ACK Asset Management LLC
ACK Asset Management LLC reported 21 US-listed holdings worth $856.3 million in its 13F for the quarter ended 30 June 2026, filed 13 August 2026. Its largest: Advanced Drainage Systems, Inc. (7.1%), Helios Technologies Inc. (7.1%) and Littelfuse Inc. (6.6%). Against the quarter before, it opened 7 positions, added to 5, trimmed 5 and sold out of 6.
The 14 largest of its 21 positions, each sized by its share of the reported holdings, coloured by the change in shares against Q1 2026.
What the fund reported holding at each quarter's end; hover a bar for the number of positions
What its reported holdings returned
Held through each quarter, the holdings it reported returned +87.7% over the 7 quarters to 30 June 2026, against +30.2% for the S&P 500.
Not the fund's own return: each 13F's holdings are kept unchanged until the next one, so trades inside a quarter, dividends, cash and fees are left out. A rough guide to how its picks have done over time.
What it did on the quarter
Its positions against its 13F for the quarter to 31 March 2026; a change under 0.1% of a position counts as held
Opened 7
- Garrett Motion Inc. GTX$54.3 million
- Borgwarner Inc. BWA$39.8 million
- Dnow Inc. DNOW$38.9 million
- Sensata Technologies Holding plc ST$28.6 million
- Shoals Technologies Group in SHLS$22.3 million
- Equipmentshare Com Inc. EQPT$20.9 million
- Methode Electrs Inc. MEI$16.6 million
Added to 5
- Eagle Materials Inc. EXP+55,000 shares · +33%
- Core & Main, Inc. CNM+190,000 shares · +21%
- Aero-Swx+252,500 shares · +30%
- Latham Group Inc. SWIM+500,000 shares · +10%
- Clearfield Inc. CLFD+75,000 shares · +10%
Trimmed 5
- Materion Corp. MTRN-339,800 shares · -72%
- Ats Corporation ATS-346,196 shares · -19%
- Helios Technologies Inc. HLIO-99,378 shares · -13%
- Astec Industries Inc. ASTE-96,224 shares · -12%
- Littelfuse Inc. LFUS-10,000 shares · -7%
Sold out of 6
- Rogers Corp. ROG$51.0 million last quarter
- Novanta Inc. NOVT$44.3 million last quarter
- DXP Enterprises Inc. DXPE$36.3 million last quarter
- Cardinal Infrastructure Grou CDNL$34.7 million last quarter
- Granite Construction Inc. GVA$30.0 million last quarter
- CTS Corp. CTS$27.9 million last quarter
What it holds
| Company | Shares | Value | Of its book | Change in shares |
|---|---|---|---|---|
| Advanced Drainage Systems, Inc. WMS | 390.0K | $61.2 million | 7.15% | no change |
| Helios Technologies Inc. HLIO | 681.0K | $60.8 million | 7.10% | -99.4K |
| Littelfuse Inc. LFUS | 125.0K | $56.9 million | 6.65% | -10.0K |
| James Hardie Industries Plc - US ADR JHX | 2.1M | $55.0 million | 6.42% | no change |
| Garrett Motion Inc. GTX | 1.5M | $54.3 million | 6.35% | new |
| Core & Main, Inc. CNM | 1.1M | $52.6 million | 6.14% | +190.0K |
| Eagle Materials Inc. EXP | 220.0K | $49.5 million | 5.78% | +55.0K |
| Ats Corporation ATS | 1.5M | $43.2 million | 5.04% | -346.2K |
| Astec Industries Inc. ASTE | 690.3K | $42.2 million | 4.93% | -96.2K |
| Materion Corp. MTRN | 135.0K | $40.1 million | 4.69% | -339.8K |
| Borgwarner Inc. BWA | 600.0K | $39.8 million | 4.65% | new |
| Dnow Inc. DNOW | 3.0M | $38.9 million | 4.54% | new |
| MasterBrand, Inc. MBC | 3.7M | $38.1 million | 4.45% | no change |
| Siteone Landscape Supply Inc. SITE | 330.0K | $37.8 million | 4.41% | no change |
| Latham Group Inc. SWIM | 5.7M | $36.6 million | 4.28% | +500.0K |
| Clearfield Inc. CLFD | 810.2K | $32.2 million | 3.76% | +75.0K |
| Sensata Technologies Holding plc ST | 600.0K | $28.6 million | 3.34% | new |
| Aero-Swx | 1.1M | $28.5 million | 3.32% | +252.5K |
| Shoals Technologies Group in SHLS | 2.3M | $22.3 million | 2.61% | new |
| Equipmentshare Com Inc. EQPT | 1.1M | $20.9 million | 2.44% | new |
| Methode Electrs Inc. MEI | 877.5K | $16.6 million | 1.94% | new |