QUANTUM SI INC QSI
COM CL A · Common Stock · CUSIP 74765K105 · ISIN US74765K1051
- SectorTechnology
- IndustryMeasuring & Controlling Devices, NEC
- HeadquartersBranford, CT
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once ($6.9m this quarter). Holder counts are more reliable. Implied quarter-end price ≈ $1.20. Options: 9 managers hold calls ($1.5m notional), 11 hold puts ($1.9m).
Trends to Q1 2025
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q3 2022 | 102 |
| Q4 2022 | 106 |
| Q1 2023 | 101 |
| Q2 2023 | 92 |
| Q3 2023 | 97 |
| Q4 2023 | 92 |
| Q1 2024 | 96 |
| Q2 2024 | 101 |
| Q3 2024 | 108 |
| Q4 2024 | 122 |
| Q1 2025 | 138 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q2 2023 | 45 | 35 |
| Q3 2023 | 52 | 31 |
| Q4 2023 | 36 | 39 |
| Q1 2024 | 33 | 47 |
| Q2 2024 | 44 | 40 |
| Q3 2024 | 41 | 45 |
| Q4 2024 | 71 | 42 |
| Q1 2025 | 80 | 55 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q2 2024 | $536.0k | $17.6k | 0.03 |
| Q3 2024 | $307.8k | $16.4k | 0.05 |
| Q4 2024 | $5.7m | $2.2m | 0.38 |
| Q1 2025 | $1.5m | $1.9m | 1.28 |
Biggest buyers
| MILLENNIUM MANAGEMENT LLC | New | +3.9m |
| VANGUARD GROUP INC | Added | +1.4m |
| BlackRock, Inc. | Added | +1.0m |
| TWO SIGMA INVESTMENTS, LP | Added | +664.3k |
| GEODE CAPITAL MANAGEMENT, LLC | Added | +626.5k |
| RENAISSANCE TECHNOLOGIES LLC | Added | +326.8k |
| NORTHERN TRUST CORP | Added | +181.0k |
| CITADEL ADVISORS LLC | New | +138.5k |
| XTX Topco Ltd | Added | +123.4k |
| RAYMOND JAMES FINANCIAL INC | New | +92.9k |
Biggest sellers
| MORGAN STANLEY | Reduced | -3.2m |
| GOLDMAN SACHS GROUP INC | Reduced | -560.8k |
| SIMPLEX TRADING, LLC | Reduced | -263.9k |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Reduced | -205.9k |
| Amova Asset Management Americas, Inc. | Reduced | -153.8k |
| Sumitomo Mitsui Trust Group, Inc. | Reduced | -153.8k |
| Centiva Capital, LP | Sold out | -143.2k |
| UBS Group AG | Reduced | -142.4k |
| ARK Investment Management LLC | Reduced | -135.1k |
| GSA CAPITAL PARTNERS LLP | Reduced | -128.1k |
Biggest calls
| CITADEL ADVISORS LLC | Reduced | $357.4k297.8k shares |
| GROUP ONE TRADING LLC | Reduced | $314.8k262.3k shares |
| IMC-Chicago, LLC | New | $245.3k204.4k shares |
| SIMPLEX TRADING, LLC | Added | $230.0k192.4k shares |
| WOLVERINE TRADING, LLC | Added | $155.3k122.3k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Reduced | $119.6k99.7k shares |
| JANE STREET GROUP, LLC | Reduced | $44.8k37.3k shares |
| Callan Capital, LLC | Reduced | $9.0k40.0k shares |
| CONCOURSE FINANCIAL GROUP SECURITIES, INC. | Unchanged | $00 shares |
Biggest puts
| CITADEL ADVISORS LLC | Added | $626.0k521.7k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $448.6k373.8k shares |
| SIMPLEX TRADING, LLC | Added | $245.0k204.7k shares |
| IMC-Chicago, LLC | New | $233.2k194.3k shares |
| GROUP ONE TRADING LLC | Added | $118.0k98.3k shares |
| Sculptor Capital LP | New | $93.8k78.2k shares |
| WOLVERINE TRADING, LLC | Reduced | $56.6k44.6k shares |
| JANE STREET GROUP, LLC | Reduced | $44.9k37.4k shares |
| Jefferies Financial Group Inc. | New | $14.8k12.3k shares |
| NATIONAL BANK OF CANADA /FI/ | New | $13.3k111 shares |
Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.
