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CSS LLC/IL — 13F Holdings & Portfolio

CIK 1103646 · latest 13F-HR filed 2026-08-14

Backtest portfolio

CSS LLC/IL manages $2.57B in 13F-reported U.S. long-equity assets across 1,001 reported positions as of its 2026-06-30 13F-HR filing. Its largest disclosed positions are LITE (9.56%), HPEPC (5.81%), ECHO (5.35%). Quarter over quarter (versus its 2026-03-31 filing) the fund opened 211 new positions, exited 184, added to 258, and trimmed 182.

AUM is the long-equity portion reported on Form 13F-HR. Excludes short positions, cash, foreign holdings, and non-13F assets. For informational purposes only — not investment advice.

Filer Information
Address
1 NORTH WACKER DRIVE
SUITE 3075
CHICAGO, IL 60606
Phone
(312) 542-8515
Filing Manager
CSS LLC/IL
CHICAGO, IL
Signatory
Mitchel Bialek
CCO
Loading holdings…
AUM

$2.57B

Long-equity book

Holdings

1,001

Distinct positions

Period

2026-06-30

Filed 2026-08-14

Q/Q Activity

+211 / −184 / ↑258 / ↓182

vs 2026-03-31

Firm Profile & Key People
Name Title / Status Ownership Type

Top Adds (vs prior quarter)

  • HEWLETT PACKARD ENTERPRISE C$141.9M +1902.6%
  • APOLLO GLOBAL MGMT INC$66.5M +408.4%
  • BANK OF AMER CORP$51.0M +413.5%
  • WOLFSPEED INC$40.7M +301.2%
  • LUMENTUM HLDGS INC$29.1M +13.4%
Show all 258 →

Top Trims

  • PEABODY ENGR CORP-$30.8M -81.5%
  • TRANSOCEAN INC-$26.0M -52.5%
  • NEXTERA ENERGY INC-$19.0M -69.7%
  • ALNYLAM PHARMACEUTICALS INC-$13.0M -54.3%
  • CHEESECAKE FACTORY INC-$9.6M -71.6%
Show all 182 →

New Positions

  • SUPER MICRO COMPUTER INC$45.3M
  • MICROCHIP TECHNOLOGY INC.$43.0M
  • BOEING CO$23.6M
  • IREN LIMITED$21.2M
  • DIGITALOCEAN HLDGS INC$19.5M
Show all 211 →

Exited Positions

  • JAZZ INVESTMENTS I LTD$63.9M
  • LIVE NATION ENTERTAINMENT IN$49.9M
  • STRIDE INC$17.8M
  • CSG SYS INTL INC$9.1M
  • HOLOGIC INC$8.9M
Show all 184 →
All Holdings

Rows tagged Call or Put are options positions, not stock. Per SEC Form 13F-HR, Value shows the notional value of the underlying (shares covered × underlying price), not the option premium. Shares is the number of underlying shares covered (divide by 100 for contract count).

