Mark Simon - 21 Jan 2026 Form 4 Insider Report for Cabaletta Bio, Inc. (CABA)

Reporting relationship: Director
Issuer ticker: CABA
Reported as of: 21 Jan 2026
Net transaction value: +$25,261
SEC form: 4
Accepted by SEC: 21 Jan 2026, 18:53:57 UTC
Prior SEC filing: 09 Jun 2025
Next SEC filing: 10 Jun 2026
Source filing: View source filing
Reporting owner signature: By: /s/ Michael Gerard, as Attorney-in-Fact

Key filing fact

Mark Simon filed Form 4 for Cabaletta Bio, Inc. (CABA) on 21 Jan 2026.

Key facts

This page summarizes Mark Simon's Form 4 filing for Cabaletta Bio, Inc. (CABA).
1 reported transaction and 0 derivative rows are listed below.
Accepted by SEC: 21 Jan 2026, 18:53.

Change

Previous filing in this sequence was filed on 09 Jun 2025.
Current net transaction value: +$25,261.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001400717 Primary reporting owner

Simon Mark

Relationship: Director
Address: C/O CABALETTA BIO, INC., 2929 ARCH STREET, SUITE 600, PHILADELPHIA
Signature: By: /s/ Michael Gerard, as Attorney-in-Fact
Signature date: 21 Jan 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

CABA transaction

Common Stock

Purchase

Transaction value: $25,261
Shares: +11,061
Change %: +8.1%
Price: $2.28
Shares after: 147,205
Date: 21 Jan 2026
Ownership: Direct
Footnotes: F1

CABA holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 7,000
Date: 21 Jan 2026
Ownership: By Spouse

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 1 footnote

Footnote F1

The price reported in Column 4 is a weighted average price. These shares were purchased at prices ranging from $2.245 to $2.32, inclusive. The reporting person has provided to the Issuer, and undertakes to provide any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.