CSS LLC IL
Q2 2025 Form 13-F
CHICAGO, ILLINOIS
CIK 0001103646
· Institutional investment manager
$2.1B Reported Value Total
Reported value
$2.1B
Quarter over quarter
+6.8%
Holdings
590
Top-10 concentration
24.3%
Key People
Named on the latest Form 13-F filing — not necessarily an owner
Mitchel Bialek
CCO
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Q2 2025 13F record
Q2 2025 13F filing summary
| Period of report | June 30, 2025 |
|---|---|
| Filed | August 14, 2025 |
| Form | 13F-HR |
| Reported value | $2.1B |
| Positions | 590 |
| Change in reported value | +17.7% |
| New positions | 204 |
| Exited positions | 161 |
| Position turnover | 48.6% |
| Top-10 concentration | 24.3% |
13F filings by quarter
| Quarter | Positions | Value |
|---|---|---|
|
Q2 2026 13F
Filed Aug 14, 2026
|
694 | $2.6B |
|
Q1 2026 13F
Filed May 15, 2026
|
652 | $2.1B |
|
Q4 2025 13F
Filed Feb 17, 2026
|
649 | $2.2B |
|
Q3 2025 13F
Filed Nov 13, 2025
|
604 | $2.2B |
|
Q2 2025 13F
Filed Aug 14, 2025
|
590 | $2.1B |
|
Q1 2025 13F
Filed May 15, 2025
|
550 | $1.8B |
|
Q4 2024 13F
Filed Feb 18, 2025
|
541 | $2.3B |
|
Q3 2024 13F
Filed Nov 14, 2024
|
496 | $2.2B |
|
Q2 2024 13F
Filed Aug 14, 2024
|
490 | $2.0B |
|
Q1 2024 13F
Filed May 15, 2024
|
483 | $1.7B |
|
Q4 2023 13F
Filed Feb 14, 2024
|
447 | $1.7B |
|
Q3 2023 13F
Filed Nov 14, 2023
|
488 | $1.5B |
|
Q2 2023 13F
Filed Aug 14, 2023
|
526 | $1.6B |
|
Q1 2023 13F
Filed May 15, 2023
|
489 | $1.5B |
|
Q4 2022 13F
Filed Feb 14, 2023
|
617 | $1.8B |
|
Q3 2022 13F
Filed Nov 14, 2022
|
666 | $2.1B |
|
Q2 2022 13F
Filed Aug 15, 2022
|
732 | $2.5B |
|
Q1 2022 13F
Filed May 16, 2022
|
805 | $2.8B |
|
Q4 2021 13F
Filed Feb 14, 2022
|
900 | $2.8B |
|
Q3 2021 13F
Filed Nov 15, 2021
|
853 | $2.4B |
31 earlier quarters on file — choose one from the quarter menu above.
Top 20 holdings · Q2 2025
| # | Holding | Reported value | % of portfolio |
|---|---|---|---|
| 1 | MSTR P MICROSTRATEGY INC | $110.6M | 5.16% |
| 2 | LRN 1.125 09/01/27 STRIDE INC | $75.9M | 3.54% |
| 3 | IONS 0 04/01/26 IONIS PHARMACEUTICALS INC | $58.0M | 2.71% |
| 4 | JAZZ 2 06/15/26 JAZZ INVESTMENTS I LTD | $52.6M | 2.45% |
| 5 | SPY C SPDR S&P 500 ETF TR | $45.7M | 2.13% |
| 6 | FOUR 0 12/15/25 SHIFT4 PMTS INC | $43.5M | 2.03% |
| 7 | GME P GAMESTOP CORP NEW | $35.1M | 1.64% |
| 8 | STX 3.5 06/01/28 SEAGATE HDD CAYMAN | $35.0M | 1.63% |
| 9 | BTSGU BRIGHTSPRING HEALTH SVCS INC | $33.0M | 1.54% |
| 10 | VAC 0 01/15/26 MARRIOTT VACATIONS WORLDWIDE | $32.3M | 1.51% |
| 11 | MSTR 2.25 06/15/32 MICROSTRATEGY INC | $32.0M | 1.49% |
| 12 | NEEPRR NEXTERA ENERGY INC | $30.3M | 1.41% |
| 13 | SPY P SPDR S&P 500 ETF TR | $29.7M | 1.38% |
| 14 | IMAX 0.5 04/01/26 IMAX CORP | $25.5M | 1.19% |
| 15 | SNAP 0.75 08/01/26 SNAP INC | $23.2M | 1.08% |
| 16 | UBER 0.875 12/01/28 2028 UBER TECHNOLOGIES INC | $22.9M | 1.07% |
| 17 | BACPRL BANK AMERICA CORP | $22.9M | 1.07% |
| 18 | RIG 4.625 09/30/29 * TRANSOCEAN INC | $22.7M | 1.06% |
| 19 | BTU 3.25 03/01/28 PEABODY ENGR CORP | $21.7M | 1.01% |
| 20 | TVTX 2.5 09/15/25 TRAVERE THERAPEUTICS INC | $20.9M | 0.97% |
Values as reported on the Q2 2025 Form 13F. Every position is in the holdings table below.