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 | |
|---|---|---|---|---|---|---|
6651
CALL
Wolverine World Wide
WWW
$1.61B
| $16.3K | ﹤0.01% |
900
-13,800
| -94% | -$279K |
|
|
SJT
6652
CALL
San Juan Basin Royalty Trust
SJT
$117M
| $16.3K | ﹤0.01% |
2,900
-41,700
| -93% | -$241K |
|
|
EFC
6653
PUT
Ellington Financial
EFC
$1.67B
| $16.3K | ﹤0.01% |
1,200
-24,000
| -95% | -$326K |
|
6654
CALL
CS Disco
LAW
$250M
| $16.3K | ﹤0.01% |
2,100
+1,800
| +600% | +$12.7K |
|
6655
PUT
Astronics
ATRO
$3.43B
| $16.3K | ﹤0.01% |
360
-1,080
| -75% | -$45.3K |
|
|
XAIX
6656
Xtrackers Artificial Intelligence and Big Data ETF
XAIX
$162M
| $16.3K | ﹤0.01% |
+379
| New | +$16.1K |
|
6657
PUT
NETSCOUT
NTCT
$2.96B
| $16.2K | ﹤0.01% |
+600
| New | +$16.2K |
|
6658
CALL
Full House Resorts
FLL
$80.1M
| $16.2K | ﹤0.01% |
6,200
| – | – |
|
6659
PUT
RELX
RELX
$61.8B
| $16.2K | ﹤0.01% |
400
-100
| -20% | -$4.27K |
|
6660
Newmark Group
NMRK
$2.66B
| $16.1K | ﹤0.01% |
931
-6,858
| -88% | -$120K |
|
6661
CALL
iShares S&P GSCI Commodity-Indexed Trust
GSG
$998M
| $16.1K | ﹤0.01% |
700
| – | – |
|
6662
CALL
Voyager Therapeutics
VYGR
$183M
| $16.1K | ﹤0.01% |
4,100
-85,300
| -95% | -$377K |
|
6663
First Trust NYSE Arca Biotechnology Index Fund
FBT
$2.78B
| $16.1K | ﹤0.01% |
+78
| New | +$15.6K |
|
6664
Virtus Reaves Utilities ETF
UTES
$1.33B
| $16.1K | ﹤0.01% |
+204
| New | +$16.8K |
|
6665
PUT
KBR
KBR
$4.62B
| $16.1K | ﹤0.01% |
400
-800
| -67% | -$34.3K |
|
6666
PUT
CBRE Group
CBRE
$42.5B
| $16.1K | ﹤0.01% |
100
-3,000
| -97% | -$472K |
|
6667
Gates Industrial Corporation Ltd.
GTES
$7.08B
| $16K | ﹤0.01% |
747
-15,333
| -95% | -$354K |
|
6668
CALL
Mercer International
MERC
$42.3M
| $16K | ﹤0.01% |
8,100
-2,100
| -21% | -$4.42K |
|
6669
CALL
Dentsply Sirona
XRAY
$2.68B
| $16K | ﹤0.01% |
1,400
-33,000
| -96% | -$387K |
|
6670
IES Holdings
IESC
$14.8B
| $15.9K | ﹤0.01% |
41
-670
| -94% | -$269K |
|
6671
PUT
LendingTree
TREE
$447M
| $15.9K | ﹤0.01% |
300
-33,100
| -99% | -$1.86M |
|
6672
CALL
A10 Networks
ATEN
$2.13B
| $15.9K | ﹤0.01% |
900
-2,300
| -72% | -$40.7K |
|
6673
CALL
Disc Medicine
IRON
$2.96B
| $15.9K | ﹤0.01% |
200
+100
| +100% | +$8.45K |
|
6674
CALL
NNN REIT
NNN
$9.04B
| $15.9K | ﹤0.01% |
400
-11,200
| -97% | -$459K |
|
|
QUBX
6675
Tradr 2X Long QUBT Daily ETF
QUBX
$23.4M
| $15.8K | ﹤0.01% |
+724
| New | +$41.3K |
|
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.