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 | |
|---|---|---|---|---|---|---|
1901
PUT
The RealReal
REAL
$1.34B
| $2.21M | ﹤0.01% |
140,100
+68,300
| +95% | +$892K |
|
1902
Las Vegas Sands
LVS
$30.5B
| $2.21M | ﹤0.01% |
33,897
+25,299
| +294% | +$1.55M |
|
1903
CALL
Star Bulk Carriers
SBLK
$3.14B
| $2.2M | ﹤0.01% |
114,400
-5,900
| -5% | -$110K |
|
1904
BWX Technologies
BWXT
$16B
| $2.2M | ﹤0.01% |
12,710
+3,274
| +35% | +$614K |
|
1905
JetBlue
JBLU
$1.96B
| $2.19M | ﹤0.01% |
481,326
+11,624
| +2% | +$53K |
|
|
GTLS
1906
CALL
DELISTED
Chart Industries
GTLS
| $2.19M | ﹤0.01% |
10,600
+300
| +3% | +$60.8K |
|
|
AMRZ
1907
PUT
Amrize Ltd
AMRZ
$27.3B
| $2.18M | ﹤0.01% |
40,400
+16,500
| +69% | +$842K |
|
1908
Comfort Systems
FIX
$61B
| $2.18M | ﹤0.01% |
2,338
+1,321
| +130% | +$1.22M |
|
1909
CALL
LivePerson
LPSN
$18.9M
| $2.18M | ﹤0.01% |
563,300
+529,147
| +1,549% | +$2.94M |
|
1910
PUT
Ambarella
AMBA
$2.99B
| $2.17M | ﹤0.01% |
30,700
-25,300
| -45% | -$2.04M |
|
1911
CALL
Pitney Bowes
PBI
$2.42B
| $2.17M | ﹤0.01% |
205,500
-46,300
| -18% | -$480K |
|
1912
CALL
GeneDx Holdings
WGS
$1.75B
| $2.17M | ﹤0.01% |
16,700
-7,600
| -31% | -$1.04M |
|
1913
CALL
iShares iBonds 2030 Term High Yield and Income ETF
IBHJ
$151M
| $2.17M | ﹤0.01% |
22,100
+16,000
| +262% | +$425K |
|
|
ABK
1914
CALL
DELISTED
Ambac Financial Group
ABK
| $2.17M | ﹤0.01% |
278,700
-74,400
| -21% | -$579K |
|
1915
CALL
Waters Corp
WAT
$36.8B
| $2.17M | ﹤0.01% |
5,700
+4,000
| +235% | +$1.47M |
|
1916
CALL
Idexx Laboratories
IDXX
$42.9B
| $2.16M | ﹤0.01% |
3,200
+1,100
| +52% | +$749K |
|
1917
Sony
SONY
$123B
| $2.16M | ﹤0.01% |
+84,514
| New | +$2.37M |
|
1918
Best Buy
BBY
$18B
| $2.16M | ﹤0.01% |
32,273
+27,348
| +555% | +$2.09M |
|
1919
PUT
Urban Outfitters
URBN
$5.99B
| $2.16M | ﹤0.01% |
28,700
-17,900
| -38% | -$1.27M |
|
1920
PUT
GoDaddy
GDDY
$12.3B
| $2.16M | ﹤0.01% |
17,400
+7,000
| +67% | +$906K |
|
1921
Shopify
SHOP
$148B
| $2.16M | ﹤0.01% |
13,407
+12,513
| +1,400% | +$2.01M |
|
1922
Viasat
VSAT
$9.79B
| $2.16M | ﹤0.01% |
62,568
+22,292
| +55% | +$787K |
|
1923
iShares Russell 1000 Growth ETF
IWF
$122B
| $2.15M | ﹤0.01% |
18,212
+3,348
| +23% | +$397K |
|
1924
PUT
Cal-Maine
CALM
$4.28B
| $2.15M | ﹤0.01% |
27,000
-2,500
| -8% | -$220K |
|
1925
Suncor Energy
SU
$77.7B
| $2.14M | ﹤0.01% |
+48,290
| New | +$2.04M |
|
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.