Quantum-Si Incorporated - Class A (QSI)
QSI moved a median of -0.48% 30 minutes after news, and 0.00% by the close. How QSI actually reacts to news — the realized, point-in-time move the market made, measured across 322 labeled events over the last three years with zero look-ahead.
QSI’s median reaction, across the day.
| Horizon | Median | % positive | Events |
|---|---|---|---|
| 5-min | 0.00% | 46% | 322 |
| 30-min | -0.48% | 45% | 322 |
| 60-min | -0.46% | 44% | 322 |
| to close | 0.00% | 45% | 320 |
| Middle 50% of QSI reactions | -2.25% to +1.78% |
|---|---|
| Median reaction (30-min) | -0.48% |
| Measured reactions | 322 |
Half of all Quantum-Si Incorporated - Class A news events land between -2.25% and +1.78% at 30 minutes.
Reaction stats as of 2026-09-21. Newest measured event . Reaction = percent move vs. the price at the news timestamp.
Email me when QSI moves on news.
One email per qualifying move — the headline, the measured reaction, and how it compares to QSI's baseline. Nothing else.
Recent QSI events, each with its measured reaction.
| Date | Headline | Event | Source | 5-min | To close |
|---|---|---|---|---|---|
| Quantum-Si to Provide a Business Update and Report Third Quarter 2026 Financial Results on November 5, 2026 | Press release | GlobeNewswire | -1.88% | -15.79% | |
| Form 8-K Quantum-Si Inc For: Oct 14 | SEC filing · Form 8-K | SEC EDGAR | +0.74% | -2.96% | |
| Quantum-Si Regains Compliance with Nasdaq Minimum Bid Price Requirement | Press release | GlobeNewswire | +0.74% | -2.96% | |
| Form 8-K Quantum-Si Inc For: Oct 08 | SEC filing · Form 8-K | SEC EDGAR | +5.52% | +21.43% | |
| Quantum-Si Demonstrates Detection of 19 Amino Acids in Proteus™ Development Program | Press release | GlobeNewswire | +5.52% | +21.43% | |
| Form 8-K Quantum-Si Inc For: Sep 28 | SEC filing · Form 8-K | SEC EDGAR | +3.23% | +19.02% | |
| Quantum-Si Presents Interim Proteus™ Data at World HUPO 2026 Demonstrating a Significant Step Change in Performance Compared to Platinum® Pro | Press release | GlobeNewswire | +3.23% | +19.02% | |
| Quantum-Si Announces Detection of 18 Amino Acids Using a Developmental Sequencing Kit on Proteus™ | Press release | GlobeNewswire | +2.64% | +0.00% | |
| Quantum-Si Expands Proteus™ Roadshow with Additional U.S. and European Cities | Press release | GlobeNewswire | +1.09% | -1.34% | |
| Quantum-Si to Participate in the H.C. Wainwright 28th Annual Global Investment Conference | Press release | GlobeNewswire | +0.81% | -0.61% | |
| Form 10-Q Quantum-Si Inc For: Jun 30 | SEC filing · Form 10-Q | SEC EDGAR | +2.25% | -1.36% | |
| Form 8-K Quantum-Si Inc For: Aug 13 | SEC filing · Form 8-K | SEC EDGAR | +2.25% | -1.36% | |
| Quantum-Si Reports Second Quarter 2026 Financial Results and Provides Proteus™ Development Update | Press release | GlobeNewswire | +2.25% | -1.36% | |
| Quantum-Si to Report Second Quarter 2026 Financial Results on August 13, 2026 | Press release | GlobeNewswire | -1.38% | -1.86% | |
| Form 8-K Quantum-Si Inc For: Jul 23 | SEC filing · Form 8-K | SEC EDGAR | +0.08% | -0.63% | |
| Form 8-K Quantum-Si Inc For: Jun 18 | SEC filing · Form 8-K | SEC EDGAR | +2.28% | +0.86% | |
