QUANTUM SI INC (QSI)
Institutional ownership reported to the SEC as of Q2 2026, across 21 quarters.
136
Reporting holders
$48.9M
Reported value
4.6%
Held as options
-14
Holder change
Options share is the part of reported value carried in derivative lines rather than shares. A high figure means institutions are expressing a view on this security without owning much of it.
Holders
| Filer | Value | Shares | Their book | Held | Change |
|---|---|---|---|---|---|
| VANGUARD CAPITAL MANAGEMENT LLC | $6.7M | 7,578,208 | 0.00% | 2q | +7.9%+$492.3K |
| ARK Investment Management LLC | $6.3M | 7,167,738 | 0.04% | 21q | +4.2%+$255.6K |
| BlackRock, Inc. | $4.6M | 5,225,352 | 0.00% | 8q | -61.0%-$7.2M |
| Amova Asset Management Americas, Inc. | $3.5M | 3,885,230 | 0.04% | 21q | -11.5%-$450.7K |
| Sumitomo Mitsui Trust Group, Inc. | $3.4M | 3,885,230 | 0.00% | 17q | -11.5%-$448.2K |
| MILLENNIUM MANAGEMENT LLC | $2.8M | 3,131,726 | 0.00% | new | NEW |
| UBS Group AG | $2.3M | 2,561,897 | 0.00% | 21q | +50.5%+$760.5K |
| JANE STREET GROUP, LLC | $2.1M | 2,142,735 | 0.00% | 14q | HELD |
| AQR CAPITAL MANAGEMENT LLC | $2.1M | 2,348,665 | 0.00% | 8q | -1.8%-$38.5K |
| GEODE CAPITAL MANAGEMENT, LLC | $2.0M | 2,236,526 | 0.00% | 21q | -41.7%-$1.4M |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | $1.4M | 1,116,750 | 0.00% | 21q | -23.7%-$424.4K |
| VANGUARD FIDUCIARY TRUST CO | $988.3K | 1,116,683 | 0.00% | 2q | HELD |
| STATE STREET CORP | $788.3K | 890,741 | 0.00% | 20q | -76.4%-$2.5M |
| GROUP ONE TRADING LLC | $700.3K | 107,473 | 0.00% | 21q | -62.2%-$1.2M |
| IMC-Chicago, LLC | $663.5K | 285,758 | 0.00% | 2q | +29.4%+$150.7K |
| Fosun International Ltd | $658.4K | 743,935 | 0.15% | 21q | HELD |
| RENAISSANCE TECHNOLOGIES LLC | $490.2K | 553,871 | 0.00% | 2q | +369.8%+$385.8K |
| SIMPLEX TRADING, LLC | $484.5K | 165,293 | 0.00% | 21q | +82.6%+$219.2K |
| VANGUARD PORTFOLIO MANAGEMENT LLC | $439.9K | 497,098 | 0.00% | 2q | -67.3%-$905.8K |
| GOLDMAN SACHS GROUP INC | $421.5K | 476,288 | 0.00% | 21q | +7.2%+$28.4K |
| NORTHERN TRUST CORP | $398.7K | 450,531 | 0.00% | 20q | -64.3%-$717.0K |
| Invesco Ltd. | $392.9K | 443,929 | 0.00% | 17q | +9.2%+$33.0K |
| BNP PARIBAS FINANCIAL MARKETS | $352.8K | 398,598 | 0.00% | 7q | +938.3%+$318.8K |
| IEQ CAPITAL, LLC | $310.5K | 350,816 | 0.00% | 2q | -1.9%-$6.1K |
| Aster Capital Management (DIFC) Ltd | $304.9K | 344,510 | 0.03% | new | NEW |
| CITADEL ADVISORS LLC | $294.6K | 44,335 | 0.00% | 21q | +185.2%+$191.3K |
