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074823 · ownership.xml · derivative · entry 4

Tomasello Shawn · CIK 0001617239 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 22,000

Underlying: Common Stock · 22,000 shares

Expires 2034-06-02

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074823 · ownership.xml · derivative · entry 3

Tomasello Shawn · CIK 0001617239 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 22,000 shares

Expires 2034-06-02

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074823 · ownership.xml · derivative · entry 2

Tomasello Shawn · CIK 0001617239 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 44,000

Underlying: Common Stock · 44,000 shares

Expires 2033-07-20

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074823 · ownership.xml · derivative · entry 1

Tomasello Shawn · CIK 0001617239 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 44,000 shares

Expires 2033-07-20

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074818 · ownership.xml · derivative · entry 14

Marda Anup · CIK 0001790410 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 130,000

Underlying: Common Stock · 130,000 shares

Expires 2034-02-28

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074818 · ownership.xml · derivative · entry 13

Marda Anup · CIK 0001790410 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 130,000 shares

Expires 2034-02-28

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074818 · ownership.xml · derivative · entry 12

Marda Anup · CIK 0001790410 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 150,000

Underlying: Common Stock · 150,000 shares

Expires 2033-01-17

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074818 · ownership.xml · derivative · entry 11

Marda Anup · CIK 0001790410 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 150,000 shares

Expires 2033-01-17

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074818 · ownership.xml · derivative · entry 10

Marda Anup · CIK 0001790410 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 135,000

Underlying: Common Stock · 135,000 shares

Expires 2032-01-17

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074818 · ownership.xml · derivative · entry 9

Marda Anup · CIK 0001790410 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 135,000 shares

Expires 2032-01-17

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074818 · ownership.xml · derivative · entry 8

Marda Anup · CIK 0001790410 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 100,000

Underlying: Common Stock · 100,000 shares

Expires 2031-02-28

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074818 · ownership.xml · derivative · entry 7

Marda Anup · CIK 0001790410 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 100,000 shares

Expires 2031-02-28

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074818 · ownership.xml · derivative · entry 6

Marda Anup · CIK 0001790410 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 24,711

Underlying: Common Stock · 24,711 shares

Expires 2030-02-28

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074818 · ownership.xml · derivative · entry 5

Marda Anup · CIK 0001790410 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 24,711 shares

Expires 2030-02-28

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074818 · ownership.xml · derivative · entry 4

Marda Anup · CIK 0001790410 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 66,463

Underlying: Common Stock · 66,463 shares

Expires 2029-10-23

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074818 · ownership.xml · derivative · entry 3

Marda Anup · CIK 0001790410 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 66,463 shares

Expires 2029-10-23

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074818 · ownership.xml · derivative · entry 2

Marda Anup · CIK 0001790410 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 139,282

Underlying: Common Stock · 139,282 shares

Expires 2029-01-23

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074818 · ownership.xml · derivative · entry 1

Marda Anup · CIK 0001790410 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 139,282 shares

Expires 2029-01-23

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074817 · ownership.xml · derivative · entry 8

Simon Mark · CIK 0001400717 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 22,000

Underlying: Common Stock · 22,000 shares

Expires 2034-06-02

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074817 · ownership.xml · derivative · entry 7

Simon Mark · CIK 0001400717 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 22,000 shares

Expires 2034-06-02

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074817 · ownership.xml · derivative · entry 6

Simon Mark · CIK 0001400717 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 22,000

Underlying: Common Stock · 22,000 shares

Expires 2033-05-31

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074817 · ownership.xml · derivative · entry 5

Simon Mark · CIK 0001400717 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 22,000 shares

Expires 2033-05-31

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074817 · ownership.xml · derivative · entry 4

Simon Mark · CIK 0001400717 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 22,000

Underlying: Common Stock · 22,000 shares

Expires 2031-05-31

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074817 · ownership.xml · derivative · entry 3

Simon Mark · CIK 0001400717 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 22,000 shares

Expires 2031-05-31

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074817 · ownership.xml · derivative · entry 2

Simon Mark · CIK 0001400717 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 18,460