Major shareholders (over 5%)
Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.
| Holder | Stake |
|---|---|
ROTHBERG JONATHAN M
13D · may seek influence
no change · filed 2026-08-28
Stated purposeIn connection with estate planning, entities owned by trusts created for the benefit of Dr. Jonathan Rothberg's children have entered into a trading plan pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934, as amended (the "Plan"), a copy of which is attached hereto as Exhibit 6. Pursuant to the Plan, sales of up to 8,947,746 shares of Class A common stock may be effected during the plan sales period beginning following the cooling-off period contained in Rule 10b5-1(c) on January 15, 2027 and ending on January 15, 2028 in accordance with the terms and conditions of the Plan. The sale of shares of Class A common stock under the Plan is subject to minimum price parameters included in the Plan, and there is no assurance that any shares of Class A common stock will be sold under… Full filing |
100.0% |
Fell to 5% or below in the last year: BlackRock, Inc. (2.3%, 2026-07-29)
Insider purchases and sales in Q1 2025
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
Officers and directors buying vs selling
Number of people, by quarter (10% owners not included)
Numbers
| Quarter | Buying | Bought | Selling | Sold | Sold under a plan |
|---|---|---|---|---|---|
| Q2 2023 | 0 | — | 0 | — | — |
| Q3 2023 | 0 | — | 0 | — | — |
| Q4 2023 | 0 | — | 0 | — | — |
| Q1 2024 | 3 | $141.9k | 0 | — | — |
| Q2 2024 | 0 | — | 1 | $9.1k | — |
| Q3 2024 | 4 | $234.8k | 1 | $4.1k | — |
| Q4 2024 | 0 | — | 2 | $11.7m | $11.7m |
| Q1 2025 | 0 | — | 4 | $57.7k | — |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2025-03-21 | Hawkins Jeffrey Alan President & CEO, director | Sold | $33.0k23.7k shares |
| 2025-03-21 | Keyes Jeffry R. Chief Financial Officer | Sold | $12.0k8.6k shares |
| 2025-03-21 | LaPointe Christian General Counsel & Corp. Secr. | Sold | $6.8k4.9k shares |
| 2025-03-21 | Vieceli John S. Chief Product Officer | Sold | $6.0k4.3k shares |
Their holding: how much the trade added to or took from the insider's holding (direct, or the trust or fund named). The same trade is sometimes reported by more than one insider, such as a fund and the director who represents it; totals count it once. A value is left blank where the reported price is far from the market price (usually a typo).
Holders, Q1 2025
| Manager | Shares | Change |
|---|---|---|
| BlackRock, Inc. 0.00% of their portfolio | 9.4m $11.3m | Added +1.0m |
| ARK Investment Management LLC 0.10% of their portfolio | 8.7m $10.5m | Reduced -135.1k |
| VANGUARD GROUP INC 0.00% of their portfolio | 6.9m $8.3m | Added +1.4m |
| Sumitomo Mitsui Trust Group, Inc. 0.00% of their portfolio | 5.8m $7.0m | Reduced -153.8k |
| Amova Asset Management Americas, Inc. 0.09% of their portfolio | 5.8m $6.9m | Reduced -153.8k |
| MILLENNIUM MANAGEMENT LLC 0.00% of their portfolio | 3.9m $4.7m | New |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 3.0m $3.6m | Added +626.5k |
| STATE STREET CORP 0.00% of their portfolio | 2.5m $2.9m | Added +49.1k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 1.0m $1.2m | Added +181.0k |
| RENAISSANCE TECHNOLOGIES LLC 0.00% of their portfolio | 871.8k $1.0m | Added +326.8k |
| TWO SIGMA INVESTMENTS, LP 0.00% of their portfolio | 817.0k $980.4k | Added +664.3k |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.00% of their portfolio | 796.9k $956.3k | Reduced -205.9k |
| Fosun International Ltd 0.25% of their portfolio | 743.9k $892.7k | Unchanged |
