SCHEDULE 13G

Cabaletta Bio Inc

Common stock, par value $0.00001 per share (the "Shares") · CUSIP: 12674W109

Event date: 2025-06-12

Reporting persons may disclose overlapping interests. Their amounts are shown individually and are not added into a filing total.

Filing-level shares

Unavailable

Percent of class

Unavailable

• Citadel Advisors LLC

  Shares: 4,687,280.00 · Class: 5.0%

• Citadel Advisors Holdings LP

  Shares: 4,687,280.00 · Class: 5.0%

• Citadel GP LLC

  Shares: 4,687,280.00 · Class: 5.0%

• Citadel Securities LLC

  Shares: 131,280.00 · Class: 0.1%

• Citadel Securities Group LP

  Shares: 131,280.00 · Class: 0.1%

• Citadel Securities GP LLC

  Shares: 131,280.00 · Class: 0.1%

• Kenneth Griffin

  Shares: 4,818,560.00 · Class: 5.2%

Amounts are as disclosed in this filing. Schedule type alone does not establish investment intent.