William Harnisch Peconic Partners
William Harnisch is the founder of Peconic Partners, a concentrated investment firm known for high-conviction equity positions. The firm’s portfolio often differs sharply from broad market benchmarks, reflecting a willingness to concentrate capital. Harnisch’s disclosures are tracked by investors interested in bold, research-driven concentration.
Top Buys
| Rank | Stock | Value |
|---|---|---|
| 1 |
MasTec
MTZ
|
+$536M |
| 2 |
Amazon
AMZN
|
+$143M |
| 3 |
Freeport-McMoran
FCX
|
+$79.6M |
| 4 |
First Solar
FSLR
|
+$22.1M |
| 5 |
Dycom Industries
DY
|
+$1.88M |
Top Sells
| Rank | Stock | Value |
|---|---|---|
| 1 |
EQT Corp
EQT
|
+$31.1M |
| 2 |
Range Resources
RRC
|
+$28.2M |
| 3 |
Devon Energy
DVN
|
+$11M |
| 4 |
CTRA
Coterra Energy
CTRA
|
+$10.5M |
| 5 |
Antero Resources
AR
|
+$10.3M |
Sector Composition
| Rank | Sector | Weight |
|---|---|---|
| 1 | Industrials | 91.59% |
| 2 | Consumer Discretionary | 3.43% |
| 3 | Materials | 3.37% |
| 4 | Technology | 1.35% |
| 5 | Communication Services | 0.26% |
| Name | Market Value | Portfolio Weight | Shares or Principal |
Change in Stake | Capital Flow | |
|---|---|---|---|---|---|---|
1
Quanta Services
PWR
$96.1B
| $2.75B | 47.56% |
5,007,840
| – | – |
|
|
2
Dycom Industries
DY
$11.8B
| $1.39B | 24.11% |
4,113,320
+5,000
| +0.1% | +$1.88M |
|
|
3
MasTec
MTZ
$21.4B
| $1.15B | 19.92% |
3,578,431
+1,978,431
| +124% | +$536M |
|
|
4
Amazon
AMZN
$2.79T
| $199M | 3.44% |
953,414
+649,434
| +214% | +$143M |
|
|
5
Freeport-McMoran
FCX
$110B
| $195M | 3.37% |
3,317,068
+1,317,068
| +66% | +$79.6M |
|
|
6
First Solar
FSLR
$23B
| $77.9M | 1.35% |
395,000
+100,000
| +34% | +$22.1M |
|
7
Cinemark Holdings
CNK
$4.24B
| $11.4M | 0.2% |
400,000
| – | – |
|
8
AMC Entertainment Holdings
AMC
$2.28B
| $2.94M | 0.05% |
3,000,000
| – | – |
|
9
Alphabet (Google) Class A
GOOGL
$4.22T
| $518K | 0.01% |
1,800
| – | – |
|
|
10
Antero Resources
AR
$11.7B
| – | – |
-300,000
| Closed | -$10.3M |
|
|
CTRA
11
DELISTED
Coterra Energy
CTRA
| – | – |
-400,000
| Closed | -$10.5M |
|
|
12
Devon Energy
DVN
$54B
| – | – |
-300,000
| Closed | -$11M |
|
|
13
EQT Corp
EQT
$33.6B
| – | – |
-580,000
| Closed | -$31.1M |
|
|
14
Range Resources
RRC
$9.59B
| – | – |
-800,000
| Closed | -$28.2M |
|
15
Silicon Laboratories
SLAB
$7.27B
| – | – |
-30,000
| Closed | -$3.92M |
|
Similar funds
William Harnisch's Q1 2026 Portfolio in Review
As of Q1 2026, William Harnisch held 15 positions worth $5.78B, up 37% from $4.21B the previous quarter. Its ten largest holdings account for 100% of the portfolio.
William Harnisch deployed $687M of net new capital in Q1 2026, adding to 5 existing holdings.
By sector, the portfolio is most concentrated in Industrials at 92% of assets, up from 91% a quarter earlier, followed by Consumer Discretionary and Materials.
On the sell side, the most notable exit was EQT Corp, an estimated $31.1M sold.
- William Harnisch added most to MasTec in Q1 2026, an estimated $536M increase.
- William Harnisch fully exited EQT Corp in Q1 2026, selling an estimated $31.1M.
- William Harnisch's ten largest holdings make up 100% of its $5.78B portfolio in Q1 2026.
- William Harnisch opened 0 new positions and closed 6 in Q1 2026.
- William Harnisch's portfolio value rose 37% quarter-over-quarter to $5.78B.
Based on Peconic Partners's 13F filing for Q1 2026, filed 15 May 2026.