Institutional Manager · CIK 0001510940
ACK Asset Management LLC
GREENWICH, CT · File #028-14060
Latest AUM
$796.8M
Positions
23
Top-10 Concentration
61.1%
Filings
9
Portfolio Value Over Time
2024-03
2024-06
2024-09
2024-12
2025-03
2025-06
2025-09
2025-12
Biggest QoQ Changes
Ranked by conviction flow (share change × current price) so mark-to-market moves don't dominate. Price effect column shows how much of the $ change was just the stock moving.
| Action | Issuer | Ticker / CUSIP | Δ Shares | Flow ($) | Price Effect |
|---|---|---|---|---|---|
| EXITED | JBTM | 477839104 | -350,546 | -$49.2M | $0 |
| NEW | NOVT | NOVTU | +375,000 | +$44.6M | $0 |
| REDUCE | ENS | ENS | -280,000 | -$41.1M | +$19.7M |
| NEW | ROG | ROG | +436,707 | +$40.0M | $0 |
| REDUCE | ATRO | ATROB | -632,531 | -$34.3M | +$10.6M |
| EXITED | CTRI | 155923105 | -1,375,000 | -$29.1M | $0 |
| NEW | DXPE | DXPE | +240,000 | +$26.3M | $0 |
| NEW | CDNL | CDNL | +844,591 | +$20.4M | $0 |
| EXITED | NPKI | 651718504 | -1,576,808 | -$17.8M | $0 |
| ADD | EXP | 26969P108 | +75,000 | +$15.5M | -$2.4M |
Sector Allocation
Filing History
- 13F HOLDINGS REPORTQ/E Dec 202523 pos · $796.8M
- 13F HOLDINGS REPORTQ/E Sep 202520 pos · $799.1M
- 13F HOLDINGS REPORTQ/E Jun 202521 pos · $761.4M
- 13F HOLDINGS REPORTQ/E Mar 202520 pos · $609.0M
- 13F HOLDINGS REPORTQ/E Dec 202422 pos · $746.4M
- 13F HOLDINGS REPORTQ/E Sep 202418 pos · $809.2M
- 13F HOLDINGS REPORTQ/E Jun 202419 pos · $810.3M
- 13F HOLDINGS REPORTQ/E Mar 202420 pos · $858.3M
- 13F HOLDINGS REPORTQ/E Dec 202321 pos · $688,243
Top 20 Holdings — Dec 2025
| # | Issuer | Ticker | Shares | Value | % of Portfolio |
|---|---|---|---|---|---|
| 1 | MTRN | MTRN | 474,800 | $59.0M | 7.41% |
| 2 | GVA | GVA | 500,000 | $57.7M | 7.24% |
| 3 | WMS | 00790R104 | 390,000 | $56.5M | 7.09% |
| 4 | ATS | ATS | 1,846,196 | $50.8M | 6.38% |
| 5 | CNM | CNM | 900,000 | $46.8M | 5.87% |
| 6 | ENS | ENS | 304,324 | $44.7M | 5.61% |
| 7 | NOVT | NOVTU | 375,000 | $44.6M | 5.60% |
| 8 | JHX | G4253H101 | 2,100,000 | $43.6M | 5.47% |
| 9 | HLIO | HLIO | 780,378 | $41.7M | 5.24% |
| 10 | SITE | SITE | 330,000 | $41.1M | 5.16% |
| 11 | ROG | ROG | 436,707 | $40.0M | 5.02% |
| 12 | EXP | 26969P108 | 165,000 | $34.1M | 4.28% |
| 13 | ASTE | 046224101 | 786,500 | $34.1M | 4.28% |
| 14 | ATRO | ATROB | 597,469 | $32.4M | 4.07% |
| 15 | AIN | 012348108 | 600,000 | $30.4M | 3.82% |
| 16 | APOG | APOG | 813,000 | $29.6M | 3.72% |
| 17 | DXPE | DXPE | 240,000 | $26.3M | 3.31% |
| 18 | MBC | MBC | 2,300,000 | $25.4M | 3.19% |
| 19 | CDNL | CDNL | 844,591 | $20.4M | 2.56% |
| 20 | CLFD | CLFD | 625,200 | $18.2M | 2.29% |