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 | |
|---|---|---|---|---|---|---|
5926
PUT
Virtu Financial
VIRT
$5.11B
| $36.7K | ﹤0.01% |
1,100
-23,100
| -95% | -$790K |
|
5927
PUT
BlackRock US Equity Factor Rotation ETF
DYNF
$38.6B
| $36.6K | ﹤0.01% |
1,100
+800
| +267% | +$48.1K |
|
5928
Boise Cascade
BCC
$2.69B
| $36.6K | ﹤0.01% |
497
-6,750
| -93% | -$492K |
|
5929
PUT
Sprinklr
CXM
$1.49B
| $36.6K | ﹤0.01% |
4,700
+100
| +2% | +$761 |
|
5930
Roper Technologies
ROP
$38.8B
| $36.5K | ﹤0.01% |
82
-52
| -39% | -$24.1K |
|
5931
CALL
UFP Industries
UFPI
$4.9B
| $36.4K | ﹤0.01% |
+400
| New | +$36.6K |
|
5932
Banco Santander Chile
BSAC
$16.3B
| $36.3K | ﹤0.01% |
1,168
+168
| +17% | +$4.89K |
|
5933
PUT
Gladstone Investment Corp
GAIN
$643M
| $36.3K | ﹤0.01% |
2,600
-1,200
| -32% | -$16.6K |
|
5934
ARKO Corp
ARKO
$896M
| $36.3K | ﹤0.01% |
+7,993
| New | +$35.8K |
|
5935
PUT
PAR Technology
PAR
$699M
| $36.3K | ﹤0.01% |
1,000
-1,200
| -55% | -$43.3K |
|
|
GOOD
5936
PUT
Gladstone Commercial Corp
GOOD
$605M
| $36.3K | ﹤0.01% |
3,400
-3,100
| -48% | -$34.4K |
|
5937
PUT
Stem
STEM
$48.4M
| $36.3K | ﹤0.01% |
9,000
-16,500
| -65% | -$316K |
|
|
SEPN
5938
CALL
Septerna Inc
SEPN
$1.55B
| $36.2K | ﹤0.01% |
1,300
-1,600
| -55% | -$38.2K |
|
|
PRA
5939
CALL
DELISTED
ProAssurance
PRA
| $36.2K | ﹤0.01% |
1,500
+1,000
| +200% | +$24K |
|
5940
CALL
Pliant Therapeutics
PLRX
$64.4M
| $36.2K | ﹤0.01% |
+29,700
| New | +$44.6K |
|
|
NIU
5941
Niu Technologies
NIU
$203M
| $36.2K | ﹤0.01% |
11,949
-4,559
| -28% | -$17.6K |
|
5942
CALL
Q2 Holdings
QTWO
$3.8B
| $36.1K | ﹤0.01% |
500
-200
| -29% | -$13.7K |
|
5943
PUT
Alector
ALEC
$168M
| $36K | ﹤0.01% |
23,100
-27,100
| -54% | -$48.1K |
|
5944
CareCloud
CCLD
$104M
| $36K | ﹤0.01% |
+12,336
| New | +$39K |
|
|
PCH
5945
DELISTED
PotlatchDeltic
PCH
| $36K | ﹤0.01% |
905
-11,723
| -93% | -$475K |
|
5946
Simulations Plus
SLP
$369M
| $35.9K | ﹤0.01% |
1,971
-2,289
| -54% | -$40.2K |
|
|
SLN
5947
PUT
Silence Therapeutics
SLN
$495M
| $35.9K | ﹤0.01% |
5,900
+4,600
| +354% | +$29.5K |
|
5948
Caledonia Mining Corp
CMCL
$355M
| $35.8K | ﹤0.01% |
1,368
-1,490
| -52% | -$43.8K |
|
5949
CALL
Alarm.com
ALRM
$2.71B
| $35.7K | ﹤0.01% |
700
| – | – |
|
|
SFIX
5950
PUT
Stitch Fix
SFIX
$536M
| $35.7K | ﹤0.01% |
6,800
-15,800
| -70% | -$72.1K |
|
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.