| UBS Group AG 0.00% of their portfolio | 449.7k $539.6k | Reduced -142.4k |
| GOLDMAN SACHS GROUP INC 0.00% of their portfolio | 441.3k $529.6k | Reduced -560.8k |
| XTX Topco Ltd 0.02% of their portfolio | 369.0k $442.8k | Added +123.4k |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 367.4k $440.9k | Added +59.4k |
| Nuveen, LLC 0.00% of their portfolio | 319.1k $382.9k | First filing |
| Knollwood Investment Advisory, LLC 0.04% of their portfolio | 300.0k $360.0k | Unchanged |
| Bank of New York Mellon Corp 0.00% of their portfolio | 294.9k $353.9k | Added +25.1k |
| MORGAN STANLEY 0.00% of their portfolio | 287.5k $345.0k | Reduced -3.2m |
| GSA CAPITAL PARTNERS LLP 0.03% of their portfolio | 246.2k $295.0k | Reduced -128.1k |
| Green Alpha Advisors, LLC 0.31% of their portfolio | 244.1k $292.9k | Added +85.2k |
| Pathstone Holdings, LLC 0.00% of their portfolio | 214.3k $257.2k | Added +85.7k |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC 0.01% of their portfolio | 196.1k $235.3k | Reduced -100.0k |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 150.0k $180.0k | Added +1.0k |
| CITADEL ADVISORS LLC 0.00% of their portfolio | 138.5k $166.2k | New |
| GUGGENHEIM CAPITAL LLC 0.00% of their portfolio | 129.0k $154.8k | Reduced -71.0k |
| Shay Capital LLC 0.04% of their portfolio | 128.5k $154.2k | Reduced -88.0k |
| BARCLAYS PLC 0.00% of their portfolio | 120.9k $145.1k | Reduced -29.7k |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 110.2k $132.2k | Added +34.1k |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 108.2k $130.0k | Reduced -940 |
| Invesco Ltd. 0.00% of their portfolio | 103.7k $124.4k | Added +66.3k |
| AQR CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 96.0k $115.3k | Reduced -6.4k |
| RAYMOND JAMES FINANCIAL INC 0.00% of their portfolio | 92.9k $111.5k | New |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 88.5k $106.2k | Reduced -23.4k |
| CITIGROUP INC 0.00% of their portfolio | 84.5k $101.4k | Reduced -5.8k |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 83.3k $100.0k | Added +11.4k |
| Jefferies Financial Group Inc. 0.00% of their portfolio | 83.0k $99.6k | New |
| FMR LLC 0.00% of their portfolio | 79.6k $95.5k | Reduced -698 |
| TWO SIGMA ADVISERS, LP 0.00% of their portfolio | 78.9k $94.7k | New |
| EWA, LLC 0.04% of their portfolio | 78.7k $94.4k | New |
| Sculptor Capital LP 0.00% of their portfolio | 78.2k $93.8k | New |
| MetLife Investment Management, LLC 0.00% of their portfolio | 76.0k $91.2k | New |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.00% of their portfolio | 70.6k $84.7k | Added +13.5k |
| IQ EQ FUND MANAGEMENT (IRELAND) Ltd 0.01% of their portfolio | 69.9k $83.9k | Added +36.0k |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 67.5k $81.0k | Added +35.0k |
| INTECH INVESTMENT MANAGEMENT LLC 0.00% of their portfolio | 61.4k $73.6k | Added +10.5k |
| Callan Capital, LLC 0.01% of their portfolio | 61.0k $73.1k | Added +50.1k |
| VOYA INVESTMENT MANAGEMENT LLC 0.00% of their portfolio | 59.1k $70.9k | Added +28.2k |
| Corebridge Financial, Inc. 0.00% of their portfolio | 58.9k $70.7k | Added +9.1k |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 57.7k $69.2k | Added +12.8k |
| TWO SIGMA SECURITIES, LLC 0.01% of their portfolio | 52.2k $62.7k | New |
| Mariner, LLC 0.00% of their portfolio | 48.0k $57.6k | Added +14.6k |
| SIMPLEX TRADING, LLC 0.00% of their portfolio | 42.9k $51.0k | Reduced -263.9k |
| COMMONWEALTH EQUITY SERVICES, LLC 0.00% of their portfolio | 40.9k $49.0k | Added +9.9k |
| WOLVERINE TRADING, LLC 0.00% of their portfolio | 40.5k $51.4k | Reduced -71.5k |