# Issuer Symbol CUSIP Value Weight Shares Type
1 LUMENTUM HLDGS INC LITE 55024UAF6 $245.6M 9.56% 37,554,000 PRN
2 HEWLETT PACKARD ENTERPRISE C HPEPC 42824C208 $149.3M 5.81% 1,276,322 SH
3 ECHOSTAR CORP ECHO 278768AB2 $137.4M 5.35% 43,925,753 PRN
4 APOLLO GLOBAL MGMT INC APO 03769M304 $82.8M 3.22% 1,361,499 SH
5 BANK OF AMER CORP BACPL 060505682 $63.3M 2.46% 50,372 SH
6 WOLFSPEED INC WOLF 977852AP7 $54.2M 2.11% 13,773,940 PRN
7 SUPER MICRO COMPUTER INC SMCIP 86800U500 $45.3M 1.76% 878,227 SH
8 CORE SCIENTIFIC INC NEW CORZW 21874A114 $44.2M 1.72% 2,351,492 SH
9 MICROCHIP TECHNOLOGY INC. MCHPP 595017302 $43.0M 1.67% 558,552 SH
10 CLOUDFLARE INC NET 18915MAC1 $33.5M 1.31% 26,112,000 PRN
11 AKAMAI TECHNOLOGIES INC AKAM 00971TAN1 $29.6M 1.15% 24,797,000 PRN
12 GAMESTOP CORP Put GME 36467W109 $27.2M 1.06% 1,230,200 SH
13 ALBEMARLE CORP ALBPA 012653200 $26.1M 1.02% 470,583 SH
14 CENTERPOINT ENERGY INC CNP 15189TBD8 $25.3M 0.98% 21,000,000 PRN
15 EQUINOX GOLD CORP EQX 29446YAC0 $25.1M 0.98% 14,895,000 PRN
16 BOEING CO BAPA 097023204 $23.6M 0.92% 349,354 SH
17 TRANSOCEAN INC — 893830BW8 $23.5M 0.91% 15,168,000 PRN
18 EL PASO ENERGY CAP TR I EPPC 283678209 $22.6M 0.88% 446,461 SH
19 INVESCO EXCHANGE TRADED FD T RSP 46137V357 $22.1M 0.86% 104,072 SH
20 VANGUARD INDEX FDS VOO 922908363 $22.1M 0.86% 32,210 SH
21 KINDER MORGAN INC DEL Put KMI 49456B101 $21.7M 0.85% 678,900 SH
22 IREN LIMITED IREN 46270CAD1 $21.2M 0.83% 6,000,000 PRN
23 DIGITALOCEAN HLDGS INC DOCN 25402DAB8 $19.5M 0.76% 17,243,000 PRN
24 PTC THERAPEUTICS INC PTC 69366JAD3 $18.6M 0.73% 12,002,000 PRN
25 SNOWFLAKE INC SNOW 833445AD1 $16.5M 0.64% 9,300,000 PRN
26 XEROX HOLDINGS CORP Put — 98421M956 $16.0M 0.62% 5,100,000 SH
27 WESTERN DIGITAL CORP WDC 958102105 $15.9M 0.62% 24,933 SH
28 GAMESTOP CORP GME 36467WAG4 $15.2M 0.59% 14,944,000 PRN
29 ISHARES GOLD TR IAU 464285204 $15.1M 0.59% 200,040 SH
30 KIMCO REALTY CORP KIMPN 49446R687 $15.0M 0.58% 237,147 SH
31 STATE STR SPDR S&P 500 ETF T Call SPY 78462F103 $14.2M 0.55% 19,000 SH
32 ALPHABET INC GOOGN 02079K602 $13.4M 0.52% 266,589 SH
33 STATE STR SPDR S&P 500 ETF T SPY 78462F103 $12.9M 0.50% 17,269 SH
34 PENUMBRA INC PEN 70975L107 $12.2M 0.48% 38,740 SH
35 IONIS PHARMACEUTICALS INC IONS 462222100 $12.1M 0.47% 152,289 SH
36 BRIDGEBIO PHARMA INC BBIO 10806XAJ1 $12.1M 0.47% 7,175,000 PRN
37 CELCUITY INC CELC 15102KAA8 $11.9M 0.46% 5,310,000 PRN
38 HAEMONETICS CORP MASS HAE 405024AD2 $11.6M 0.45% 11,500,000 PRN
39 PENUMBRA INC Put PEN 70975L107 $11.4M 0.44% 36,100 SH
40 GUARDANT HEALTH INC GH 40131MAD1 $11.3M 0.44% 4,514,000 PRN
41 MARA HOLDINGS INC MARA 565788AD8 $11.1M 0.43% 10,000,000 PRN
42 BROOKDALE SR LIVING INC — 112463AC8 $11.0M 0.43% 5,632,000 PRN
43 ALNYLAM PHARMACEUTICALS INC ALNY 02043QAB3 $10.9M 0.42% 9,063,000 PRN
44 TRANSMEDICS GROUP INC TMDX 89377MAB5 $10.9M 0.42% 10,000,000 PRN
45 ON SEMICONDUCTOR CORP ON 682189AU9 $10.4M 0.40% 8,619,000 PRN
46 OCEANHAWK ACQUISITION CORP OHAC G6722R107 $10.3M 0.40% 1,038,610 SH
47 PPL CAP FDG INC PPL 69352PAS2 $10.2M 0.40% 8,988,000 PRN
48 FUTURECORP SPACE ACQUISITION FTRA.U G37307124 $10.1M 0.39% 1,000,000 SH
49 ELECTRONIC ARTS INC Put EA 285512109 $9.8M 0.38% 47,800 SH
50 MARA HOLDINGS INC MARA 565788AF3 $9.5M 0.37% 9,467,000 PRN
Filing History
Period Filed AUM Holdings Accession
2026-06-30 2026-08-14 $2.57B 1,001 0001103646-26-000012
2026-03-31 2026-05-15 $2.09B 961 0001103646-26-000009
2025-12-31 2026-02-17 $2.25B 999 0001103646-26-000003
2025-09-30 2025-11-13 $2.23B 985 0001103646-25-000009