Algoma Steel Group Inc.
ASTL- Exchange
- Nasdaq
- Industry
- Steel Works, Blast Furnaces & Rolling Mills (Coke Ovens)
- SEC CIK
- 0001860805
No open-market purchases or sales by Algoma Steel Group Inc. insiders were filed in the last 90 days; 95 institutions reported holding it in 13F filings for Q2 2026, worth $291.8M in total; no superinvestor holds it.
Other share classesASTLW
Holders of 5% or more of ASTL
Holders whose latest Schedule 13D or 13G filing reports 5% or more of Algoma Steel Group Inc., largest stake first. The change is against the holder's previous filing.
| Holder | Latest form | Stake | Change | First filed | Latest filing | Filing |
|---|---|---|---|---|---|---|
| Maple Rock Capital Partners Inc. | 13G/A | 13.30%14.0M shares | +3.40 ppfrom 9.90% | May 5, 20254 filings | Nov 7, 2025 | SEC |
| MMCAP International Inc. SPC | 13G/A | 10.90%11.5M shares | +0.90 ppfrom 10.00% | May 15, 20255 filings | Feb 17, 2026 | SEC |
| Donald Smith & Co., Inc. | 13G | 5.60%5.86M shares | −0.10 ppfrom 5.70% | Feb 13, 20255 filings | Feb 12, 2026 | SEC |
| Stoney Lonesome HF LP | 13G/A | 5.40%5.86M shares | +0.20 ppfrom 5.20% | Apr 10, 20252 filings | Aug 14, 2025 | SEC |
Stakes are as of each holder's latest filing. Holders whose last filing was in the old format (before December 18, 2024) have no stake on record and are not listed, and after an acquisition or delisting holders usually stop filing.
13D and 13G filings
18 Schedule 13D and 13G filings on Algoma Steel Group Inc., newest first, including old-format filings without a stake.
| Filed (ET) | Filer | Form | Stake | Change | Event date | Filing |
|---|---|---|---|---|---|---|
| Feb 17, 20264:00 PM ET | MMCAP International Inc. SPCand 1 other | 13G/A | 10.90%11.5M shares | +0.90 ppfrom 10.00% | Dec 31, 2025 | SEC |
| Feb 12, 20269:21 AM ET | Donald Smith & Co., Inc.and 1 other | 13G | 5.60%5.86M shares | −0.10 ppfrom 5.70% | Dec 31, 2025 | SEC |
| Nov 20, 20252:57 PM ET | MMCAP International Inc. SPCand 1 other | 13G/A | 10.00%10.5M shares | +2.30 ppfrom 7.70% | Nov 18, 2025 | SEC |
| Nov 14, 20254:40 PM ET | MMCAP International Inc. SPCand 1 other | 13G/A | 7.70%8.08M shares | +0.80 ppfrom 6.90% | Sep 30, 2025 | SEC |
| Nov 12, 202511:59 AM ET | Donald Smith & Co., Inc.and 1 other | 13G | 5.70%5.94M shares | −0.10 ppfrom 5.80% | Sep 30, 2025 | SEC |
| Nov 7, 20254:12 PM ET | Maple Rock Capital Partners Inc.and 1 other | 13G/A | 13.30%14.0M shares | +3.40 ppfrom 9.90% | Oct 31, 2025 | SEC |
| Sep 23, 20254:15 PM ET | Zekelman Industries, Inc.and 1 other | 13D/A | 3.08%3.23M shares | –Below 5% | Sep 10, 2025 | SEC |
| Aug 28, 20256:57 PM ET | Maple Rock Capital Partners Inc.and 1 other | 13G | 9.90%10.4M shares | 0.00 ppfrom 9.90% | Aug 28, 2025 | SEC |
| Aug 14, 20258:48 PM ET | Maple Rock Capital Partners Inc.and 1 other | 13D/A | 9.90%10.4M shares | +2.70 ppfrom 7.20% | Aug 12, 2025 | SEC |
| Aug 14, 20254:32 PM ET | MMCAP International Inc. SPCand 1 other | 13G/A | 6.90%7.22M shares | +0.60 ppfrom 6.30% | Jun 30, 2025 | SEC |
| Aug 14, 20254:12 PM ET | Stoney Lonesome HF LPand 4 others | 13G/A | 5.40%5.86M shares | +0.20 ppfrom 5.20% | Jun 30, 2025 | SEC |
| Aug 13, 20252:57 PM ET | Donald Smith & Co., Inc.and 1 other | 13G | 5.80%6.04M shares | −1.90 ppfrom 7.70% | Jun 30, 2025 | SEC |
| May 15, 20254:47 PM ET | MMCAP International Inc. SPCand 1 other | 13G/A | 6.30%6.64M shares | – | Mar 31, 2025 | SEC |
| May 13, 20252:02 PM ET | Donald Smith & Co., Inc.and 1 other | 13G | 7.70%8.09M shares | −0.10 ppfrom 7.80% | Mar 31, 2025 | SEC |
| May 5, 20257:07 PM ET | Maple Rock Capital Partners Inc.and 1 other | 13D/A | 7.20%7.55M shares | – | May 1, 2025 | SEC |
| Apr 29, 20259:27 AM ET | BlackRock, Inc. | 13G/A | 3.70%3.84M shares | –Below 5% | Mar 31, 2025 | SEC |
| Apr 10, 20251:19 PM ET | Stoney Lonesome HF LPand 2 others | 13G | 5.20%5.46M shares | New | Apr 4, 2025 | SEC |
| Feb 13, 20252:13 PM ET | Donald Smith & Co., Inc.and 1 other | 13G | 7.80%8.07M shares | New | Dec 31, 2024 | SEC |
Form 144: proposed insider sales
Notices from officers, directors and other affiliates planning to sell Algoma Steel Group Inc. shares.
No Form 144 notices for Algoma Steel Group Inc. are on file.