Quantum Si Inc Class A (QSI)
$1.46 -16.57% Close Oct 30, 2026 Live
Quantum Si stock today
Quantum Si closed at $1.46 on October 30, 2026, down 16.57% on the day. Over the past year it returned -28.1% with dividends reinvested, against +12.4% for the S&P 500. Its market value is $318 million.
$1.00$1.50$2.00
NovJan 2026MarMayJulSep
| Period | QSI | S&P 500 (SPY) |
|---|---|---|
| 1 month | +36.4% | -0.9% |
| 3 months | +102.8% | +2.1% |
| Year to date | +32.7% | +11.7% |
| 1 year | -28.1% | +12.4% |
| 3 years | +24.8% | +88.5% |
| 5 years | -81.9% | +76.0% |
Key statistics
- Market value
- $318M
- Price / sales
- 198.1
- 52-week range
- $0.70 to $2.15
- Next report
- Nov 5, 2026
About Quantum Si
Quantum Si Inc develops and manufactures mass spectrometry instruments.
Sector: Health Care
More on Quantum Si
- Financials: revenue, earnings and segmentsRevenue -20% in the year to Dec 2025
- Returns: what $1,000 became$1,000 five years ago is $181.14 today
No forecast, no recommendation. This page describes Quantum Si Inc Class A from published data; it is not advice to buy, sell or hold any security.
Figures as of the close on Oct 30, 2026 unless a row says otherwise. Prices are split adjusted; returns include dividends reinvested. Data may be delayed. See the disclaimer and how TrendArc works.