Cabaletta Bio, Inc.
US ˙ NasdaqGS ˙ US12674W1099

SecurityCABA / Cabaletta Bio, Inc.
InstitutionCitadel Advisors Llc
ManagerKen Griffin
Latest Disclosed Ownership3,150,275 shares
Ownership 3.40%
Citadel Advisors Llc ownership in CABA / Cabaletta Bio, Inc.

2025-11-14 - Citadel Advisors Llc has filed an SCHEDULE 13G/A form with the Securities and Exchange Commission (SEC) disclosing ownership of 3,150,275 shares of Cabaletta Bio, Inc. (US:CABA). This represents 3.4 percent ownership of the company. In their previous filing dated 2025-06-20 , Citadel Advisors Llc had reported owning 4,818,560 shares, indicating a decrease of -34.62 percent.

Citadel Advisors Llc has a history of taking positions in derivatives of the underlying security (CABA) in the form of stock options. The firm currently holds call options representing 478,600 of underlying shares valued at $1,287,434 USD and put options representing 82,200 of underlying shares valued at $221,118 USD .

Note: prior versions of this page mistakenly stated that the share values represented the number of options, not the number of underlying shares. For more information on the data backing these reports, please see the SEC document Frequently Asked Questions About Form 13F.

Institutional Ownership: 13D/G Filings

This table shows a history of the 13D/G filings made by the investor and/or investor group. Note that the share values in this table are not directly comparable to any numbers shown in the 13F table (if any).

File
Date
Effective
Date
Form Prev
Shares
Latest
Shares
ΔShares
(Percent)
Ownership
(Percent)
ΔOwnership
(Percent)
2025-11-14 2025-11-14 13G/A 4,818,560 3,150,275 -34.62 3.40 -34.62
2025-06-20 2025-06-20 13G 4,818,560 5.20 1,633.33
2023-02-14 2023-02-14 13G/A 0.30 -94.44
2022-02-14 2022-02-14 13G/A 5.40 -3.57
2021-11-01 2021-11-01 13G 5.60

Important Note: One of the primary uses of the 13D/G filings is to evaluate the ability of a firm to control a company (ie, the "beneficial ownership"). To that end, firms are required to report not just direct holdings in companies, but indirect holdings that they control. For investment firms, these indirect holdings can include shares in funds they manage, advisory accounts, and in the case of activist campaigns, pledged votes. Therefore, share counts listed in 13D/G filings can differ significantly than share counts listed in 13F filings.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