| MORGAN STANLEY | $286.3K | 323,482 | 0.00% | 21q | +148.9%+$171.3K |
| IQ EQ FUND MANAGEMENT (IRELAND) Ltd | $284.2K | 321,134 | 0.02% | 9q | +9.9%+$25.7K |
| Knollwood Investment Advisory, LLC | $265.5K | 300,000 | 0.02% | 14q | HELD |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC | $182.4K | 206,100 | 0.00% | 14q | -21.1%-$48.7K |
| BARCLAYS PLC | $182.0K | 205,690 | 0.00% | 18q | +425.6%+$147.4K |
| XTX Topco Ltd | $157.2K | 177,680 | 0.00% | 9q | -54.4%-$187.2K |
| Verdence Capital Advisors LLC | $140.1K | 158,305 | 0.01% | 4q | -22.3%-$40.3K |
| Mariner, LLC | $139.6K | 157,689 | 0.00% | 8q | -21.0%-$37.2K |
| MERCER GLOBAL ADVISORS INC /ADV | $136.7K | 154,454 | 0.00% | 2q | +179.8%+$87.8K |
| Shay Capital LLC | $133.6K | 150,922 | 0.01% | 13q | HELD |
| FMR LLC | $109.5K | 123,767 | 0.00% | 16q | +287.2%+$81.2K |
| JONES FINANCIAL COMPANIES LLLP | $85.8K | 100,483 | 0.00% | 6q | -8.6%-$8.0K |
| AlphaCore Capital LLC | $83.2K | 89,493 | 0.00% | 5q | -30.3%-$36.2K |
| Cerity Partners LLC | $75.5K | 85,347 | 0.00% | 2q | +5.8%+$4.2K |
| Vanguard Global Advisers, LLC | $75.0K | 84,757 | 0.00% | 2q | HELD |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC | $74.9K | 84,612 | 0.00% | 20q | -81.5%-$330.1K |
| Sixth Street Partners Management Company, L.P. | $74.9K | 84,612 | 0.00% | new | NEW |
| Y-Intercept (Hong Kong) Ltd | $70.0K | 79,089 | 0.00% | new | NEW |
| RHUMBLINE ADVISERS | $67.2K | 75,989 | 0.00% | 17q | -60.6%-$103.6K |
| WINTON GROUP Ltd | $67.1K | 75,800 | 0.00% | new | NEW |
| CAPTRUST FINANCIAL ADVISORS | $64.7K | 73,128 | 0.00% | 6q | +5.9%+$3.6K |
| HOLLENCREST CAPITAL MANAGEMENT | $57.5K | 65,011 | 0.00% | 6q | +62.1%+$22.0K |
| BANK OF AMERICA CORP /DE/ | $52.7K | 59,585 | 0.00% | 21q | -63.2%-$90.6K |
| Creative Planning | $49.5K | 55,884 | 0.00% | 2q | +6.3%+$3.0K |
| Atom Investors LP | $45.6K | 51,554 | 0.00% | new | NEW |
| WEALTH ENHANCEMENT ADVISORY SERVICES, LLC | $45.2K | 63,435 | 0.00% | 2q | -29.2%-$18.6K |
| Merit Financial Group, LLC | $41.8K | 47,232 | 0.00% | 2q | +29.9%+$9.6K |
| Green Alpha Advisors, LLC | $40.6K | 45,921 | 0.03% | 12q | +6.3%+$2.4K |
| Sanctuary Advisors, LLC | $36.6K | 41,397 | 0.00% | 7q | -3.3%-$1.3K |
| Stratos Wealth Advisors, LLC | $35.4K | 40,036 | 0.00% | 6q | +166.3%+$22.1K |
| Point72 Asset Management, L.P. | $34.6K | 39,133 | 0.00% | new | NEW |
| BRIGHTON JONES LLC | $34.1K | 38,585 | 0.00% | 2q | +40.0%+$9.8K |
| Corient Private Wealth LP | $33.8K | 38,240 | 0.00% | new | NEW |
