ACK Asset Management LLC holds a focused book of 20 stocks worth $801.1M as of Q1 2026 (disclosed May 15, 2026, a ~45-day 13F lag). This quarter they opened Littelfuse Inc and trimmed Granite Construction Inc. Their largest long position is Materion Corp at 9% of the equity book. Cloning the disclosed picks since 2013 would be +369% (+12.9%/yr). That is a simulation of the disclosed long book, not audited returns.
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curl -H "Authorization: Bearer YOUR_API_KEY" \ "https://arkolith.com/api/v1/funds/1510940/holdings"
Use Arkolith to show ACK Asset Management LLC's latest holdings, largest changes, and filing provenance.
The reported book (valued from quarter-end) returned +483.5%, a 114.8-point gap that is the cost of the ~45-day 13F disclosure lag a real follower can't avoid.
Growth of $10,000 cloning ACK Asset Management LLC's disclosed long 13F book, rebalanced on each filing date (so it reflects the ~45-day reporting lag, no look-ahead), total-return basis (dividends reinvested), derived from end-of-day prices. “Their reported book” values the same picks from quarter-end, before they were public. S&P 500 is SPY total return over the same window. Excludes shorts, cash, options and non-13F holdings. Not investment advice.
Top-heavy: focused book
Share of the disclosed book in its largest positions. A higher top-5 share means a more concentrated, higher-conviction portfolio.
97% mapped to company sectors
Direct operating-company sectors from our SIC-based security master. ETF/fund and unclassified holdings stay visible separately; this is not ETF look-through exposure.
Estimated $ traded · quarter-end prices, no cost basis
Other tracked managers holding the same core names as ACK Asset Management LLC
| Manager / fund | Shared names | Their $ in those |
|---|---|---|
| BlackRock, Inc. | 25 / 20 | $8.4B |
| VANGUARD GROUP INC | 25 / 20 | $7.2B |
| VANGUARD CAPITAL MANAGEMENT LLC | 25 / 20 | $3.4B |
| FMR LLC | 25 / 20 | $2.7B |
| GEODE CAPITAL MANAGEMENT, LLC | 25 / 20 | $1.7B |
| MORGAN STANLEY | 25 / 20 | $1.2B |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 25 / 20 | $929.5M |
| JPMORGAN CHASE & CO | 25 / 20 | $779.4M |
Ranked by how many of ACK Asset Management LLC's top 20 disclosed names each fund also holds: a cross-fund conviction signal from the latest 13F of every tracked manager.
Bars show each stock's share of the portfolio. Click a row for its position history.
| # | Security | Value | Shares | % Port | Last move | History |
|---|---|---|---|---|---|---|
| 1 | MTRN COM | $68.7M | 474.8K | 8.6% | —Held | |
| 2 | WMS COM | $53.5M | 390.0K | 6.7% | —Held | |
| 3 | ATS COM | $52.1M | 1.85M | 6.5% | —Held | |
| 4 | ROG COM | $51.0M | 475.0K | 6.4% | ▲+8.8% Added · +38K sh | |
| 5 | HLIO COM | $50.5M | 780.4K | 6.3% | —Held | |
