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 | |
|---|---|---|---|---|---|---|
|
WCC
4776
PUT
WESCO International
WCC
$16.7B
| $122K | ﹤0.01% |
500
-200
| -29% | -$49.1K |
|
|
UPB
4777
PUT
Upstream Bio Inc
UPB
$358M
| $122K | ﹤0.01% |
4,500
-4,000
| -47% | -$99.6K |
|
4778
American Homes 4 Rent
AMH
$11.9B
| $122K | ﹤0.01% |
3,798
+1,730
| +84% | +$55.5K |
|
4779
The Joint Corp
JYNT
$119M
| $122K | ﹤0.01% |
13,977
+5,005
| +56% | +$42.5K |
|
4780
CALL
Hyster-Yale Materials Handling
HY
$600M
| $122K | ﹤0.01% |
4,100
+3,800
| +1,267% | +$125K |
|
|
BAI
4781
iShares A.I. Innovation and Tech Active ETF
BAI
$12.5B
| $122K | ﹤0.01% |
3,657
+3,070
| +523% | +$106K |
|
4782
Sprott Junior Copper Miners ETF
COPJ
$146M
| $121K | ﹤0.01% |
+3,092
| New | +$113K |
|
|
NMAX
4783
Newsmax Inc
NMAX
$991M
| $121K | ﹤0.01% |
15,698
-17,551
| -53% | -$169K |
|
4784
iShares US Treasury Bond ETF
GOVT
$43.7B
| $121K | ﹤0.01% |
+5,268
| New | +$122K |
|
4785
CALL
WPP
WPP
$4.41B
| $121K | ﹤0.01% |
5,400
-9,600
| -64% | -$206K |
|
4786
CALL
Embecta
EMBC
$217M
| $121K | ﹤0.01% |
10,200
+1,300
| +15% | +$17.1K |
|
4787
CALL
Clean Energy Fuels
CLNE
$425M
| $121K | ﹤0.01% |
57,700
+32,000
| +125% | +$78.3K |
|
4788
PUT
Halozyme
HALO
$9.88B
| $121K | ﹤0.01% |
1,800
-13,500
| -88% | -$908K |
|
4789
Targa Resources
TRGP
$57.6B
| $121K | ﹤0.01% |
656
+553
| +537% | +$93.1K |
|
4790
PUT
Federal Realty Investment Trust
FRT
$10.7B
| $121K | ﹤0.01% |
1,200
-2,500
| -68% | -$246K |
|
4791
PUT
Woodward
WWD
$21.2B
| $121K | ﹤0.01% |
400
-300
| -43% | -$82.6K |
|
4792
PUT
Tandem Diabetes Care
TNDM
$1.3B
| $121K | ﹤0.01% |
5,500
-19,300
| -78% | -$348K |
|
4793
TransAlta
TAC
$4.06B
| $121K | ﹤0.01% |
+9,547
| New | +$143K |
|
4794
Cavco Industries
CVCO
$4.33B
| $121K | ﹤0.01% |
204
+166
| +437% | +$94.1K |
|
4795
CALL
A.O. Smith
AOS
$8.24B
| $120K | ﹤0.01% |
+1,800
| New | +$122K |
|
|
PLYM
4796
CALL
DELISTED
Plymouth Industrial REIT
PLYM
| $120K | ﹤0.01% |
5,500
+2,700
| +96% | +$59.3K |
|
4797
PUT
Cato Corp
CATO
$66.5M
| $120K | ﹤0.01% |
38,900
+2,000
| +5% | +$7.35K |
|
4798
PUT
Atkore
ATKR
$2.4B
| $120K | ﹤0.01% |
1,900
-1,200
| -39% | -$78.3K |
|
4799
Replimune Group
REPL
$455M
| $120K | ﹤0.01% |
12,357
-138,089
| -92% | -$1.17M |
|
|
HI
4800
DELISTED
Hillenbrand
HI
| $120K | ﹤0.01% |
3,776
-8,169
| -68% | -$252K |
|
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.