| Red Wave Investments LLC | $32.7K | 37,000 | 0.01% | 20q | HELD |
| Arax Advisory Partners | $32.6K | 36,790 | 0.00% | 2q | +2597.2%+$31.4K |
| SBI Securities Co., Ltd. | $29.2K | 33,009 | 0.00% | 7q | +2.7% |
| China Universal Asset Management Co., Ltd. | $27.9K | 31,484 | 0.00% | 3q | -9.3%-$2.8K |
| Kovack Advisors, Inc. | $27.4K | 31,000 | 0.00% | 3q | +3.3% |
| IPG Investment Advisors LLC | $27.3K | 30,864 | 0.00% | new | NEW |
| Nuveen, LLC | $26.6K | 30,077 | 0.00% | 6q | -93.3%-$372.9K |
| Northern Lights Advisors, Inc. | $26.5K | 29,989 | 0.01% | 3q | HELD |
| COMMONWEALTH EQUITY SERVICES, LLC | $24.0K | 27,100 | 0.00% | 12q | -9.0%-$2.4K |
| Wealth Management Associates, Inc. | $23.3K | 26,350 | 0.01% | 15q | -2.2% |
| Tower Research Capital LLC (TRC) | $21.0K | 23,758 | 0.00% | 19q | -4.8%-$1.0K |
| Pallas Capital Advisors LLC | $20.6K | 23,320 | 0.00% | 2q | -9.5%-$2.2K |
| DLK Investment Management, LLC | $19.9K | 19,000 | 0.01% | 2q | +13.4%+$2.4K |
| Leonteq Securities AG | $19.9K | 22,500 | 0.00% | 6q | -10.0%-$2.2K |
| HBW ADVISORY SERVICES LLC | $19.7K | 22,292 | 0.00% | 6q | -1.8% |
| NEUBERGER BERMAN GROUP LLC | $19.3K | 21,766 | 0.00% | new | NEW |
| LPL Financial LLC | $18.6K | 20,985 | 0.00% | 6q | -6.6%-$1.3K |
| Vanguard Personalized Indexing Management, LLC | $18.0K | 20,350 | 0.00% | 8q | -15.2%-$3.2K |
| Capital Investment Advisory Services, LLC | $17.7K | 20,000 | 0.00% | 6q | HELD |
| VICTORY CAPITAL MANAGEMENT INC | $17.4K | 19,630 | 0.00% | 16q | -0.9% |
| ANCHYRA PARTNERS LLC | $16.8K | 18,974 | 0.00% | new | NEW |
| Bank of New York Mellon Corp | $16.6K | 18,805 | 0.00% | 20q | -95.1%-$322.4K |
| Focus Partners Wealth | $15.2K | 17,219 | 0.00% | 2q | -26.8%-$5.6K |
| JPMORGAN CHASE & CO | $15.2K | 17,071 | 0.00% | 19q | -79.6%-$59.1K |
| Flagship Private Wealth, LLC | $12.5K | 14,158 | 0.00% | 17q | HELD |
| Procyon Advisors, LLC | $12.1K | 13,671 | 0.00% | 20q | HELD |
| Balyasny Asset Management L.P. | $12.1K | 13,629 | 0.00% | new | NEW |
| RAYMOND JAMES FINANCIAL INC | $11.5K | 13,008 | 0.00% | new | NEW |
| Laurion Capital Management LP | $11.3K | 12,749 | 0.00% | new | NEW |
| NorthCrest Asset Manangement, LLC | $10.8K | 11,218 | 0.00% | 2q | -7.6% |
| Callan Family Office, LLC | $10.7K | 12,119 | 0.00% | new | NEW |
| Jefferies Financial Group Inc. | $10.0K | 11,350 | 0.00% | new | NEW |
| Integrated Wealth Concepts LLC | $10.0K | 11,333 | 0.00% | 2q | -21.8%-$2.8K |
