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 | |
|---|---|---|---|---|---|---|
4626
Granite Construction
GVA
$5.16B
| $139K | ﹤0.01% |
+1,203
| New | +$129K |
|
4627
CALL
Vitesse Energy
VTS
$644M
| $139K | ﹤0.01% |
7,200
-4,400
| -38% | -$93.9K |
|
4628
CALL
Diodes
DIOD
$3.5B
| $138K | ﹤0.01% |
+2,800
| New | +$142K |
|
4629
Alta Equipment Group
ALTG
$194M
| $138K | ﹤0.01% |
30,033
+4,024
| +15% | +$22.1K |
|
|
CSGS
4630
PUT
DELISTED
CSG Systems International
CSGS
| $138K | ﹤0.01% |
+1,800
| New | +$133K |
|
4631
CALL
AMC Global Media
AMCX
$450M
| $138K | ﹤0.01% |
14,500
-24,200
| -63% | -$204K |
|
4632
PUT
Stratasys
SSYS
$666M
| $138K | ﹤0.01% |
15,900
| – | – |
|
4633
Teradata
TDC
$2.88B
| $138K | ﹤0.01% |
4,533
+1,425
| +46% | +$37.3K |
|
|
SF
4634
CALL
Stifel
SF
$12.4B
| $138K | ﹤0.01% |
1,650
-1,200
| -42% | -$95.9K |
|
|
WTMY
4635
CALL
WisdomTree High Income Laddered Municipal Fund
WTMY
$5.01M
| $138K | ﹤0.01% |
2,300
-400
| -15% | -$10.2K |
|
4636
CALL
Lincoln Educational Services
LINC
$1.38B
| $138K | ﹤0.01% |
5,700
+5,000
| +714% | +$109K |
|
4637
iShares MSCI World ETF
URTH
$7.83B
| $137K | ﹤0.01% |
740
+376
| +103% | +$69.2K |
|
4638
PUT
NewMarket
NEU
$7.24B
| $137K | ﹤0.01% |
200
-300
| -60% | -$229K |
|
4639
CALL
Paylocity
PCTY
$7.75B
| $137K | ﹤0.01% |
900
+200
| +29% | +$29.8K |
|
4640
Cullinan Oncology
CGEM
$1.06B
| $137K | ﹤0.01% |
13,253
-32
| -0.2% | -$289 |
|
4641
PUT
Sturm, Ruger & Co
RGR
$603M
| $137K | ﹤0.01% |
4,200
+1,200
| +40% | +$44.5K |
|
4642
CALL
Alkermes
ALKS
$8.11B
| $137K | ﹤0.01% |
4,900
-1,600
| -25% | -$47.9K |
|
|
NIU
4643
CALL
Niu Technologies
NIU
$200M
| $137K | ﹤0.01% |
45,200
+44,400
| +5,550% | +$172K |
|
4644
SLM Corp
SLM
$4.83B
| $137K | ﹤0.01% |
+5,057
| New | +$139K |
|
4645
CALL
Tronox
TROX
$967M
| $137K | ﹤0.01% |
32,800
-8,600
| -21% | -$32.8K |
|
|
TIC
4646
TIC Solutions Inc
TIC
$1.59B
| $137K | ﹤0.01% |
13,516
-76,545
| -85% | -$852K |
|
4647
Healthpeak Properties
DOC
$15.5B
| $137K | ﹤0.01% |
8,496
+6,656
| +362% | +$117K |
|
4648
WillScot Mobile Mini Holdings
WSC
$4.37B
| $136K | ﹤0.01% |
7,244
-10,594
| -59% | -$214K |
|
4649
CALL
Rayonier
RYN
$6.67B
| $136K | ﹤0.01% |
6,300
-10,166
| -62% | -$230K |
|
|
GTM
4650
PUT
ZoomInfo Technologies
GTM
$1.03B
| $136K | ﹤0.01% |
13,400
-529,500
| -98% | -$5.45M |
|
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.