Simplex Trading Portfolio holdings
Simplex Trading, founded in 2004 and headquartered in Chicago, Illinois, is a technology-driven proprietary trading firm specializing in market-making and liquidity provision, primarily in U.S. equity options and futures options. Leveraging advanced proprietary software and data-driven analysis, the firm optimizes trading strategies and develops innovative solutions to capitalize on financial market opportunities, maintaining a competitive edge through automation and a collaborative team of technologists and traders. With a workforce exceeding 300 and led by CEO Erik Swanson since 2014, Simplex operates with a low-ego, high-intelligence culture, focusing on minimal bureaucracy and rapid execution, while also making strategic venture capital investments in fintech startups. Recognized as a top workplace in Chicago by Built In’s 2025 awards, Simplex continues to evolve, blending cutting-edge technology with a commitment to market efficiency and growth.
Top Buys
| Rank | Stock | Value |
|---|---|---|
| 1 |
Netflix
NFLX
|
+$73.1M |
| 2 |
Western Digital
WDC
|
+$51.8M |
| 3 |
iShares Semiconductor ETF
SOXX
|
+$46M |
| 4 |
Meta Platforms (Facebook)
META
|
+$41.8M |
| 5 |
Alibaba
BABA
|
+$37.1M |
Top Sells
| Rank | Stock | Value |
|---|---|---|
| 1 |
NVIDIA
NVDA
|
+$262M |
| 2 |
Microsoft
MSFT
|
+$194M |
| 3 |
iShares Russell 2000 ETF
IWM
|
+$149M |
| 4 |
Apple
AAPL
|
+$119M |
| 5 |
Amazon
AMZN
|
+$107M |
Sector Composition
| Rank | Sector | Weight |
|---|---|---|
| 1 | Technology | 0.59% |
| 2 | Consumer Discretionary | 0.21% |
| 3 | Healthcare | 0.2% |
| 4 | Industrials | 0.18% |
| 5 | Communication Services | 0.16% |
| Name | Market Value | Portfolio Weight | Shares or Principal |
Change in Stake | Capital Flow | |
|---|---|---|---|---|---|---|
7076
PUT
California Water Service
CWT
$3.1B
| $8.67K | ﹤0.01% |
+200
| New | +$9.12K |
|
7077
CALL
Astec Industries
ASTE
$1.17B
| $8.66K | ﹤0.01% |
200
| – | – |
|
7078
CALL
Workiva
WK
$3.45B
| $8.63K | ﹤0.01% |
100
-17,900
| -99% | -$1.58M |
|
7079
Vanguard Long-Term Bond ETF
BLV
$5.74B
| $8.62K | ﹤0.01% |
+124
| New | +$8.78K |
|
7080
CALL
Flotek Industries
FTK
$789M
| $8.62K | ﹤0.01% |
500
-6,400
| -93% | -$102K |
|
7081
PUT
Ituran Location and Control
ITRN
$1.08B
| $8.6K | ﹤0.01% |
200
-1,100
| -85% | -$43.1K |
|
|
DKUP
7082
DELISTED
T-REX 2X Long DKNG Daily Target ETF
DKUP
| $8.58K | ﹤0.01% |
+700
| New | +$8.15K |
|
7083
YieldMax NFLX Option Income Strategy ETF
NFLY
$39.8M
| $8.57K | ﹤0.01% |
+714
| New | +$10.1K |
|
7084
CALL
PDF Solutions
PDFS
$1.72B
| $8.56K | ﹤0.01% |
300
-8,300
| -97% | -$230K |
|
7085
MGE Energy Inc
MGEE
$3.03B
| $8.55K | ﹤0.01% |
+109
| New | +$8.96K |
|
7086
Amtech Systems
ASYS
$239M
| $8.55K | ﹤0.01% |
+681
| New | +$6.13K |
|
7087
CALL
Kennametal
KMT
$2.56B
| $8.52K | ﹤0.01% |
300
-8,000
| -96% | -$204K |
|
7088
PUT
Flywire
FLYW
$2.04B
| $8.5K | ﹤0.01% |
600
-69,600
| -99% | -$953K |
|
|
NSLR
7089
PUT
Neostellar Capital Corp
NSLR
$258M
| $8.5K | ﹤0.01% |
900
-3,100
| -78% | -$29.2K |
|
|
PBT
7090
CALL
Permian Basin Royalty Trust
PBT
$1.36B
| $8.49K | ﹤0.01% |
500
-19,200
| -97% | -$344K |
|
7091
CALL
Codexis
CDXS
$158M
| $8.48K | ﹤0.01% |
5,200
-12,200
| -70% | -$24.9K |
|
7092
CALL
Carriage Services
CSV
$647M
| $8.46K | ﹤0.01% |
+200
| New | +$8.68K |
|
7093
PUT
Geospace Technologies
GEOS
$84M
| $8.46K | ﹤0.01% |
500
-42,900
| -99% | -$862K |
|
7094
OFG Bancorp
OFG
$2.21B
| $8.44K | ﹤0.01% |
206
-190
| -48% | -$7.78K |
|
7095
PUT
Anixa Biosciences
ANIX
$118M
| $8.42K | ﹤0.01% |
2,700
| – | – |
|
7096
CALL
HNI Corp
HNI
$3.08B
| $8.41K | ﹤0.01% |
+200
| New | +$8.45K |
|
7097
Allogene Therapeutics
ALLO
$625M
| $8.4K | ﹤0.01% |
6,133
+1,952
| +47% | +$2.58K |
|
7098
CALL
Evolent Health
EVH
$371M
| $8.4K | ﹤0.01% |
2,100
-200
| -9% | -$1.11K |
|
7099
PUT
908 Devices
MASS
$312M
| $8.4K | ﹤0.01% |
1,600
+700
| +78% | +$4.89K |
|
7100
PUT
Byrna Technologies
BYRN
$98.3M
| $8.39K | ﹤0.01% |
500
-2,100
| -81% | -$40.9K |
|
Similar funds
Simplex Trading's Q4 2025 Portfolio in Review
As of Q4 2025, Simplex Trading held 10,526 positions worth $177B, down 9% from $195B the previous quarter. Its ten largest holdings account for 49% of the portfolio.
Simplex Trading withdrew a net $23.2B in Q4 2025, closing 2,184 positions and reducing 4,088 holdings. Its most notable exit was iShares Russell 2000 ETF, an estimated $149M position sold in full.
By sector, the portfolio is most concentrated in Technology at 0.59% of assets, down from 0.79% a quarter earlier, followed by Consumer Discretionary and Healthcare.
Against the trend, Simplex Trading opened a new position in Western Digital worth $58.9M.
- Simplex Trading's largest Q4 2025 buy was Western Digital: 341,762 shares worth $58.9M.
- Simplex Trading added most to Netflix in Q4 2025, an estimated $73.1M increase.
- Simplex Trading's biggest Q4 2025 reduction was NVIDIA, cutting an estimated $262M.
- Simplex Trading fully exited iShares Russell 2000 ETF in Q4 2025, selling an estimated $149M.
- Simplex Trading's ten largest holdings make up 49% of its $177B portfolio in Q4 2025.
- Simplex Trading opened 1,476 new positions and closed 2,184 in Q4 2025.
- Simplex Trading's portfolio value fell 9% quarter-over-quarter to $177B.
Based on Simplex Trading's 13F filing for Q4 2025, filed 11 Feb 2026.