| SG Americas Securities, LLC 0.00% of their portfolio | 40.1k $48.0k | Reduced -27.5k |
| Cambridge Investment Research Advisors, Inc. 0.00% of their portfolio | 38.9k $47.0k | Unchanged |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE 0.00% of their portfolio | 38.5k $46.2k | Added +3.7k |
| Russell Investments Group, Ltd. 0.00% of their portfolio | 38.3k $45.9k | Added +29.2k |
| Red Wave Investments LLC 0.02% of their portfolio | 37.0k $44.4k | Unchanged |
| Sanctuary Advisors, LLC 0.00% of their portfolio | 36.8k $44.1k | Added +1.5k |
| Virtu Financial LLC 0.00% of their portfolio | 34.8k $42.0k | New |
| CAPTRUST FINANCIAL ADVISORS 0.00% of their portfolio | 34.6k $41.5k | New |
| SEI INVESTMENTS CO 0.00% of their portfolio | 33.1k $39.7k | Unchanged |
| Police & Firemen's Retirement System of New Jersey 0.00% of their portfolio | 31.1k $37.4k | Unchanged |
| Atom Investors LP 0.00% of their portfolio | 30.2k $36.2k | New |
| MERCER GLOBAL ADVISORS INC /ADV 0.00% of their portfolio | 27.1k $32.5k | Reduced -3.8k |
| Wealth Management Associates, Inc. 0.01% of their portfolio | 26.9k $32.3k | Reduced -8.1k |
| CIBC WORLD MARKETS CORP 0.00% of their portfolio | 26.7k $32.0k | New |
| NEW YORK STATE COMMON RETIREMENT FUND 0.00% of their portfolio | 26.1k $31.3k | Unchanged |
| ProShare Advisors LLC 0.00% of their portfolio | 26.0k $31.2k | Reduced -2.2k |
| Leonteq Securities AG 0.00% of their portfolio | 25.0k $30.1k | New |
| HBW ADVISORY SERVICES LLC 0.00% of their portfolio | 24.2k $29.1k | New |
| Vanguard Personalized Indexing Management, LLC 0.00% of their portfolio | 23.5k $28.2k | Added +3.5k |
| WestHill Financial Advisors, Inc. 0.01% of their portfolio | 21.7k $26.1k | New |
| Tower Research Capital LLC (TRC) 0.00% of their portfolio | 21.0k $25.2k | Reduced -2.3k |
| LPL Financial LLC 0.00% of their portfolio | 20.1k $24.1k | New |
| CIBC WORLD MARKET INC. 0.00% of their portfolio | 20.0k $24.0k | New |
| HOLLENCREST CAPITAL MANAGEMENT 0.00% of their portfolio | 20.0k $24.0k | New |
| Cetera Investment Advisers 0.00% of their portfolio | 19.1k $22.9k | Added +5.7k |
| DLK Investment Management, LLC 0.01% of their portfolio | 19.0k $22.8k | Unchanged |
| SBI Securities Co., Ltd. 0.00% of their portfolio | 19.0k $22.8k | Reduced -3.3k |
| Stratos Wealth Advisors, LLC 0.00% of their portfolio | 18.3k $22.0k | New |
| VICTORY CAPITAL MANAGEMENT INC 0.00% of their portfolio | 16.6k $19.9k | Added +4.5k |
| NEUBERGER BERMAN GROUP LLC 0.00% of their portfolio | 15.9k $19.1k | New |
| Kestra Advisory Services, LLC 0.00% of their portfolio | 15.1k $18.1k | New |
| MARK SHEPTOFF FINANCIAL PLANNING, LLC 0.01% of their portfolio | 14.5k $17.4k | Added +7.5k |
| Flagship Private Wealth, LLC 0.01% of their portfolio | 14.2k $17.0k | Unchanged |
| HSBC HOLDINGS PLC 0.00% of their portfolio | 14.0k $16.6k | Added +2.2k |
| Procyon Advisors, LLC 0.00% of their portfolio | 13.7k $16.4k | Unchanged |
| ROYAL BANK OF CANADA 0.00% of their portfolio | 13.4k $16.0k | Added +813 |
| STATE BOARD OF ADMINISTRATION OF FLORIDA RETIREMENT SYSTEM 0.00% of their portfolio | 12.3k $14.8k | New |
| Abel Hall, LLC 0.01% of their portfolio | 12.0k $14.4k | Added +1.6k |
| THOROUGHBRED FINANCIAL SERVICES, LLC 0.00% of their portfolio | 12.0k $14.0k | Reduced -21.0k |
| NATIONAL BANK OF CANADA /FI/ 0.00% of their portfolio | 11.1k $13.3k | New |
| Freedom Investment Management, Inc. 0.00% of their portfolio | 11.1k $13.3k | Reduced -5.4k |
| SIH Partners, LLLP 0.00% of their portfolio | 10.6k $12.7k | New |
| NewEdge Advisors, LLC 0.00% of their portfolio | 10.2k $12.3k | Unchanged |