Quantum-Si - Class A (QSI) closed at $1.40 on October 23, 2026, up 21.7% from the previous close, on volume of 11,177,547 shares (30-day average 8,038,291).
Data as of October 23, 2026.
Globe Newswire (Fri, 16-Oct 8:00 AM ET)
Quantum-Si Regains Compliance with Nasdaq Minimum Bid Price Requirement
Globe Newswire (Thu, 15-Oct 9:00 AM ET)
Quantum-Si Shares Jump After Proteus Program Reaches 19-Amino-Acid Detection Milestone
Market Chameleon (Fri, 9-Oct 6:27 AM ET)
Quantum-Si Demonstrates Detection of 19 Amino Acids in Proteus Development Program
Globe Newswire (Thu, 8-Oct 4:05 PM ET)
Globe Newswire (Mon, 28-Sep 8:15 PM ET)
Quantum-Si Announces Detection of 18 Amino Acids Using a Developmental Sequencing Kit on Proteus
Globe Newswire (Tue, 15-Sep 7:00 AM ET)
Quantum-Si Expands Proteus Roadshow with Additional U.S. and European Cities
Globe Newswire (Wed, 9-Sep 8:00 AM ET)
Quantum-Si to Participate in the H.C. Wainwright 28th Annual Global Investment Conference
Globe Newswire (Tue, 18-Aug 8:00 AM ET)
Quantum-Si Reports Second Quarter 2026 Financial Results and Provides Proteus Development Update
Globe Newswire (Thu, 13-Aug 4:05 PM ET)
Quantum-Si to Report Second Quarter 2026 Financial Results on August 13, 2026
Globe Newswire (Mon, 27-Jul 4:05 PM ET)
Quantum-Si Inc is a life sciences company focused on proteomics research and analytical technologies. It develops single-molecule detection platforms designed to enable next-generation protein sequencing (NGPS) and large-scale protein analysis. Its technology supports massively parallel sequencing of proteins and can also be applied to the study of nucleic acids, providing tools for researchers and clinical applications in molecular analysis. The company's revenue is derived from sales of products and services.
Quantum-Si - Class A trades on the NASDAQ stock market under the symbol QSI.
As of October 26, 2026, QSI stock price climbed to $1.43 with 6,785,078 million shares trading.
QSI has a beta of 3.40, meaning it tends to be more sensitive to market movements. QSI has a correlation of 0.15 to the broad based SPY ETF.
QSI has a market cap of $313.00 million. This is considered a Small Cap stock.
Last quarter Quantum-Si - Class A reported $344,000 in Revenue and -$.11 earnings per share. This beat revenue expectation by $36,400 and met earnings estimates .
In the last 3 years, QSI traded as high as $5.77 and as low as $.61.
The top ETF exchange traded funds that QSI belongs to (by Net Assets): ARKG, VTI, VXF, IBB, ITOT.
QSI has underperformed the market in the last year with a price return of -35.0% while the SPY ETF gained +15.1%. However, in the short term, QSI had mixed performance relative to the market. It has outperformed in the last 3 months, returning +81.0% vs +4.0% return in SPY. But in the last 2 weeks, QSI shares have been beat by the market, returning -6.5% compared to an SPY return of -1.6%.
QSI support price is $1.27 and resistance is $1.53 (based on 1 day standard deviation move). This means that using the most recent 20 day stock volatility and applying a one standard deviation move around the stock's closing price, stastically there is a 67% probability that QSI shares will trade within this expected range on the day.
