ACK Asset Management LLC

GREENWICH, CT · CIK 1510940 · 13F filing filed 2026-08-13

No investment adviser registration (Form ADV) found for this filer. It may be a parent company whose subsidiaries are the registered advisers, a bank or insurer, or a manager based outside the US.

Legal entityACK ASSET MANAGEMENT LLC (US)

$856.3m reported value +6.9% vs Q1 2026

21positions

60.2%in top 10

7 new 5 added 5 reduced 6 sold out vs Q1 2026

Holdings, Q2 2026

The small lines show how much was held over the last 4 quarters (adjusted for stock splits).

#	Security	Ticker	Shares	Value	% of portfolio	Change	Shares change
1	ADVANCED DRAIN SYS INC DEL COM WMS	WMS	390,000	$61.2m7.15%	7.15%	Unchanged
2	HELIOS TECHNOLOGIES INC COM HLIO	HLIO	681,000	$60.8m7.10%	7.10%	Reduced -99.4k	-99,378 -12.7%
3	LITTELFUSE INC COM LFUS	LFUS	125,000	$56.9m6.65%	6.65%	Reduced -10.0k	-10,000 -7.4%
4	JAMES HARDIE INDS PLC ORD SHS JHX	JHX	2,100,000	$55.0m6.42%	6.42%	Unchanged
5	GARRETT MOTION INC COM GTX	GTX	1,500,000	$54.3m6.35%	6.35%	New
6	CORE & MAIN INC CL A CNM	CNM	1,090,000	$52.6m6.14%	6.14%	Added +190.0k	+190,000 21.1%
7	EAGLE MATLS INC COM EXP	EXP	220,000	$49.5m5.78%	5.78%	Added +55.0k	+55,000 33.3%
8	ATS CORPORATION COM ATS	ATS	1,500,000	$43.2m5.04%	5.04%	Reduced -346.2k	-346,196 -18.8%
9	ASTEC INDS INC COM ASTE	ASTE	690,276	$42.2m4.93%	4.93%	Reduced -96.2k	-96,224 -12.2%
10	MATERION CORP COM MTRN	MTRN	135,000	$40.1m4.69%	4.69%	Reduced -339.8k	-339,800 -71.6%
11	BORGWARNER INC COM BWA	BWA	600,000	$39.8m4.65%	4.65%	New
12	DNOW INC COM DNOW	DNOW	3,000,000	$38.9m4.54%	4.54%	New
13	MASTERBRAND INC COMMON STOCK MBC	MBC	3,700,000	$38.1m4.45%	4.45%	Unchanged
14	SITEONE LANDSCAPE SUPPLY INC COM SITE	SITE	330,000	$37.8m4.41%	4.41%	Unchanged
15	LATHAM GROUP INC COM SWIM	SWIM	5,660,000	$36.6m4.28%	4.28%	Added +500.0k	+500,000 9.7%
16	CLEARFIELD INC COM CLFD	CLFD	810,200	$32.2m3.76%	3.76%	Added +75.0k	+75,000 10.2%
17	SENSATA TECHNOLOGIES HLDG PL SHS ST	ST	600,000	$28.6m3.34%	3.34%	New
18	AERO-SWX COM MTASF	MTASF	1,082,500	$28.5m3.32%	3.32%	Added +252.5k	+252,500 30.4%
19	SHOALS TECHNOLOGIES GROUP IN CL A SHLS	SHLS	2,255,000	$22.3m2.61%	2.61%	New
20	EQUIPMENTSHARE COM INC COM CL A EQPT	EQPT	1,064,830	$20.9m2.44%	2.44%	New
21	METHODE ELECTRS INC COM MEI	MEI	877,500	$16.6m1.94%	1.94%	New

Sold out since Q1 2026

Security	Ticker	Shares held before	Value then
ROGERS CORP ROG	ROG	475,000	$51.0m475.0k shares
NOVANTA INC NOVT	NOVT	375,000	$44.3m375.0k shares
DXP ENTERPRISES INC DXPE	DXPE	260,000	$36.3m260.0k shares
CARDINAL INFRASTRUCTURE GROU CDNL	CDNL	874,000	$34.7m874.0k shares
GRANITE CONSTR INC GVA	GVA	250,000	$30.0m250.0k shares
CTS CORP CTS	CTS	584,000	$27.9m584.0k shares

Stakes above 5%

Companies where this manager has reported owning more than 5% of a class of shares, on Schedule 13D (may seek influence) or 13G (passive): its latest filing for each, from 19 Dec 2024 on.

Company	Ticker	Stake	Change	Schedule	Last filed
CLEARFIELD INC CLFD · 13G · filed 2026-04-15	CLFD	5.1%≈ $28.3m	+0.2 pts	13G	2026-04-15