Avalanche Treasury Corp (MASI) ownership: Top institutional holder: BlackRock, Inc. ($826.13M). Insider activity: Net Seller (0 buys, 20 sells). 5 recent congressional STOCK Act disclosures. SEC EDGAR first-party data.
| Holder | Shares | Market Value | Reported |
|---|---|---|---|
| BlackRock, Inc. | 4644578.00 | $826.13M | 2026-03-31 |
| Politan Capital Management LP | 4589648.00 | $816.36M | 2026-03-31 |
| VANGUARD GROUP INC | 4348786.00 | $565.60M | 2025-12-31 |
| Pentwater Capital Management LP | 3176000.00 | $564.92M | 2026-03-31 |
| BARCLAYS PLC | 2743985.00 | $488.07M | 2026-03-31 |
| HBK INVESTMENTS L P | 2576109.00 | $458.21M | 2026-03-31 |
| MASSACHUSETTS FINANCIAL SERVICES CO /MA/ | 2342790.00 | $416.69M | 2026-03-31 |
| VANGUARD CAPITAL MANAGEMENT LLC | 2050045.00 | $364.64M | 2026-03-31 |
| Insider | Transaction | Value | Date |
|---|---|---|---|
| Sell | null | 2026-06-10 | |
| Sell | null | 2026-06-10 | |
| Sell | null | 2026-06-10 | |
| Sell | null | 2026-06-10 | |
| Sell | null | 2026-06-10 | |
| Sell | null | 2026-06-10 | |
| Sell | null | 2026-06-10 | |
| Sell | null | 2026-06-10 |
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Institutional data from SEC Form 13F. Insider data from SEC Form 4. Congressional data from STOCK Act disclosures. Not personalized investment advice.