EXHIBIT 99.1

JOINT FILING AGREEMENT

The undersigned hereby agree that the Statement on Schedule 13G filed herewith (and any amendments thereto), relating to the Common Stock of Cabaletta Bio, Inc., a Delaware corporation, is being filed jointly with the Securities and Exchange Commission pursuant to Rule 13d-1(c) under the Securities Exchange Act of 1934, as amended, on behalf of each of the undersigned.

This Agreement may be executed in counterparts and each of such counterparts taken together shall constitute one and the same instrument.

Dated this 1^st day of November, 2021.

CITADEL SECURITIES LLC		CITADEL ADVISORS LLC
By:	/s/ Guy Miller	By:	/s/ Gregory Johnson
	Guy Miller, Authorized Signatory		Gregory Johnson, Authorized Signatory


CITADEL SECURITIES GROUP LP		CITADEL ADVISORS HOLDINGS LP
By:	/s/ Guy Miller	By:	/s/ Gregory Johnson
	Guy Miller, Authorized Signatory		Gregory Johnson, Authorized Signatory


CITADEL SECURITIES GP LLC		CITADEL GP LLC
By:	/s/ Guy Miller	By:	/s/ Gregory Johnson
	Guy Miller, Authorized Signatory		Gregory Johnson, Authorized Signatory


		KENNETH GRIFFIN
		By:	/s/ Gregory Johnson
			Gregory Johnson, attorney-in-fact*

Gregory Johnson is signing on behalf of Kenneth Griffin as attorney-in-fact pursuant to a power of attorney previously filed with the Securities and Exchange Commission, and hereby incorporated by reference herein. The power of attorney was filed as an attachment to a filing by Citadel Advisors LLC on Schedule 13G for Jaws Acquisitions Corp. on February 1, 2021.