CIK: 0001510940
Total reported value
$801.1M
Reporting period: 2026-03-31 · Number of holdings: 20
ACK Asset Management LLC disclosed 20 holdings in its latest 13F filing for the period ending 2026-03-31, with total reported value of $801.1M and a quarterly turnover rate of 48.3%.
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ACK Asset Management LLC's disclosed holdings carry a Herfindahl concentration index of 0.054 — mathematically equivalent to about 18 equally-sized positions, close to its 20 actual disclosed holdings. Value is spread relatively evenly across the portfolio rather than concentrated in a handful of names.
Position sizes are fairly uniform across the portfolio (a coefficient of variation of 0.30), suggesting a disciplined, rules-based approach to how much capital goes into each idea.
No strong tilt toward either adding to existing winners or initiating outsized new positions was observed in the latest reported quarter.
Sector classification currently covers about 35% of this portfolio's disclosed value; the remainder includes holdings (e.g. unmapped tickers, options, or other security types) not yet covered by our sector mapping.
Trim GVA
-50.0% -$27.7M
Add H55555108
+436.0% $21.3M
Add CDNL
+3.5% $14.2M
Add ROG
+8.8% $11.0M
Add DXPE
+8.3% $10.0M
Add MTRN
0.0% $9.7M
| # | Ticker | Issuer | Asset Subclass | Weight | Weight Change | Shares Change | 4Q Trend |
|---|---|---|---|---|---|---|---|
| 1 | MTRN | Materion CORP | Stock-Other | 8.57% | +1.16% | — | |
| 2 | WMS | Advanced Drainage Systems In | Stock-Industrials | 6.68% | -0.41% | — | |
| 3 | ATS | Ats CORP | Stock-Other | 6.50% | +0.12% | — | |
| 4 | ROG | Rogers CORP | Stock-Other | 6.36% | +1.34% | +8.77% | |
| 5 | HLIO | Helios Technologies INC | Stock-Other | 6.30% | +1.06% | — | |
| 6 | LFUS | Littelfuse INC | Stock-Tech | 5.72% | +5.72% | NEW | |
| 7 | CNM | Core & Main Inc-class A | Stock-Industrials | 5.55% | -0.32% | — | |
| 8 | NOVT | Novanta INC | Stock-Other | 5.53% | -0.07% | — | |
| 9 | SITE | Siteone Landscape Supply INC | Stock-Industrials | 5.48% | +0.32% | — | |
| 10 | ASTE | Astec Industries INC | Stock-Other | 5.29% | +1.01% | — | |
| 11 | JHX | James Hardie Industries plc | Stock-Other | 4.96% | -0.51% | — | |
| 12 | DXPE | Dxp Enterprises INC | Stock-Other | 4.53% | +1.22% | +8.33% | |
| 13 | CDNL | Cardinal Infrastructure Gr-a | Stock-Other | 4.33% | +1.77% | +3.48% | |
| 14 | EXP | Eagle Materials INC | Stock-Materials | 3.90% | -0.38% | — | |
| 15 | MBC | Masterbrand INC | Stock-Consumer Disc | 3.84% | +0.65% | +60.87% | |
| 16 | GVA | Granite Construction INC | Stock-Industrials | 3.74% | -3.50% | -50.00% | |
| 17 | CTS | Cts CORP | Stock-Other | 3.48% | +3.48% | NEW | |
| 18 | SWIM | Latham Group INC | Stock-Other | 3.46% | +3.46% | NEW | |
| 19 | ✓ | Stock-Other | 3.35% | +2.66% | +436.00% | ||
| 20 | CLFD | Clearfield INC | Stock-Other | 2.43% | +0.14% | +17.59% |
Performance for Q3 2026
+3.7%
Performance Last 4 Quarters
+45.3%
Based on 77% of reported portfolio value with available pricing
| Period | Holdings | Total value | Stability | Top holdings |
|---|---|---|---|---|
| 2026-03-31 | 20 | $801.1M | 48 | |
| 2025-12-31 | 23 | $796.8M | 44 | |
| 2025-09-30 | 20 | $799.1M | 98 | |
| 2025-06-30 | 21 | $761.4M | 0 | |
