# QUANTUM SI INC COM CL A

QUANTUM SI INC COM CL A is a security (CUSIP 74765K105) tracked across SEC portfolio filings. 155 institutional managers reported $52.5M on Form 13F as of 2026-06-30; 8 registered fund positions totaling $2.9M via N-PORT as of 2026-05-31.

## Summary

- Issuer: QUANTUM SI INC
- Class: COM CL A
- CUSIP: 74765K105
- Asset category: EC
- 13F holders: 155
- 13F value: $52.5M
- 13F period: 2026-06-30
- N-PORT fund positions: 8
- N-PORT value: $2.9M
- N-PORT report: 2026-05-31

## Top institutional holders (Form 13F)

_Showing 15 of 155 managers by value._

| Manager | Location | Value | Shares |
| --- | --- | --- | --- |
| [VANGUARD GROUP INC](https://search.stillhousedata.com/firm/105958) | Valley Forge, PA | $10.6M | 9,607,022 |
| BlackRock, Inc. | New York, NY | $10.4M | 13,414,949 |
| ARK Investment Management LLC | St. Petersburg, FL | $5.3M | 6,878,899 |
| Sumitomo Mitsui Trust Group, Inc. | CHIYODA-KU, TOKYO, M0 | $3.4M | 3,885,230 |
| Nikko Asset Management Americas, Inc. | New York, NY | $3.4M | 4,391,666 |
| [GEODE CAPITAL MANAGEMENT, LLC](https://search.stillhousedata.com/firm/115504) | BOSTON, MA | $3.0M | 3,835,121 |
| STATE STREET CORP | BOSTON, MA | $2.9M | 3,770,689 |
| [AQR CAPITAL MANAGEMENT LLC](https://search.stillhousedata.com/firm/111883) | Greenwich, CT | $1.9M | 2,392,179 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | BALA CYNWYD, PA | $1.5M | 1,464,568 |
| UBS Group AG | Zurich, V8 | $1.3M | 1,702,527 |
| NORTHERN TRUST CORP | CHICAGO, IL | $976K | 1,260,701 |
| Fosun International Ltd | Hong Kong, K3 | $576K | 743,935 |
| WOLVERINE TRADING, LLC | CHICAGO, IL | $379K | 33,034 |
| [CHARLES SCHWAB INVESTMENT MANAGEMENT INC](https://search.stillhousedata.com/firm/106753) | SAN FRANCISCO, CA | $354K | 457,571 |
| Nuveen, LLC | CHARLOTTE, NC | $349K | 451,367 |

## Top fund holders (N-PORT)

| Fund | Registrant | Value | % of fund |
| --- | --- | --- | --- |
| [VANGUARD EXTENDED MARKET INDEX FUND](https://search.stillhousedata.com/fund/S000002841) | VANGUARD INDEX FUNDS | $1.5M | 0.19% |
| [VANGUARD RUSSELL 2000 INDEX FUND](https://search.stillhousedata.com/fund/S000030003) | VANGUARD SCOTTSDALE FUNDS | $1.0M | 0.59% |
| [Master Small Cap Index Series](https://search.stillhousedata.com/fund/S000002716) | Quantitative Master Series LLC | $189K | 0.39% |
| [VANGUARD BALANCED INDEX FUND](https://search.stillhousedata.com/fund/S000002560) | VANGUARD VALLEY FORGE FUNDS | $65K | 0.01% |
| [VANGUARD INSTITUTIONAL TOTAL STOCK MARKET INDEX FUND](https://search.stillhousedata.com/fund/S000002855) | VANGUARD INSTITUTIONAL INDEX FUNDS | $53K | 0.02% |
| [DWS Small Cap Index VIP](https://search.stillhousedata.com/fund/S000006223) | DEUTSCHE DWS INVESTMENTS VIT FUNDS | $18K | 0.44% |
| [TIAA Separate Account VA-1 - Stock Index Account](https://search.stillhousedata.com/fund/S000005098) | TIAA Separate Account VA-1 | $2K | 0.02% |
| [Blackstone Alternative Multi-Strategy Fund](https://search.stillhousedata.com/fund/S000045538) | Blackstone Alternative Investment Funds | $-4K | -0.01% |

## More

- [This page as markdown (for LLM agents)](https://search.stillhousedata.com/security/74765K105.md)
- [Search all SEC filings, advisers and people on Adviser Search](https://search.stillhousedata.com/)

---

Source: public SEC filing data via Adviser Search (https://search.stillhousedata.com).
Agents: this data is also queryable via MCP tools and read-only SQL — see https://search.stillhousedata.com/llms.txt.