# QUANTUM SI INC (QSIAW)

> Institutional ownership reported to the SEC as of Q1 2026, from Form 13F filings. Source: https://holderbook.com/stocks/QSIAW/

- Reporting holders: 7
- Reported value: $59.5K
- Held through calls: 15.9%
- Held through puts: 0.0%

A 13F reports long US equity positions only. Shorts, bonds, foreign listings and cash are not visible here, and positions are disclosed up to 45 days after the quarter ends.

## Largest holders

| Manager | Value | Shares | Share of their book | Quarters held |
|---|---|---|---|---|
| [DEERFIELD MANAGEMENT COMPANY, L.P.](https://holderbook.com/funds/1009258-deerfield-management-company-l-p/) | $36.2K | 333,333 | 0.0% | 20 |
| [SUSQUEHANNA INTERNATIONAL GROUP, LLP](https://holderbook.com/funds/1446194-susquehanna-international-group-llp/) | $10.2K | 85,121 | 0.0% | 3 |
| [MILLENNIUM MANAGEMENT LLC](https://holderbook.com/funds/1273087-millennium-management-llc/) | $9.5K | 0 | 0.0% | 20 |
| [JANE STREET GROUP, LLC](https://holderbook.com/funds/1595888-jane-street-group-llc/) | $1.8K | 16,565 | 0.0% | 20 |
| [WOLVERINE ASSET MANAGEMENT LLC](https://holderbook.com/funds/1279891-wolverine-asset-management-llc/) | $1.6K | 14,522 | 0.0% | 1 |
| [UBS Group AG](https://holderbook.com/funds/1610520-ubs-group-ag/) | $227 | 2,080 | 0.0% | 3 |
| [TORONTO DOMINION BANK](https://holderbook.com/funds/947263-toronto-dominion-bank/) | $11 | 100 | 0.0% | 1 |

## Quarter by quarter

| Quarter | Holders | Reported value |
|---|---|---|
| Q1 2026 | 7 | $59.5K |
| Q4 2025 | 5 | $107.2K |
| Q3 2025 | 5 | $156.3K |
| Q2 2025 | 3 | $284.4K |
| Q1 2025 | 3 | $174.8K |
| Q4 2024 | 5 | $634.0K |
| Q3 2024 | 9 | $47.2K |
| Q2 2024 | 8 | $71.1K |
| Q1 2024 | 9 | $138.3K |
| Q4 2023 | 6 | $167.6K |
| Q3 2023 | 7 | $169.2K |
| Q2 2023 | 8 | $171.8K |