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 | |
|---|---|---|---|---|---|---|
4151
AtaiBeckley Inc
ATAI
$2.66B
| $217K | ﹤0.01% |
53,065
-84,577
| -61% | -$399K |
|
4152
PUT
MBIA
MBI
$275M
| $217K | ﹤0.01% |
30,300
-95,000
| -76% | -$687K |
|
4153
CALL
B&G Foods
BGS
$303M
| $217K | ﹤0.01% |
50,400
+17,800
| +55% | +$79.5K |
|
4154
PUT
National Grid
NGG
$79.3B
| $217K | ﹤0.01% |
2,800
-17,081
| -86% | -$1.28M |
|
4155
CALL
Nordson
NDSN
$16.4B
| $216K | ﹤0.01% |
+900
| New | +$211K |
|
4156
PUT
Parsons
PSN
$4.31B
| $216K | ﹤0.01% |
3,500
-25,900
| -88% | -$2.03M |
|
|
LOMA
4157
CALL
Loma Negra
LOMA
$1.34B
| $216K | ﹤0.01% |
+16,700
| New | +$178K |
|
4158
PUT
Crown Holdings
CCK
$13B
| $216K | ﹤0.01% |
2,100
-4,900
| -70% | -$477K |
|
4159
CALL
Concentrix
CNXC
$1.62B
| $216K | ﹤0.01% |
5,200
-45,600
| -90% | -$1.85M |
|
4160
First Internet Bancorp
INBK
$233M
| $216K | ﹤0.01% |
10,355
+10,295
| +17,158% | +$207K |
|
4161
PUT
Xponential Fitness
XPOF
$286M
| $216K | ﹤0.01% |
26,200
-12,200
| -32% | -$86.7K |
|
|
WYFI
4162
PUT
WhiteFiber Inc
WYFI
$795M
| $215K | ﹤0.01% |
13,600
-39,800
| -75% | -$984K |
|
4163
Mueller Industries
MLI
$14.5B
| $215K | ﹤0.01% |
3,742
+2,576
| +221% | +$139K |
|
4164
Cardlytics
CDLX
$22.2M
| $214K | ﹤0.01% |
18,638
-6,897
| -27% | -$107K |
|
4165
PUT
WisdomTree US Total Dividend Fund
DTD
$1.64B
| $214K | ﹤0.01% |
1,900
-1,500
| -44% | -$126K |
|
|
NEWP
4166
CALL
New Pacific Metals
NEWP
$809M
| $214K | ﹤0.01% |
61,000
+36,200
| +146% | +$99.1K |
|
4167
CALL
Lakeland Industries
LAKE
$108M
| $213K | ﹤0.01% |
24,100
+24,000
| +24,000% | +$337K |
|
|
XRN
4168
Chiron Real Estate Inc
XRN
$535M
| $213K | ﹤0.01% |
6,314
-969
| -13% | -$31.6K |
|
4169
PUT
Repligen
RGEN
$6.91B
| $213K | ﹤0.01% |
1,300
+100
| +8% | +$15.7K |
|
|
ZEPP
4170
PUT
Zepp Health
ZEPP
$63.8M
| $213K | ﹤0.01% |
7,900
+2,300
| +41% | +$82K |
|
4171
PUT
Jacobs Solutions
J
$16B
| $212K | ﹤0.01% |
1,600
+100
| +7% | +$14.7K |
|
|
BNCWW
4172
CALL
CEA Industries Inc Warrant
BNCWW
$51.9K
| $212K | ﹤0.01% |
33,000
-41,500
| -56% | -$4.67K |
|
4173
CALL
Innoviz Technologies
INVZ
$84.1M
| $212K | ﹤0.01% |
248,000
-17,600
| -7% | -$27.9K |
|
4174
PUT
Trimble
TRMB
$13.6B
| $212K | ﹤0.01% |
2,700
+2,000
| +286% | +$159K |
|
4175
PUT
Leonardo DRS
DRS
$12.4B
| $211K | ﹤0.01% |
6,200
-13,400
| -68% | -$494K |
|
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.