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 | |
|---|---|---|---|---|---|---|
3401
ADT
ADT
$5.35B
| $452K | ﹤0.01% |
+55,981
| New | +$465K |
|
3402
CALL
Kirby Corp
KEX
$7.66B
| $452K | ﹤0.01% |
4,100
+400
| +11% | +$40.7K |
|
3403
CALL
Western Union
WU
$2.61B
| $450K | ﹤0.01% |
48,300
-56,700
| -54% | -$501K |
|
3404
PUT
InfraCap MLP ETF
AMZA
$464M
| $450K | ﹤0.01% |
20,100
+15,200
| +310% | +$600K |
|
3405
PUT
Spire Global
SPIR
$436M
| $449K | ﹤0.01% |
59,900
+31,700
| +112% | +$310K |
|
3406
Idacorp
IDA
$8.24B
| $449K | ﹤0.01% |
3,549
+2,927
| +471% | +$381K |
|
3407
O-I Glass
OI
$1.45B
| $448K | ﹤0.01% |
30,331
+8,439
| +39% | +$112K |
|
3408
CALL
BRC Group Holdings
RILY
$269M
| $447K | ﹤0.01% |
95,700
-10,600
| -10% | -$52.5K |
|
3409
CALL
Children's Place
PLCE
$54.3M
| $446K | ﹤0.01% |
112,100
-155,200
| -58% | -$1.11M |
|
3410
Parker-Hannifin
PH
$125B
| $446K | ﹤0.01% |
507
+238
| +88% | +$195K |
|
3411
Payoneer
PAYO
$2.42B
| $445K | ﹤0.01% |
79,242
+47,125
| +147% | +$272K |
|
3412
PUT
Atour Lifestyle Holdings
ATAT
$4.75B
| $445K | ﹤0.01% |
11,300
+6,200
| +122% | +$243K |
|
|
SFIX
3413
CALL
Stitch Fix
SFIX
$556M
| $445K | ﹤0.01% |
84,800
+15,200
| +22% | +$69.3K |
|
3414
CALL
Black Hills Corp
BKH
$5.73B
| $444K | ﹤0.01% |
6,400
+1,500
| +31% | +$101K |
|
|
SFIX
3415
Stitch Fix
SFIX
$556M
| $443K | ﹤0.01% |
84,410
+8,406
| +11% | +$38.3K |
|
3416
CALL
Genuine Parts
GPC
$17.9B
| $443K | ﹤0.01% |
3,600
-29,700
| -89% | -$3.84M |
|
|
VTEL
3417
PUT
Vanguard Long-Term Tax-Exempt Bond ETF
VTEL
$282M
| $443K | ﹤0.01% |
8,800
+7,600
| +633% | +$789K |
|
3418
CALL
Guidewire Software
GWRE
$13.2B
| $442K | ﹤0.01% |
2,200
-4,800
| -69% | -$1.06M |
|
3419
PUT
Compass
COMP
$8.86B
| $442K | ﹤0.01% |
41,800
-73,200
| -64% | -$668K |
|
3420
PUT
Thor Industries
THO
$4.2B
| $441K | ﹤0.01% |
4,300
-19,400
| -82% | -$2.02M |
|
3421
CALL
FormFactor
FORM
$6.89B
| $441K | ﹤0.01% |
7,900
-1,400
| -15% | -$70.5K |
|
3422
Immersion
IMMR
$257M
| $440K | ﹤0.01% |
64,764
+24,449
| +61% | +$166K |
|
3423
Dentsply Sirona
XRAY
$2.68B
| $439K | ﹤0.01% |
38,423
+4,256
| +12% | +$50K |
|
3424
CALL
Inspired Entertainment
INSE
$187M
| $439K | ﹤0.01% |
46,900
+24,800
| +112% | +$209K |
|
3425
PUT
Bentley Systems
BSY
$10.9B
| $439K | ﹤0.01% |
11,500
-1,500
| -12% | -$68.4K |
|
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.