Skip to main content
Livermore
Livermore
ZHEN

ACK Asset Management LLC

SEC CIK
0001510940
Latest filing
Aug 13, 2026

The latest 13F from ACK Asset Management LLC covers Q2 2026 (filed Aug 13, 2026): 21 long positions worth $856.3M. The top 10 holdings make up 60.2% of the portfolio, and the largest is Advanced Drainage Systems, Inc. (WMS) at 7.1%. Livermore has 23 filings on Form 13F from this institution, going back to Q1 2021.

What changed in Q2 2026

Share counts compared with Q1 2026: how many positions were new, added to, reduced or sold out, and the biggest buys and sells. Dollar amounts are estimated at the quarter-end prices implied by the filing.

Full comparison
New
7
Est. +$221.6M
Added
5
Est. +$34.4M
Reduced
5
Est. −$130.3M
Sold out
6
Est. −$224.1M

Top 5 holdings

Share of this quarter's portfolio value

  1. WMSAdvanced Drainage Systems, Inc.
    7.1%$61.2MHistory
  2. HLIOHelios Technologies, Inc.
    7.1%$60.8MHistory
  3. LFUSLittelfuse Inc
    6.6%$56.9MHistory
  4. JHXJames Hardie Industries plc
    6.4%$55.0MHistory
  5. GTXGarrett Motion Inc.
    6.3%$54.3MHistory

Biggest buys

New and added positions, by estimated amount bought

  1. GTXGarrett Motion Inc.
    +$54.3MNewHistory
  2. BWABorgwarner Inc
    +$39.8MNewHistory
  3. DNOWDNOW Inc.
    +$38.9MNewHistory
  4. STSensata Technologies Holding plc
    +$28.6MNewHistory
  5. SHLSShoals Technologies Group, Inc.
    +$22.3MNewHistory

Largest weight increases

New and added positions, by percentage points of the portfolio gained

  1. GTXGarrett Motion Inc.
    +6.35 pp0.0% → 6.3%History
  2. BWABorgwarner Inc
    +4.65 pp0.0% → 4.7%History
  3. DNOWDNOW Inc.
    +4.54 pp0.0% → 4.5%History
  4. STSensata Technologies Holding plc
    +3.34 pp0.0% → 3.3%History
  5. SHLSShoals Technologies Group, Inc.
    +2.61 pp0.0% → 2.6%History

Biggest sells

Reduced and sold-out positions, by estimated amount sold

  1. MTRNMATERION Corp
    −$101.1MReducedHistory
  2. ROGRogers Corp
    −$51.0MSold outHistory
  3. NOVTNovanta Inc
    −$44.3MSold outHistory
  4. DXPEDXP Enterprises Inc
    −$36.3MSold outHistory
  5. CDNLCardinal Infrastructure Group Inc.
    −$34.7MSold outHistory

Largest weight decreases

Reduced and sold-out positions, by percentage points of the portfolio lost

  1. ROGRogers Corp
    −6.36 pp6.4% → 0.0%History
  2. NOVTNovanta Inc
    −5.53 pp5.5% → 0.0%History
  3. DXPEDXP Enterprises Inc
    −4.53 pp4.5% → 0.0%History
  4. CDNLCardinal Infrastructure Group Inc.
    −4.33 pp4.3% → 0.0%History
  5. MTRNMATERION Corp
    −3.88 pp8.6% → 4.7%History

Metrics

13F metrics for Q2 2026, computed only from the numbers in the filings. Definitions below.

Portfolio value
$856.3M
+$55.2M (+6.9%) vs. prior quarter
Positions
21
+1 vs. prior quarter
Top 10 concentration
60.2%
Top 10 as share of value
Turnover
30.9%
Q2 2026, one quarter
Average holding period
4.8 quarters
Weighted by value

How these are calculated

  • Portfolio value: the market value of all long positions in the 13F, as reported at quarter end, excluding options.
  • Top 10 concentration: the combined value of the 10 largest positions as a share of portfolio value.
  • Turnover: the smaller of this quarter's estimated purchases and estimated sales, divided by the average of this and last quarter's portfolio value. Estimates multiply the change in shares by the quarter-end price implied by the filing (market value divided by shares); new positions use this quarter's value and sold-out positions last quarter's. Only positions reported in shares count, and it is not calculated when the previous quarter was not filed.
  • Average holding period: how many consecutive quarters each current position has been held (including this one; a quarter without the position or without a filing starts the count over), weighted by this quarter's value. Counting starts with the first 13F in Livermore (Q1 2021), so positions held before then are understated.

13F filings by quarter

22 quarters, going back to Q1 2021. Bars show each quarter's 13F portfolio value; quarters without a filing are left blank.

