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 | |
|---|---|---|---|---|---|---|
|
TRON
4751
PUT
Tron Inc
TRON
$702M
| $125K | ﹤0.01% |
100,600
+68,900
| +217% | +$155K |
|
4752
PUT
Upbound Group
UPBD
$1.17B
| $125K | ﹤0.01% |
7,100
+5,300
| +294% | +$102K |
|
4753
CALL
Martin Marietta Materials
MLM
$32.4B
| $125K | ﹤0.01% |
200
-1,000
| -83% | -$622K |
|
|
4754
PUT
Martin Marietta Materials
MLM
$32.4B
| $125K | ﹤0.01% |
200
-100
| -33% | -$62.2K |
|
4755
PUT
WillScot Mobile Mini Holdings
WSC
$4.35B
| $124K | ﹤0.01% |
6,600
-1,900
| -22% | -$38.3K |
|
|
PMT
4756
CALL
PennyMac Mortgage Investment
PMT
$812M
| $124K | ﹤0.01% |
9,900
-1,800
| -15% | -$22.4K |
|
4757
PUT
Grocery Outlet
GO
$906M
| $124K | ﹤0.01% |
12,300
-46,900
| -79% | -$590K |
|
|
TGNA
4758
PUT
DELISTED
TEGNA Inc
TGNA
| $124K | ﹤0.01% |
6,400
-237,800
| -97% | -$4.7M |
|
|
CAI
4759
Caris Life Sciences
CAI
$4.55B
| $124K | ﹤0.01% |
4,599
+616
| +15% | +$17.3K |
|
4760
PUT
Capital Southwest
CSWC
$1.47B
| $124K | ﹤0.01% |
5,600
+200
| +4% | +$4.22K |
|
4761
CALL
Amplitude
AMPL
$1.14B
| $124K | ﹤0.01% |
10,700
-38,100
| -78% | -$401K |
|
|
LNW
4762
PUT
DELISTED
Light & Wonder
LNW
| $124K | ﹤0.01% |
1,200
-700
| -37% | -$55.1K |
|
|
JHG
4763
PUT
DELISTED
Janus Henderson
JHG
| $124K | ﹤0.01% |
+2,600
| New | +$115K |
|
4764
CALL
Ichor Holdings
ICHR
$2.61B
| $123K | ﹤0.01% |
6,700
-36,200
| -84% | -$671K |
|
4765
Sabre
SABR
$739M
| $123K | ﹤0.01% |
90,760
+41,700
| +85% | +$71.8K |
|
|
KRMN
4766
Karman Holdings
KRMN
$6.26B
| $123K | ﹤0.01% |
+1,685
| New | +$122K |
|
4767
CALL
KNOT Offshore Partners
KNOP
$358M
| $123K | ﹤0.01% |
11,900
+5,000
| +72% | +$48.4K |
|
4768
Transportadora de Gas del Sur
TGS
$4.73B
| $123K | ﹤0.01% |
3,955
+3,360
| +565% | +$95K |
|
|
NFGC
4769
PUT
New Found Gold
NFGC
$549M
| $123K | ﹤0.01% |
41,400
+40,300
| +3,664% | +$98.9K |
|
4770
CALL
AMN Healthcare
AMN
$1.35B
| $123K | ﹤0.01% |
7,800
-5,100
| -40% | -$91K |
|
4771
PUT
Lifecore Biomedical
LFCR
$164M
| $123K | ﹤0.01% |
15,000
+3,500
| +30% | +$25.9K |
|
|
KZR
4772
CALL
DELISTED
Kezar Life Sciences
KZR
| $123K | ﹤0.01% |
+19,500
| New | +$114K |
|
4773
CALL
Rekor Systems
REKR
$84.6M
| $123K | ﹤0.01% |
88,800
-24,300
| -21% | -$49.6K |
|
4774
PUT
Agree Realty
ADC
$9.42B
| $122K | ﹤0.01% |
1,700
-1,400
| -45% | -$102K |
|
4775
PUT
nVent Electric
NVT
$23.4B
| $122K | ﹤0.01% |
1,200
-8,700
| -88% | -$903K |
|
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.