| NewEdge Advisors, LLC | $9.9K | 11,168 | 0.00% | 15q | -29.4%-$4.1K |
| Abel Hall, LLC | $9.8K | 11,060 | 0.00% | new | NEW |
| Krilogy Financial LLC | $9.4K | 10,635 | 0.00% | 2q | -36.4%-$5.4K |
| Schonfeld Strategic Advisors LLC | $9.2K | 10,439 | 0.00% | new | NEW |
| Cresset Asset Management, LLC | $9.0K | 10,207 | 0.00% | 3q | HELD |
| Apollon Wealth Management, LLC | $8.9K | 10,056 | 0.00% | new | NEW |
| KESTRA PRIVATE WEALTH SERVICES, LLC | $8.8K | 10,000 | 0.00% | 2q | HELD |
| Verde Capital Management | $8.8K | 10,000 | 0.00% | new | NEW |
Five percent filings
Anyone crossing 5% of a company must say so within days - far sooner than the next quarterly holdings report. A 13D declares an intent to influence the company; a 13G is the passive version. See all activist filings →
| Filed | Form | Filer | % of class |
|---|---|---|---|
| 2026-07-29 | 13G/A | BlackRock, Inc. | 2.3% |
Quarter by quarter
Coverage begins with the quarter ending 2018-12-31. Earlier filings exist only as occasional late amendments, too sparse to describe a market, so they are not shown.
| Quarter | Holders | Value | Shares | New | Added | Trimmed | Options |
|---|---|---|---|---|---|---|---|
| Q2 2026 | 136 | $48.9M | 52,747,732 | 27 | 34 | 54 | 4.6% |
| Q1 2026 | 150 | $50.4M | 62,913,646 | 38 | 37 | 35 | 3.2% |
| Q4 2025 | 129 | $77.5M | 66,942,176 | 27 | 32 | 36 | 4.9% |
| Q3 2025 | 117 | $97.1M | 64,340,847 | 13 | 38 | 34 | 6.4% |
| Q2 2025 | 126 | $130.9M | 64,186,889 | 15 | 50 | 32 | 3.9% |
| Q1 2025 | 129 | $71.5M | 57,222,970 | 38 | 39 | 29 | 4.0% |
| Q4 2024 | 115 | $149.5M | 52,697,807 | 30 | 36 | 22 | 4.8% |
| Q3 2024 | 100 | $45.8M | 51,672,015 | 16 | 21 | 28 | 0.6% |
| Q2 2024 | 92 | $56.1M | 53,127,212 | 11 | 26 | 25 | 0.8% |
| Q1 2024 | 90 | $105.5M | 53,087,377 | 13 | 17 | 32 | 1.1% |
| Q4 2023 | 82 | $114.4M | 56,439,631 | 3 | 24 | 22 | 0.9% |
| Q3 2023 | 90 | $91.9M | 54,146,946 | 21 | 29 | 15 | 2.2% |
| Q2 2023 | 83 | $77.7M | 43,312,109 | 9 | 32 | 15 | 0.3% |
| Q1 2023 | 83 | $74.6M | 42,306,273 | 11 | 21 | 25 | 0.3% |
| Q4 2022 | 84 | $83.2M | 45,037,365 | 7 | 28 | 15 | 0.9% |
| Q3 2022 | 103 | $133.3M | 47,618,772 | 10 | 27 | 23 | 1.8% |
| Q2 2022 | 104 | $142.2M | 48,649,261 | 32 | 25 | 22 | 1.8% |
| Q1 2022 | 95 | $220.8M | 45,922,916 | 18 | 31 | 21 | 2.6% |
| Q4 2021 | 98 | $382.3M | 47,235,118 | 34 | 20 | 14 | 2.8% |
| Q3 2021 | 75 | $382.1M | 44,629,718 | 25 | 17 | 12 | 2.5% |
| Q2 2021 | 74 | $551.2M | 44,421,135 | 78 | 0 | 0 | 3.0% |