ACK Asset Management LLC
In its 13F for Q3 2025 (holdings as of September 30, 2025, filed November 14, 2025), ACK Asset Management LLC reported 20 stock positions worth $799.1 million. Its top holding was Enersys (ENS) at 8.3% of the portfolio, followed by Materion (MTRN, 7.9%) and Granite Construction (GVA, 7.5%). Compared with Q2 2025, it opened 7 new positions, sold out of 8, added to 5 and reduced 2. The biggest buy was a new position in Core & Main Class A (CNM) and the biggest sale an exit from Dycom Industries (DY).
- Most Recent 13F
- Q2 2026
- Location
- GREENWICH, CT
- CIK
- 0001510940
- Portfolio Value
- $799.1M (Q3 2025)
- SEC Filing
- 0001510940-25-000006 ↗ filed Nov 14, 2025
Holdings Value
Holdings 20 stocks · $799.1M
| ENS Enersys | 8.26% | 584,324 | $66.0M | No change |
| MTRN Materion Corp. | 7.93% | 524,800 | $63.4M | No change |
| GVA Granite Construction Inc. | 7.48% | 545,000 | $59.8M | No change |
| ATRO Astronics Corp. | 7.02% | 1,230,000 | $56.1M | Reduce -40.3% |
| WMS Advanced Drainage Systems Inc. | 6.77% | 390,000 | $54.1M | Add +13.0% |
| JBTM JBT Marel Corp. | 6.16% | 350,546 | $49.2M | No change |
| CNM Core & Main Inc. Class A | 6.06% | 900,000 | $48.4M | New |
| ATS Ats Corp. | 6.05% | 1,846,196 | $48.4M | No change |
| AIN Albany Intl Corp. Class A | 5.07% | 760,000 | $40.5M | Add +29.9% |
| JHX James Hardie Ind PLC | 5.05% | 2,100,000 | $40.3M | New |
| HLIO Helios Technologies Inc. | 5.02% | 770,000 | $40.1M | New |
| SITE Siteone Landscape Supply Inc. | 4.51% | 280,000 | $36.1M | Add +12.0% |
| ASTE Astec Industries Inc. | 4.22% | 701,500 | $33.8M | New |
| APOG Apogee Enterprises Inc. | 3.86% | 708,000 | $30.8M | New |
| MBC Masterbrand Inc. | 3.79% | 2,300,000 | $30.3M | New |
| CTRI Centuri Holdings Inc. | 3.64% | 1,375,000 | $29.1M | Reduce -32.3% |
| CLFD Clearfield Inc. | 2.69% | 625,200 | $21.5M | No change |
| EXP Eagle Materials Inc. | 2.62% | 90,000 | $21.0M | New |
| NPKI NPK International Inc. | 2.23% | 1,576,808 | $17.8M | Add +28.5% |
| CTOS Custom Truck One Source Inc. | 1.55% | 1,925,000 | $12.4M | Add +2.7% |
Portfolio Sells Q2 2025 → Q3 2025
| DY Dycom Industries Inc. | Sold out | 0.00% | −7.21 |
| MYRG MYR Group Inc./Delaware | Sold out | 0.00% | −6.32 |
| RRX Regal Rexnord Corp. | Sold out | 0.00% | −5.24 |
| MRC MRC Global Inc. | Sold out | 0.00% | −4.08 |
| MIR Mirion Technologies Inc. | Sold out | 0.00% | −3.78 |
| MTZ Mastec Inc. | Sold out | 0.00% | −2.80 |
| CTRI Centuri Holdings Inc. | Reduce -32.3% | 3.64% | −2.35 |
| ATRO Astronics Corp. | Reduce -40.3% | 7.02% | −2.04 |
| MTRX Matrix Service Co. | Sold out | 0.00% | −1.93 |
| DXPE DXP Enterprises Inc. | Sold out | 0.00% | −0.87 |
Portfolio Buys Q2 2025 → Q3 2025
| CNM Core & Main Inc. Class A | New | 6.06% | +6.06 |
| JHX James Hardie Ind PLC | New | 5.05% | +5.05 |
| HLIO Helios Technologies Inc. | New | 5.02% | +5.02 |
| ASTE Astec Industries Inc. | New | 4.22% | +4.22 |
| APOG Apogee Enterprises Inc. | New | 3.86% | +3.86 |
| MBC Masterbrand Inc. | New | 3.79% | +3.79 |
| EXP Eagle Materials Inc. | New | 2.62% | +2.62 |
| WMS Advanced Drainage Systems Inc. | Add +13.0% | 6.77% | +1.56 |
| NPKI NPK International Inc. | Add +28.5% | 2.23% | +0.86 |
| SITE Siteone Landscape Supply Inc. | Add +12.0% | 4.51% | +0.54 |
| CTOS Custom Truck One Source Inc. | Add +2.7% | 1.55% | +0.33 |
| AIN Albany Intl Corp. Class A | Add +29.9% | 5.07% | −0.32 |
All Filings
| Quarter | Positions | 13F Reported Value | Top Holdings |
|---|---|---|---|
| Q2 2026 | 21 | $856.3M | WMS, HLIO, LFUS, JHX, GTX |
| Q1 2026 | 20 | $801.1M | MTRN, WMS, ATS, ROG, HLIO |
| Q4 2025 | 23 | $796.8M | MTRN, GVA, WMS, ATS, CNM |
| Q3 2025 | 20 | $799.1M | ENS, MTRN, GVA, ATRO, WMS |
| Q2 2025 | 21 | $761.4M | ATRO, ATS, DY, GVA, ENS |
| Q1 2025 | 20 | $609.0M | DY, ENS, MTZ, ATS, ATRO |
| Q4 2024 | 22 | $746.4M | DY, MTZ, ATS, ENS, ROG |
| Q3 2024 | 18 | $809.2M | DY, MTZ, ENS, ROG, ATS |
| Q2 2024 | 19 | $810.3M | DY, MTZ, ENS, ROG, CNM |
| Q1 2024 | 20 | $858.3M | CNM, DY, ATKR, MTZ, ENS |