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 | |
|---|---|---|---|---|---|---|
|
DFTX
3051
Definium Therapeutics
DFTX
$5.66B
| $646K | ﹤0.01% |
48,226
+7,061
| +17% | +$87.4K |
|
3052
Gold Royalty Corp
GROY
$609M
| $646K | ﹤0.01% |
159,791
+66,335
| +71% | +$254K |
|
3053
Red Cat Holdings
RCAT
$1.19B
| $643K | ﹤0.01% |
81,098
-11,300
| -12% | -$108K |
|
3054
CALL
Kingstone Companies
KINS
$285M
| $643K | ﹤0.01% |
38,200
+10,600
| +38% | +$161K |
|
3055
Zillow
ZG
$7.32B
| $641K | ﹤0.01% |
9,400
+9,314
| +10,830% | +$655K |
|
3056
ProShares Ultra S&P500
SSO
$7.72B
| $641K | ﹤0.01% |
11,069
-2,859
| -21% | -$164K |
|
3057
Argan
AGX
$7.61B
| $641K | ﹤0.01% |
2,045
-1,856
| -48% | -$589K |
|
3058
CALL
AtaiBeckley Inc
ATAI
$2.65B
| $640K | ﹤0.01% |
156,600
-14,000
| -8% | -$66.1K |
|
3059
Legend Biotech
LEGN
$3.73B
| $640K | ﹤0.01% |
+29,432
| New | +$843K |
|
3060
CALL
Smith & Wesson
SWBI
$666M
| $640K | ﹤0.01% |
64,800
-32,100
| -33% | -$310K |
|
3061
PUT
Old Republic International
ORI
$10.5B
| $639K | ﹤0.01% |
14,000
+4,200
| +43% | +$182K |
|
3062
PUT
Itaú Unibanco
ITUB
$92.3B
| $639K | ﹤0.01% |
89,200
+19,778
| +28% | +$141K |
|
3063
Whirlpool
WHR
$2.44B
| $639K | ﹤0.01% |
8,853
-16,548
| -65% | -$1.22M |
|
3064
CALL
Rani Therapeutics
RANI
$91M
| $638K | ﹤0.01% |
472,500
+461,100
| +4,045% | +$696K |
|
3065
UGI
UGI
$7.91B
| $635K | ﹤0.01% |
+16,971
| New | +$601K |
|
3066
CALL
Invivyd
IVVD
$180M
| $633K | ﹤0.01% |
256,400
+224,900
| +714% | +$468K |
|
3067
CALL
ICL Group
ICL
$6.65B
| $633K | ﹤0.01% |
110,900
+93,900
| +552% | +$544K |
|
3068
CALL
Vanguard Total Bond Market
BND
$158B
| $632K | ﹤0.01% |
8,600
+1,000
| +13% | +$74.4K |
|
3069
CALL
GoPro
GPRO
$119M
| $632K | ﹤0.01% |
448,400
-127,300
| -22% | -$231K |
|
3070
EyePoint Inc
EYPT
$1.04B
| $631K | ﹤0.01% |
34,525
+17,784
| +106% | +$252K |
|
3071
argenx
ARGX
$55.6B
| $631K | ﹤0.01% |
750
-49
| -6% | -$41.9K |
|
3072
PUT
TORM
TRMD
$3.05B
| $629K | ﹤0.01% |
32,100
+8,300
| +35% | +$175K |
|
3073
Ramaco Resources Class A
METC
$664M
| $628K | ﹤0.01% |
34,916
+3,965
| +13% | +$104K |
|
3074
Imperial Petroleum
IMPP
$217M
| $628K | ﹤0.01% |
173,506
-81,767
| -32% | -$402K |
|
3075
PUT
Invesco
IVZ
$13.3B
| $628K | ﹤0.01% |
23,900
-118,000
| -83% | -$2.88M |
|
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.