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 | |
|---|---|---|---|---|---|---|
6126
PUT
Verastem
VSTM
$510M
| $29.3K | ﹤0.01% |
3,800
+3,400
| +850% | +$30.3K |
|
6127
CALL
Ashland
ASH
$3.33B
| $29.3K | ﹤0.01% |
500
-100
| -17% | -$5.29K |
|
|
KRMN
6128
PUT
Karman Holdings
KRMN
$6.38B
| $29.3K | ﹤0.01% |
400
-6,000
| -94% | -$434K |
|
|
SEM
6129
DELISTED
Select Medical
SEM
| $29.3K | ﹤0.01% |
1,970
+1,121
| +132% | +$15.8K |
|
6130
PUT
NiSource
NI
$21.3B
| $29.2K | ﹤0.01% |
700
-102,700
| -99% | -$4.39M |
|
6131
PUT
Mercury Systems
MRCY
$5.83B
| $29.2K | ﹤0.01% |
400
| – | – |
|
6132
One Stop Systems
OSS
$303M
| $29.1K | ﹤0.01% |
4,058
+1,721
| +74% | +$10.2K |
|
6133
CALL
Limoneira
LMNR
$235M
| $29K | ﹤0.01% |
2,300
-3,800
| -62% | -$53.7K |
|
6134
CALL
Old National Bancorp
ONB
$10.2B
| $29K | ﹤0.01% |
1,300
-6,400
| -83% | -$138K |
|
6135
PUT
American States Water
AWR
$3.36B
| $29K | ﹤0.01% |
400
+200
| +100% | +$14.7K |
|
6136
PUT
CareTrust REIT
CTRE
$9.91B
| $28.9K | ﹤0.01% |
800
+300
| +60% | +$10.8K |
|
6137
CALL
Janus Henderson Small Cap Growth Alpha ETF
JSML
$361M
| $28.9K | ﹤0.01% |
600
| – | – |
|
6138
PUT
Reliance Steel & Aluminium
RS
$20.7B
| $28.9K | ﹤0.01% |
100
-400
| -80% | -$112K |
|
6139
PUT
Ryanair
RYAAY
$30.4B
| $28.9K | ﹤0.01% |
400
-400
| -50% | -$26K |
|
6140
PUT
Aspen Aerogels
ASPN
$384M
| $28.9K | ﹤0.01% |
10,200
-26,500
| -72% | -$137K |
|
6141
PUT
Q2 Holdings
QTWO
$3.8B
| $28.9K | ﹤0.01% |
400
-200
| -33% | -$13.7K |
|
6142
CALL
SandRidge Energy
SD
$514M
| $28.9K | ﹤0.01% |
2,000
-14,500
| -88% | -$192K |
|
|
PTRN
6143
CALL
Pattern Group Inc
PTRN
$4.07B
| $28.9K | ﹤0.01% |
+2,500
| New | +$36.4K |
|
6144
PUT
Brixmor Property Group
BRX
$9.67B
| $28.8K | ﹤0.01% |
1,100
-400
| -27% | -$10.6K |
|
6145
CALL
Pulse Biosciences
PLSE
$2.43B
| $28.8K | ﹤0.01% |
2,100
+1,800
| +600% | +$28K |
|
|
GDEN
6146
DELISTED
Golden Entertainment
GDEN
| $28.8K | ﹤0.01% |
+1,059
| New | +$27.4K |
|
6147
CALL
ProFrac Holding
ACDC
$731M
| $28.8K | ﹤0.01% |
7,400
-23,600
| -76% | -$96.4K |
|
6148
CALL
Arq
ARQ
$84.6M
| $28.8K | ﹤0.01% |
8,800
-28,900
| -77% | -$141K |
|
6149
PUT
Cambria Tail Risk ETF
TAIL
$147M
| $28.7K | ﹤0.01% |
2,500
+1,700
| +213% | +$20.1K |
|
6150
CALL
RLX Technology
RLX
$2.47B
| $28.7K | ﹤0.01% |
12,300
-22,600
| -65% | -$54.1K |
|
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.