Underlying: Common Stock · 18,460 shares

Expires 2029-02-18

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074817 · ownership.xml · derivative · entry 1

Simon Mark · CIK 0001400717 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 18,460 shares

Expires 2029-02-18

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074816 · ownership.xml · derivative · entry 12

Binder Gwendolyn · CIK 0001791742 · President, Science & Tech.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 130,000

Underlying: Common Stock · 130,000 shares

Expires 2034-02-28

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074816 · ownership.xml · derivative · entry 11

Binder Gwendolyn · CIK 0001791742 · President, Science & Tech.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 130,000 shares

Expires 2034-02-28

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074816 · ownership.xml · derivative · entry 10

Binder Gwendolyn · CIK 0001791742 · President, Science & Tech.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 176,000

Underlying: Common Stock · 176,000 shares

Expires 2033-01-17

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074816 · ownership.xml · derivative · entry 9

Binder Gwendolyn · CIK 0001791742 · President, Science & Tech.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 176,000 shares

Expires 2033-01-17

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074816 · ownership.xml · derivative · entry 8

Binder Gwendolyn · CIK 0001791742 · President, Science & Tech.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 160,000

Underlying: Common Stock · 160,000 shares

Expires 2032-01-17

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074816 · ownership.xml · derivative · entry 7

Binder Gwendolyn · CIK 0001791742 · President, Science & Tech.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 160,000 shares

Expires 2032-01-17

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074816 · ownership.xml · derivative · entry 6

Binder Gwendolyn · CIK 0001791742 · President, Science & Tech.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 125,000

Underlying: Common Stock · 125,000 shares

Expires 2031-02-28

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074816 · ownership.xml · derivative · entry 5

Binder Gwendolyn · CIK 0001791742 · President, Science & Tech.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 125,000 shares

Expires 2031-02-28

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074816 · ownership.xml · derivative · entry 4

Binder Gwendolyn · CIK 0001791742 · President, Science & Tech.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 29,908

Underlying: Common Stock · 29,908 shares

Expires 2029-10-23

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074816 · ownership.xml · derivative · entry 3

Binder Gwendolyn · CIK 0001791742 · President, Science & Tech.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 29,908 shares

Expires 2029-10-23

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074816 · ownership.xml · derivative · entry 2

Binder Gwendolyn · CIK 0001791742 · President, Science & Tech.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 66,667

Underlying: Common Stock · 66,667 shares

Expires 2029-08-21

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074816 · ownership.xml · derivative · entry 1

Binder Gwendolyn · CIK 0001791742 · President, Science & Tech.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 66,667 shares

Expires 2029-08-21

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074811 · ownership.xml · derivative · entry 10

Das Arun · CIK 0001903997 · Chief Business Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 100,000

Underlying: Common Stock · 100,000 shares

Expires 2034-02-28

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074811 · ownership.xml · derivative · entry 9

Das Arun · CIK 0001903997 · Chief Business Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 100,000 shares

Expires 2034-02-28

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-074811 · ownership.xml · derivative · entry 8

Das Arun · CIK 0001903997 · Chief Business Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 150,000

Underlying: Common Stock · 150,000 shares

Expires 2033-01-17

F3 · derivative.exercise_price: The exercise price of the option is $1.92 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date. Under the terms of the stock option award repricing, a repriced stock option award will revert to its original exercise price if exercised during the Retention Period. The "Retention Period", through which the Reporting Person must remain in service to the Issuer, commenced on the Repricing Date and ends upon the earliest of (i) the one-year anniversary of the Repricing Date, (ii) a Sale Event (as defined in the 2018 Plan and 2019 Plan, as applicable) and (iii) the termination of the Reporting Person's Service Relationship (as defined in the 2018 Plan and 2019 Plan, as applicable) due to the Reporting Person's death or disability.

F1 · kind: On May 15, 2025, the Issuer's board of directors approved an option repricing (the "Repricing"), to be effective May 19, 2025 (the "Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Incentive Plan, as amended (the "2018 Plan") or the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan, as amended (the "2019 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.