| 2025-03-31 | 20 | $609.0M | 100 | |
| 2024-12-31 | 22 | $746.4M | 0 | |
| 2024-09-30 | 18 | $809.2M | 0 | |
| 2024-06-30 | 19 | $810.3M | 0 | |
| 2024-03-31 | 20 | $858.3M | 0 | |
| 2023-12-31 | 21 | $831.3M | 0 | |
| 2023-09-30 | 21 | $688.2M | 0 | |
| 2023-06-30 | 23 | $802.9M | 0 | |
| 2023-03-31 | 23 | $655.1M | 0 | |
| 2022-12-31 | 25 | $544.6M | 0 | |
| 2022-09-30 | 23 | $377.5M | 0 | |
| 2022-06-30 | 21 | $357.3M | 0 | |
| 2022-03-31 | 24 | $461.0M | 0 | |
| 2021-12-31 | 27 | $423.9M | 0 | |
| 2021-09-30 | 26 | $341.6M | 0 | |
| 2021-06-30 | 24 | $271.7M | 96 | |
| 2021-03-31 | 23 | $251.4M | 53 | |
| 2020-12-31 | 28 | $242.9M | 68 | |
| 2020-09-30 | 19 | $194.6M | 38 | |
| 2020-06-30 | 20 | $220.6M | 52 | |
| 2020-03-31 | 20 | $200.2M | 93 | |
| 2019-12-31 | 23 | $344.6M | 100 | |
| 2019-09-30 | 374 | $503.0M | 100 | |
| 2019-06-30 | 26 | $344.3M | 99 | |
| 2019-03-31 | 30 | $361.7M | 77 | |
| 2018-12-31 | 29 | $294.9M | 63 | |
| 2018-09-30 | 26 | $364.0M | 48 | |
| 2018-06-30 | 32 | $374.5M | 54 | |
| 2018-03-31 | 29 | $397.6M | 60 | |
| 2017-12-31 | 32 | $445.4M | 76 | |
| 2017-09-30 | 30 | $362.2M | 68 | |
| 2017-06-30 | 33 | $443.2M | 54 | |
| 2017-03-31 | 27 | $337.4M | 86 | |
| 2016-12-31 | 30 | $340.0M | 78 | |
| 2016-09-30 | 31 | $329.9M | 62 | |
| 2016-06-30 | 27 | $336.5M | 64 | |
| 2016-03-31 | 26 | $254.1M | 85 | |
| 2015-12-31 | 23 | $195.1M | 89 | |
| 2015-09-30 | 22 | $238.9M | 79 | |
| 2015-06-30 | 32 | $357.7M | 61 | |
| 2015-03-31 | 35 | $316.6M | 90 | |
| 2014-12-31 | 35 | $277.4M | 52 | |
| 2014-09-30 | 29 | $278.4M | 57 | |
| 2014-06-30 | 31 | $332.7M | 45 | |
| 2014-03-31 | 31 | $303.7M | 75 | |
| 2013-12-31 | 34 | $303.2M | 78 | |
| 2013-09-30 | 31 | $260.0M | 100 | |
| 2013-06-30 | 40 | $246.7M | 0 |
ACK Asset Management LLC's most significant position changes for 2026-03-31: New buy: Littelfuse INC (LFUS); Sold out: Enersys (ENS); Sold out: Astronics CORP (ATRO); Sold out: Albany Intl Corp-cl A (AIN); Sold out: Apogee Enterprises INC (APOG).
| # | Ticker | Issuer | Weight Change | Shares Change | Action |
|---|---|---|---|---|---|
| 1 | ✓ | +2.7% | +436.00% | Add | |
| 2 | CDNL | Cardinal Infrastructure Gr-a | +1.8% | +3.48% | Add |
| 3 | ROG | Rogers CORP | +1.3% | +8.77% | Add |
| 4 | DXPE | Dxp Enterprises INC | +1.2% | +8.33% | Add |
| 5 | MTRN | Materion CORP | +1.2% | — | Unchanged |
| 6 | HLIO | Helios Technologies INC | +1.1% | — | Unchanged |
| 7 | ASTE | Astec Industries INC | +1% | — | Unchanged |
| 8 | MBC | Masterbrand INC | +0.7% | +60.87% | Add |
| 9 | SITE | Siteone Landscape Supply INC | +0.3% | — | Unchanged |
| 10 | CLFD | Clearfield INC | +0.1% | +17.59% | Add |
| 11 | ATS | Ats CORP | +0.1% | — | Unchanged |
| 12 | NOVT | Novanta INC | -0.1% | — | Unchanged |
| 13 | CNM | Core & Main Inc-class A | -0.3% | — | Unchanged |
| 14 | EXP | Eagle Materials INC | -0.4% | — | Unchanged |
| 15 | WMS | Advanced Drainage Systems In | -0.4% | — | Unchanged |
| 16 | JHX | James Hardie Industries plc | -0.5% | — | Unchanged |
| 17 | GVA | Granite Construction INC | -3.5% | -50.00% | Trim |
| 18 | LFUS | Littelfuse INC | — | NEW | New buy |
| 19 | ENS | Enersys | — | EXIT | Sold out |
| 20 | ATRO | Astronics CORP | — | EXIT | Sold out |
| 21 | AIN | Albany Intl Corp-cl A | — | EXIT | Sold out |