Peak $858.3M (Q1 2024)

Q1 2021: $251.4MQ2 2021: $271.7MQ3 2021: $341.6MQ4 2021: $423.9MQ1 2022: $461.0MQ2 2022: $357.3MQ3 2022: $377.5MQ4 2022: $544.6MQ1 2023: $655.1MQ2 2023: $802.9MQ3 2023: $688.2MQ4 2023: $831.3MQ1 2024: $858.3MQ2 2024: $810.3MQ3 2024: $809.2MQ4 2024: $746.4MQ1 2025: $609.0MQ2 2025: $761.4MQ3 2025: $799.1MQ4 2025: $796.8MQ1 2026: $801.1MQ2 2026: $856.3M
Q1 2021Q2 2026
13F filings of ACK Asset Management LLC by quarter
QuarterFiledPositionsValueTop 3 holdingsChangesFiling
Q2 2026Aug 13, 202621$856.3MWMSHLIOLFUSvs. Q1 2026SEC
Q1 2026May 15, 202620$801.1MMTRNWMSATSvs. Q4 2025SEC
Q4 2025Feb 13, 202623$796.8MMTRNGVAWMSvs. Q3 2025SEC
Q3 2025Nov 14, 202520$799.1MENSMTRNGVAvs. Q2 2025SEC
Q2 2025Aug 13, 202521$761.4MATROATSDYvs. Q1 2025SEC
Q1 2025May 13, 202520$609.0MDYENSMTZvs. Q4 2024SEC
Q4 2024Feb 13, 202522$746.4MDYMTZATSvs. Q3 2024SEC
Q3 2024Nov 13, 202418$809.2MDYMTZENSvs. Q2 2024SEC
Q2 2024Aug 13, 202419$810.3MDYMTZENSvs. Q1 2024SEC
Q1 2024May 14, 202420$858.3MCNMDYATKRvs. Q4 2023SEC
Q4 2023Feb 13, 202421$831.3MMTRNDYMTZvs. Q3 2023SEC
Q3 2023Nov 13, 202321$688.2MENSATKRATSvs. Q2 2023SEC
Q2 2023Aug 15, 2023Amended23$802.9MENSMTZROGvs. Q1 2023SEC
Q1 2023May 12, 202323$655.1MROGMTRNENSvs. Q4 2022SEC
Q4 2022Feb 14, 202325$544.6MMTRNEMEROGvs. Q3 2022SEC
Q3 2022Nov 14, 202223$377.5MEMEMTRNENSvs. Q2 2022SEC
Q2 2022Aug 15, 202221$357.3MMTRNVMIEMEvs. Q1 2022SEC
Q1 2022May 13, 202224$461.0MENSMTRNBLDRvs. Q4 2021SEC
Q4 2021Feb 14, 202227$423.9MENSMTRNRDNWvs. Q3 2021SEC
Q3 2021Nov 12, 202126$341.6MENSROGTGIvs. Q2 2021SEC
Q2 2021Jul 13, 202124$271.7MENSTGIROGvs. Q1 2021SEC
Q1 2021May 14, 202123$251.4MROGTGIDY–SEC

13D and 13G filings

Companies where ACK Asset Management LLC reports owning 5% or more on Schedule 13D or 13G, and its latest filings.

Current stakes of 5% or more

1 company, largest stake first.

Companies where ACK Asset Management LLC owns 5% or more
CompanyLatest formStakeChangeFirst filedLatest filingFiling
CLFDClearfield, Inc.13G5.10%710.2K shares+0.20 ppfrom 4.90%Feb 14, 20253 filingsApr 15, 2026SEC

Latest filings

7 filings on file made by ACK Asset Management LLC or listing it as a reporting person, newest first.

Schedule 13D and 13G filings by ACK Asset Management LLC
CompanyFiled (ET)FormStakeChangeEvent dateFiling
CLFDClearfield, Inc.Apr 15, 20261:07 PM ET13G5.10%710.2K shares+0.20 ppfrom 4.90%Feb 20, 2026SEC
ATROAstronics CorpNov 18, 20253:49 PM ET13G/A4.00%1.23M shares–Below 5%Sep 30, 2025SEC
CLFDClearfield, Inc.May 13, 20255:28 PM ET13G/A4.90%687.2K shares−0.14 ppfrom 5.04%Below 5%Mar 31, 2025SEC
CLFDClearfield, Inc.Feb 14, 202512:46 PM ET13G5.04%720.0K sharesNewDec 31, 2024SEC
ATROAstronics CorpDec 12, 202413GOld format–New–SEC
ALNTAllient IncFeb 17, 202313GOld format–New–SEC
LUNALuna Innovations IncFeb 14, 202213GOld format–New–SEC