| 6 | LFUS COM | $45.8M | 135.0K | 5.7% | ▲New New position | |
| 7 | CNM COM | $44.5M | 900.0K | 5.5% | —Held | |
| 8 | NOVT COM | $44.3M | 375.0K | 5.5% | —Held | |
| 9 | SITE COM | $43.9M | 330.0K | 5.5% | —Held | |
| 10 | ASTE COM | $42.3M | 786.5K | 5.3% | —Held | |
| 11 | JHX COM | $39.8M | 2.10M | 5.0% | —Held | |
| 12 | DXPE COM | $36.3M | 260.0K | 4.5% | ▲+8.3% Added · +20K sh | |
| 13 | CDNL COM | $34.7M | 874.0K | 4.3% | ▲+3.5% Added · +29K sh | |
| 14 | EXP COM | $31.3M | 165.0K | 3.9% | —Held | |
| 15 | MBC COM | $30.7M | 3.70M | 3.8% | ▲+61% Added · +1.4M sh | |
| 16 | GVA COM | $30.0M | 250.0K | 3.7% | ▼−50% Reduced · −250K sh | |
| 17 | CTS COM | $27.9M | 584.0K | 3.5% | ▲New New position | |
| 18 | SWIM COM | $27.7M | 5.16M | 3.5% | ▲New New position | |
| 19 | Aero-SWX COM | $26.8M | 830.0K | 3.3% | ▲+436% Added · +675K sh | |
| 20 | CLFD COM | $19.5M | 735.2K | 2.4% | ▲+18% Added · +110K sh |
As-of date vs the date the SEC received each filing
| Quarter | As of | Filed | Positions | Value | Form |
|---|---|---|---|---|---|
| Q1 2026 | Mar 31, 2026 | May 15, 2026 | 20 | $801.1M | 13F-HR |
| Q4 2025 | Dec 31, 2025 | Feb 13, 2026 | 23 | $796.8M | 13F-HR |
| Q3 2025 | Sep 30, 2025 | Nov 14, 2025 | 20 | $799.1M | 13F-HR |
| Q2 2025 | Jun 30, 2025 | Aug 13, 2025 | 21 | $761.4M | 13F-HR |
| Q1 2025 | Mar 31, 2025 | May 13, 2025 | 20 | $609.0M | 13F-HR |
| Q4 2024 | Dec 31, 2024 | Feb 13, 2025 | 22 | $746.4M | 13F-HR |
| Q3 2024 | Sep 30, 2024 | Nov 13, 2024 | 18 | $809.2M | 13F-HR |
| Q2 2024 | Jun 30, 2024 | Aug 13, 2024 | 19 | $810.3M | 13F-HR |
| Q1 2024 | Mar 31, 2024 | May 14, 2024 | 20 | $858.3M | 13F-HR |
| Q4 2023 | Dec 31, 2023 | Feb 13, 2024 | 21 | $831.3M | 13F-HR |
| Q3 2023 | Sep 30, 2023 | Nov 13, 2023 | 21 | $688.2M | 13F-HR |
| Q2 2023 | Jun 30, 2023 | Aug 15, 2023 | 23 | $802.9M | 13F-HR/A |
| Q1 2023 | Mar 31, 2023 | May 12, 2023 | 23 | $655.1M | 13F-HR |
| Q4 2022 | Dec 31, 2022 | Feb 14, 2023 | 25 | $544.6M | 13F-HR |
| Q3 2022 | Sep 30, 2022 | Nov 14, 2022 | 23 | $377.5M | 13F-HR |
| Q2 2022 | Jun 30, 2022 | Aug 15, 2022 | 21 | $357.3M | 13F-HR |
| Q1 2022 | Mar 31, 2022 | May 13, 2022 | 24 | $461.0M | 13F-HR |
| Q4 2021 | Dec 31, 2021 | Feb 14, 2022 | 27 | $423.9M | 13F-HR |
| Q3 2021 | Sep 30, 2021 | Nov 12, 2021 | 26 | $341.6M | 13F-HR |
| Q2 2021 | Jun 30, 2021 | Jul 13, 2021 | 24 | $271.7M | 13F-HR |
| Q1 2021 | Mar 31, 2021 | May 14, 2021 | 23 | $251.4M | 13F-HR |
| Q4 2020 | Dec 31, 2020 | Feb 12, 2021 | 28 | $242.9M | 13F-HR |
| Q3 2020 | Sep 30, 2020 | Nov 13, 2020 | 19 | $194.6M | 13F-HR |
Holdings from SEC EDGAR 13F-HR filings, updated quarterly ~45 days after quarter-end. Public domain. The book and weighting are long equity only; disclosed put/call options are listed separately and excluded from those totals. The performance line is a simulation of the disclosed long book, not an audited return.