| 22 | APOG | Apogee Enterprises INC | — | EXIT | Sold out |
| 23 | CTS | Cts CORP | — | NEW | New buy |
| 24 | SWIM | Latham Group INC | — | NEW | New buy |
| 25 | ERII | Energy Recovery INC | — | EXIT | Sold out |
| 26 | CTOS | Custom Truck One Source INC | — | EXIT | Sold out |
| Period | Filed | Type | EDGAR |
|---|---|---|---|
| 2026-03-31 | 2026-05-15 | 13F-HR | View on EDGAR |
| 2025-12-31 | 2026-02-13 | 13F-HR | View on EDGAR |
| 2025-09-30 | 2025-11-14 | 13F-HR | View on EDGAR |
| 2025-06-30 | 2025-08-13 | 13F-HR | View on EDGAR |
| 2025-03-31 | 2025-05-13 | 13F-HR | View on EDGAR |
| 2024-12-31 | 2025-02-13 | 13F-HR | View on EDGAR |
| 2024-09-30 | 2024-11-13 | 13F-HR | View on EDGAR |
| 2024-06-30 | 2024-08-13 | 13F-HR | View on EDGAR |
| 2024-03-31 | 2024-05-14 | 13F-HR | View on EDGAR |
| 2023-12-31 | 2024-02-13 | 13F-HR | View on EDGAR |
| 2023-09-30 | 2023-11-13 | 13F-HR | View on EDGAR |
| 2023-06-30 | 2023-08-15 | Amendment | View on EDGAR |
| 2023-06-30 | 2023-08-14 | 13F-HR | View on EDGAR |
| 2023-03-31 | 2023-05-12 | 13F-HR | View on EDGAR |
| 2022-12-31 | 2023-02-14 | 13F-HR | View on EDGAR |
| 2022-09-30 | 2022-11-14 | 13F-HR | View on EDGAR |
| 2022-06-30 | 2022-08-15 | 13F-HR | View on EDGAR |
| 2022-03-31 | 2022-05-13 | 13F-HR | View on EDGAR |
| 2021-12-31 | 2022-02-14 | 13F-HR | View on EDGAR |
| 2021-09-30 | 2021-11-12 | 13F-HR | View on EDGAR |
| 2021-06-30 | 2021-07-13 | 13F-HR | View on EDGAR |
| 2021-03-31 | 2021-05-14 | 13F-HR | View on EDGAR |
| 2020-12-31 | 2021-02-12 | 13F-HR | View on EDGAR |
| 2020-09-30 | 2020-11-13 | 13F-HR | View on EDGAR |
| 2020-06-30 | 2020-08-13 | 13F-HR | View on EDGAR |
| 2020-03-31 | 2020-05-14 | 13F-HR | View on EDGAR |
| 2019-12-31 | 2020-02-12 | 13F-HR | View on EDGAR |
| 2019-09-30 | 2019-11-13 | Amendment | View on EDGAR |
| 2019-09-30 | 2019-11-13 | 13F-HR | View on EDGAR |
| 2019-06-30 | 2019-08-14 | 13F-HR | View on EDGAR |
| 2019-03-31 | 2019-05-13 | 13F-HR | View on EDGAR |
| 2018-12-31 | 2019-02-12 | 13F-HR | View on EDGAR |
| 2018-09-30 | 2018-11-09 | 13F-HR | View on EDGAR |
| 2018-06-30 | 2018-08-13 | 13F-HR | View on EDGAR |
| 2018-03-31 | 2018-05-14 | 13F-HR | View on EDGAR |
| 2017-12-31 | 2018-02-12 | 13F-HR | View on EDGAR |
| 2017-09-30 | 2017-11-13 | 13F-HR | View on EDGAR |
| 2017-06-30 | 2017-08-14 | 13F-HR | View on EDGAR |
| 2017-03-31 | 2017-05-12 | 13F-HR | View on EDGAR |
| 2016-12-31 | 2017-02-13 | 13F-HR | View on EDGAR |
| 2016-09-30 | 2016-11-10 | 13F-HR | View on EDGAR |
| 2016-06-30 | 2016-08-15 | 13F-HR | View on EDGAR |
| 2016-03-31 | 2016-05-16 | 13F-HR | View on EDGAR |
| 2015-12-31 | 2016-02-11 | 13F-HR | View on EDGAR |
| 2015-09-30 | 2015-11-16 | 13F-HR | View on EDGAR |
| 2015-06-30 | 2015-08-11 | 13F-HR | View on EDGAR |
| 2015-03-31 | 2015-05-14 | 13F-HR | View on EDGAR |
| 2014-12-31 | 2015-02-12 | 13F-HR | View on EDGAR |
| 2014-09-30 | 2014-11-14 | 13F-HR | View on EDGAR |
| 2014-06-30 | 2014-08-04 | 13F-HR | View on EDGAR |
| 2014-03-31 | 2014-05-09 | 13F-HR | View on EDGAR |
| 2013-12-31 | 2014-02-11 | 13F-HR | View on EDGAR |
| 2013-09-30 | 2013-11-13 | 13F-HR | View on EDGAR |
| 2013-06-30 | 2013-08-13 | 13F-HR | View on EDGAR |
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