CABA / Cabaletta Bio, Inc. Historical Put/Call Ratio
Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date
Effective
Date
Form Security Class ID Avg Price
Paid (Est)
Reported
Shares
ΔShares ΔShares
(%)
Reported
Value
(x1000)
ΔValue
(%)
Alloc
(%)
ΔAlloc ΔAlloc (%) Cost Basis
(x1000)
Unrealized
Gain/Loss
(x1000)
2026-05-15 2026-03-31 13F CABALETTA BIO COM 12674W109 0 -33,502 -100.00 0 -100.00
2026-02-17 2025-12-31 13F CABALETTA BIO COM 12674W109 33,502 -671,963 -95.25 73 -95.58 0.0000
2025-11-14 2025-09-30 13F CABALETTA BIO COM 12674W109 705,465 -982,515 -58.21 1,651 -35.67 0.0003
2025-08-14 2025-06-30 13F CABALETTA BIO COM 12674W109 1,687,980 1,687,630 482,180.00 2,566 0.0004
2025-05-15 2025-03-31 13F CABALETTA BIO COM 12674W109 350 350 0 0.0000
2025-02-14 2024-12-31 13F CABALETTA BIO COM 12674W109 0 -4,511 -100.00 0 -100.00
2024-11-14 2024-09-30 13F CABALETTA BIO COM 12674W109 4,511 -315,035 -98.59 21 -99.12 0.0000
2024-08-14 2024-06-30 13F CABALETTA BIO COM 12674W109 319,546 317,305 14,159.08 2,390 6,189.47 0.0005
2024-05-15 2024-03-31 13F CABALETTA BIO COM 12674W109 2,241 -31,639 -93.39 38 -95.06 0.0000
2024-02-14 2023-12-31 13F CABALETTA BIO COM 12674W109 33,880 31,417 1,275.56 769 1,978.38 0.0002
2023-11-14 2023-09-30 13F CABALETTA BIO COM 12674W109 2,463 2,463 37 0.0000
2023-08-14 2023-06-30 13F CABALETTA BIO COM 12674W109 0 -21,197 -100.00 0 -100.00
2023-05-15 2023-03-31 13F CABALETTA BIO COM 12674W109 21,197 -51,981 -71.03 175 -74.11 0.0000
2023-02-14 2022-12-31 13F CABALETTA BIO COM 12674W109 73,178 73,178 677 0.0002
2022-11-14 2022-09-30 13F CABALETTA BIO COM 12674W109 0 -1,254,479 -100.00 0 -100.00
2022-08-15 2022-06-30 13F CABALETTA BIO COM 12674W109 1,254,479 -220,621 -14.96 1,330 -55.58 0.0003
2022-05-16 2022-03-31 13F CABALETTA BIO COM 12674W109 1,475,100 -24,523 -1.64 2,994 -47.32 0.0006
2022-02-14 2021-12-31 13F CABALETTA BIO COM 12674W109 1,499,623 940,156 168.04 5,683 -16.46 0.0012
2021-11-15 2021-09-30 13F CABALETTA BIO Cmn 12674W109 559,467 522,135 1,398.63 6,803 2,019.31 0.0014
2021-08-16 2021-06-30 13F CABALETTA BIO COM 12674W109 37,332 18,481 98.04 321 53.59 0.0001
2021-05-21 2021-03-31 13F/A-1 CABALETTA BIO COM 12674W109 18,851 8,042 74.40 209 54.81 0.0001
2021-05-17 2021-03-31 13F CABALETTA BIO COM 12674W109 18,851 8,042 209 0.0001
2021-02-16 2020-12-31 13F CABALETTA BIO COM 12674W109 10,809 10,809 -42.66 135 -35.41 0.0000
2020-08-14 2020-06-30 13F CABALETTA BIO Cmn 12674W109 0 -16,312 -100.00 0 -100.00
2020-05-15 2020-03-31 13F CABALETTA BIO Cmn 12674W109 16,312 16,312 119 0.0001
Disclosed Call Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share
Price
Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-15 2026-03-31 13F CABALETTA BIO COM Call 478,600 115.00 1,287 164.27 n/a n/a n/a
2026-02-17 2025-12-31 13F CABALETTA BIO COM Call 222,600 -9.07 487 -14.86 n/a n/a n/a
2025-11-14 2025-09-30 13F CABALETTA BIO COM Call 244,800 220.00 573 393.10 n/a n/a n/a
2025-08-14 2025-06-30 13F CABALETTA BIO COM Call 76,500 88.89 116 107.14 n/a n/a n/a
2025-05-15 2025-03-31 13F CABALETTA BIO COM Call 40,500 -70.31 56 -81.88 n/a n/a n/a
2025-02-14 2024-12-31 13F CABALETTA BIO COM Call 136,400 840.69 310 354.41 n/a n/a n/a
2024-11-14 2024-09-30 13F CABALETTA BIO COM Call 14,500 -23.28 68 -51.77 n/a n/a n/a
2024-08-14 2024-06-30 13F CABALETTA BIO COM Call 18,900 -74.46 141 -88.83 n/a n/a n/a
2024-05-15 2024-03-31 13F CABALETTA BIO COM Call 74,000 35.04 1,262 1.53 n/a n/a n/a
2024-02-14 2023-12-31 13F CABALETTA BIO COM Call 54,800 495.65 1,244 787.86 n/a n/a n/a
2023-11-14 2023-09-30 13F CABALETTA BIO COM Call 9,200 -25.20 140 -11.39 n/a n/a n/a
2023-08-14 2023-06-30 13F CABALETTA BIO COM Call 12,300 -42.79 159 -10.73 n/a n/a n/a
2023-05-15 2023-03-31 13F CABALETTA BIO COM Call 21,500 -11.16 178 -20.63 n/a n/a n/a
2023-02-14 2022-12-31 13F CABALETTA BIO COM Call 24,200 -70.91 224 312.96 n/a n/a n/a
2022-11-14 2022-09-30 13F CABALETTA BIO COM Call 83,200 54 n/a n/a n/a
2022-05-16 2022-03-31 13F CABALETTA BIO COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2022-02-14 2021-12-31 13F CABALETTA BIO COM Call 19,800 -64.96 75 -89.08 n/a n/a n/a
2021-11-15 2021-09-30 13F CABALETTA BIO Cmn Call 56,500 315.44 687 487.18 n/a n/a n/a
2021-08-16 2021-06-30 13F CABALETTA BIO COM Call 13,600 117 n/a n/a n/a
Disclosed Put Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share Price Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-15 2026-03-31 13F CABALETTA BIO COM Put 82,200 221 n/a n/a n/a
2025-11-14 2025-09-30 13F CABALETTA BIO COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2025-08-14 2025-06-30 13F CABALETTA BIO COM Put 28,800 -78.56 44 -76.88 n/a n/a n/a
2025-05-15 2025-03-31 13F CABALETTA BIO COM Put 134,300 97.50 186 20.78 n/a n/a n/a
2025-02-14 2024-12-31 13F CABALETTA BIO COM Put 68,000 79.42 154 -13.48 n/a n/a n/a
2024-11-14 2024-09-30 13F CABALETTA BIO COM Put 37,900 70.72 179 7.23 n/a n/a n/a
2024-08-14 2024-06-30 13F CABALETTA BIO COM Put 22,200 30.59 166 -42.76 n/a n/a n/a
2024-05-15 2024-03-31 13F CABALETTA BIO COM Put 17,000 139.44 290 80.12 n/a n/a n/a
2024-02-14 2023-12-31 13F CABALETTA BIO COM Put 7,100 -23.66 161 14.18 n/a n/a n/a
2023-11-14 2023-09-30 13F CABALETTA BIO COM Put 9,300 20.78 142 42.42 n/a n/a n/a
2023-08-14 2023-06-30 13F CABALETTA BIO COM Put 7,700 -35.83 99 0.00 n/a n/a n/a
2023-05-15 2023-03-31 13F CABALETTA BIO COM Put 12,000 -31.82 99 -38.89 n/a n/a n/a
2023-02-14 2022-12-31 13F CABALETTA BIO COM Put 17,600 -1.68 163 1,250.00 n/a n/a n/a
2022-11-14 2022-09-30 13F CABALETTA BIO COM Put 17,900 12 n/a n/a n/a
2022-05-16 2022-03-31 13F CABALETTA BIO COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2022-02-14 2021-12-31 13F CABALETTA BIO COM Put 44,100 167 n/a n/a n/a
2022-03-11 2021-09-30 13F/A CABALETTA BIO COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2021-11-15 2021-09-30 13F CABALETTA BIO COM Put 0 0 n/a n/a n/a
2021-08-16 2021-06-30 13F CABALETTA BIO COM Put 15,100 130 n/a n/a n/a
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.