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 | |
|---|---|---|---|---|---|---|
5376
ProShares Short 20+ Year Treasury ETF
TBF
$87.9M
| $67.8K | ﹤0.01% |
+2,810
| New | +$66.6K |
|
5377
PUT
Immuneering
IMRX
$267M
| $67.8K | ﹤0.01% |
+10,300
| New | +$66.1K |
|
5378
Acacia Research
ACTG
$428M
| $67.6K | ﹤0.01% |
18,081
+13,659
| +309% | +$49K |
|
5379
CALL
Immunic
IMUX
$190M
| $67.6K | ﹤0.01% |
12,660
-13,310
| -51% | -$97.5K |
|
5380
PUT
Dycom Industries
DY
$12B
| $67.6K | ﹤0.01% |
200
+100
| +100% | +$31.5K |
|
5381
PUT
Sana Biotechnology
SANA
$871M
| $67.6K | ﹤0.01% |
16,600
-43,800
| -73% | -$196K |
|
5382
CALL
Qiagen
QGEN
$8.54B
| $67.5K | ﹤0.01% |
1,500
-37,900
| -96% | -$1.75M |
|
5383
CALL
Carlyle Secured Lending
CGBD
$694M
| $67.4K | ﹤0.01% |
5,400
-2,200
| -29% | -$27.4K |
|
5384
CALL
Timken Company
TKR
$9.56B
| $67.3K | ﹤0.01% |
800
-800
| -50% | -$63.6K |
|
5385
CALL
Appian
APPN
$1.98B
| $67.3K | ﹤0.01% |
1,900
+800
| +73% | +$28.5K |
|
5386
PUT
Jones Lang LaSalle
JLL
$16.3B
| $67.3K | ﹤0.01% |
200
-100
| -33% | -$31.3K |
|
|
EMPD
5387
PUT
Empery Digital
EMPD
$79.8M
| $67.1K | ﹤0.01% |
14,700
-7,100
| -33% | -$41.5K |
|
5388
Green Dot
GDOT
$743M
| $67.1K | ﹤0.01% |
5,238
-26,264
| -83% | -$326K |
|
5389
CALL
Atmos Energy
ATO
$28.8B
| $67.1K | ﹤0.01% |
400
-3,400
| -89% | -$588K |
|
5390
PUT
Global Partners
GLP
$1.68B
| $67K | ﹤0.01% |
1,600
-600
| -27% | -$26.4K |
|
5391
ProShares Short Ether Strategy ETF
SETH
$15.6M
| $66.9K | ﹤0.01% |
1,594
+1,531
| +2,430% | +$59.3K |
|
5392
Loar Holdings
LOAR
$6.41B
| $66.8K | ﹤0.01% |
+983
| New | +$71.7K |
|
5393
CALL
Synaptics
SYNA
$4.19B
| $66.6K | ﹤0.01% |
900
-1,500
| -63% | -$105K |
|
5394
CALL
Grand Canyon Education
LOPE
$3.79B
| $66.5K | ﹤0.01% |
+400
| New | +$72.3K |
|
5395
Vishay Precision Group
VPG
$1.22B
| $66.4K | ﹤0.01% |
+1,724
| New | +$61K |
|
5396
PUT
Nomad Foods
NOMD
$1.66B
| $66.3K | ﹤0.01% |
5,300
+100
| +2% | +$1.22K |
|
5397
CALL
NCR Voyix
VYX
$1.14B
| $66.3K | ﹤0.01% |
6,500
+2,100
| +48% | +$22.8K |
|
5398
Cactus
WHD
$5.21B
| $66.2K | ﹤0.01% |
+1,449
| New | +$60.6K |
|
5399
PUT
Spire
SR
$4.72B
| $66.2K | ﹤0.01% |
800
+600
| +300% | +$51.2K |
|
|
IMMP
5400
CALL
Immutep
IMMP
$56.3M
| $66.1K | ﹤0.01% |
23,100
+7,200
| +45% | +$15.2K |
|
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.