ACK Asset Management LLC is an SEC-registered investment adviser based in Greenwich, CT that reports managing 2 hedge funds on Form ADV. It reports $1.1 billion in regulatory assets under management. Its private funds, of all types, hold $1.1 billion in gross assets. Its disclosed U.S. stock holdings returned an estimated +42.7% 2026 YTD through Jun 30 (S&P 500: +9.5%), based on 13F filings. Over a longer period they returned an estimated +87.6% from Q3 2024 to Q2 2026, compared with +37.2% for the S&P 500, based on 13F filings.
- Regulatory assets under management
- $1.1 billionForm ADV Item 5.F
- Gross assets of private funds
- $1.1 billionAll private fund types, Form ADV
- Hedge funds managed
- 22 private funds in total
- Employees
- 10Form ADV Item 5.A
- Registration
- SEC-registered adviserCRD 155136
- Latest Form ADV
- 03/13/2026Disciplinary disclosures: none reported
Estimated 13F portfolio performance
| Quarter | Est. 13F return | S&P 500 |
|---|---|---|
| Q2 2026 | +33.9% | +14.8% |
| Q1 2026 | +6.5% | -4.6% |
| Q4 2025 | +3.7% | +2.4% |
| Q3 2025 | +12.4% | +7.8% |
| Q2 2025 | +26.4% | +10.4% |
| Q1 2025 | -11.7% | -4.5% |
| Q4 2024 | -0.5% | +2.1% |
| Q3 2024 | +1.4% | +5.4% |
Estimate of the firm's disclosed long U.S. stock portfolio from its quarterly 13F filings, holding each quarter-end portfolio to the next quarter-end at prices implied by all 13F filers. It is a price return before dividends and fees, ignores shorts, options, bonds, cash and trading within the quarter, and is not the return of any fund. Disclosures
Largest disclosed holdings
- Advanced Drainage Systems Inc$61.2 million
- Helios Technologies Inc$60.8 million
- Littelfuse Inc$56.9 million
- James Hardie Inds PLC$55.0 million
- Garrett Motion Inc$54.3 million
- Core & Main Inc CL A$52.6 million
- Eagle Materials Inc$49.5 million
- Ats Corporation$43.2 million
- Astec Inds Inc$42.2 million
- Materion Corp$40.1 million
As of 2026-06-30, from 13F filing by ACK Asset Management LLC.
From SEC filings. Firm data comes from the SEC's Form ADV data as of Oct 2, 2026; performance estimates come from Form 13F. HedgeMountain has not verified this information, and it is not an offer, solicitation or recommendation. Full disclosures