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 | |
|---|---|---|---|---|---|---|
3076
iShares MSCI United Kingdom ETF
EWU
$4.05B
| $627K | ﹤0.01% |
14,267
-18,391
| -56% | -$788K |
|
3077
PUT
Xylem
XYL
$28.6B
| $626K | ﹤0.01% |
4,600
+1,700
| +59% | +$245K |
|
3078
PUT
Korro Bio
KRRO
$155M
| $626K | ﹤0.01% |
+78,100
| New | +$1.83M |
|
3079
PUT
BellRing Brands
BRBR
$1.52B
| $625K | ﹤0.01% |
23,400
+10,000
| +75% | +$310K |
|
|
OS
3080
CALL
DELISTED
OneStream Inc
OS
| $625K | ﹤0.01% |
34,000
+7,300
| +27% | +$139K |
|
3081
CALL
Frontier Group Holdings
ULCC
$1.4B
| $625K | ﹤0.01% |
132,600
+107,600
| +430% | +$477K |
|
3082
PUT
Asana
ASAN
$1.79B
| $622K | ﹤0.01% |
45,400
-41,100
| -48% | -$565K |
|
3083
CALL
iShares Convertible Bond ETF
ICVT
$7.21B
| $621K | ﹤0.01% |
17,400
-11,400
| -40% | -$1.15M |
|
3084
Equinix
EQIX
$103B
| $621K | ﹤0.01% |
810
+583
| +257% | +$457K |
|
|
PCH
3085
CALL
DELISTED
PotlatchDeltic
PCH
| $621K | ﹤0.01% |
15,600
+14,700
| +1,633% | +$595K |
|
3086
Stanley Black & Decker
SWK
$14.6B
| $619K | ﹤0.01% |
8,328
-7,192
| -46% | -$506K |
|
3087
PUT
Matsons
MATX
$6.22B
| $618K | ﹤0.01% |
5,000
-36,000
| -88% | -$3.87M |
|
|
CIVI
3088
PUT
DELISTED
Civitas Resources
CIVI
| $618K | ﹤0.01% |
22,800
-125,600
| -85% | -$3.63M |
|
3089
CALL
Boot Barn
BOOT
$4.71B
| $618K | ﹤0.01% |
3,500
+300
| +9% | +$56K |
|
3090
Arteris
AIP
$1.4B
| $616K | ﹤0.01% |
39,718
+38,111
| +2,372% | +$552K |
|
3091
Albertsons Companies
ACI
$5.57B
| $615K | ﹤0.01% |
+35,827
| New | +$639K |
|
3092
Capital Southwest
CSWC
$1.46B
| $615K | ﹤0.01% |
27,754
+12,177
| +78% | +$257K |
|
3093
PUT
Graphic Packaging
GPK
$3.3B
| $614K | ﹤0.01% |
40,800
+40,400
| +10,100% | +$664K |
|
3094
CALL
Aurinia Pharmaceuticals
AUPH
$1.96B
| $614K | ﹤0.01% |
38,500
-89,400
| -70% | -$1.27M |
|
3095
CALL
Cooper-Standard Automotive
CPS
$508M
| $614K | ﹤0.01% |
18,700
-14,000
| -43% | -$456K |
|
3096
CALL
Adient
ADNT
$1.62B
| $613K | ﹤0.01% |
32,000
+3,700
| +13% | +$77.8K |
|
3097
PUT
Regenxbio
RGNX
$622M
| $613K | ﹤0.01% |
42,600
-10,700
| -20% | -$133K |
|
3098
AppFolio
APPF
$5.98B
| $612K | ﹤0.01% |
2,632
+2,198
| +506% | +$522K |
|
3099
PUT
Church & Dwight Co
CHD
$23.4B
| $612K | ﹤0.01% |
7,300
-9,000
| -55% | -$769K |
|
3100
CALL
Otis Worldwide
OTIS
$27.9B
| $611K | ﹤0.01% |
7,000
-12,500
| -64% | -$1.12M |
|
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.