| Quantum-Si Announces Inducement Grants Under Nasdaq Listing Rule 5635(c)(4) | Press release | Business Wire | -0.09% | -2.65% | |
| Quantum-Si and Cell Signaling Technology Partner to Advance Post-Translational Modification Analysis on Proteus™ | Press release | Business Wire | +1.74% | -2.93% | |
| Quantum-Si Announces the Expansion of the Proteus™ Roadshow | Press release | Business Wire | -0.25% | -2.46% | |
| Form SD Quantum-Si Inc | SEC filing · Form SD | SEC EDGAR | -2.77% | +0.00% | |
| Form 8-K Quantum-Si Inc For: May 15 | SEC filing · Form 8-K | SEC EDGAR | -1.07% | -4.64% | |
| Quantum-Si Announces Inducement Grants Under Nasdaq Listing Rule 5635(c)(4) | Press release | Business Wire | +0.12% | -0.04% | |
| Form 10-Q Quantum-Si Inc For: Mar 31 | SEC filing · Form 10-Q | SEC EDGAR | -2.46% | -4.57% | |
| Form 8-K Quantum-Si Inc For: May 07 | SEC filing · Form 8-K | SEC EDGAR | -2.46% | -4.57% | |
| Quantum-Si Reports First Quarter 2026 Financial Results and Highlights Proteus™ Development Milestones | Press release | Business Wire | -2.46% | -4.57% | |
| Quantum-Si to Participate in the H.C. Wainwright 4th Annual BioConnect Investor Conference at NASDAQ | Press release | Business Wire | -0.83% | -2.32% | |
| Quantum-Si Announces Successful Sequencing on Integrated Proteus™ Instruments | Press release | Business Wire | +1.11% | +2.47% | |
| Quantum-Si to Report First Quarter 2026 Financial Results on May 7, 2026 | Press release | Business Wire | -6.48% | -3.70% | |
| Quantum-Si Announces Two Customer Posters to be Presented at the American Association of Cancer Research Annual Meeting | Press release | Business Wire | +0.68% | +16.67% | |
| Quantum-Si Announces New Manuscript Demonstrating the Value of Single-molecule Protein Sequencing to Aid in Identifying New Cancer Treatment Strategies | Press release | Business Wire | +3.75% | +5.10% | |
| Quantum-Si Announces Inducement Grants Under Nasdaq Listing Rule 5635(c)(4) | Press release | Business Wire | -1.80% | +6.58% | |
| Quantum-Si Announces First Customer Samples Tested on the Proteus™ Prototype System | Press release | Business Wire | -2.91% | -3.16% | |
| Quantum-Si Announces the Start of the Proteus™ Roadshow | Press release | Business Wire | -2.13% | -4.39% | |
| Form ARS Quantum-Si Inc For: Dec 31 | SEC filing · Form ARS | SEC EDGAR | -2.18% | +1.05% | |
| Form DEF 14A Quantum-Si Inc For: Apr 01 | SEC filing · Form DEF | SEC EDGAR | -2.18% | +1.05% | |
| Form DEFA14A Quantum-Si Inc | SEC filing · Form DEFA14A | SEC EDGAR | -2.18% | +1.05% | |
| Quantum-Si Announces Inducement Grants Under Nasdaq Listing Rule 5635(c)(4) | Press release | Business Wire | +1.21% | -1.20% | |
| Form 10-K Quantum-Si Inc For: Dec 31 | SEC filing · Form 10-K | SEC EDGAR | +1.02% | -4.01% | |
| Form 8-K Quantum-Si Inc For: Mar 03 | SEC filing · Form 8-K | SEC EDGAR | +1.02% | -4.01% | |
| Form S-8 Quantum-Si Inc | SEC filing · Form S-8 | SEC EDGAR | +1.02% | -4.01% | |
| Quantum-Si Reports Fourth Quarter and Full Year 2025 Financial Results | Press release | Business Wire | +1.02% | -4.01% | |
| Quantum-Si Announces Inducement Grants Under Nasdaq Listing Rule 5635(c)(4) | Press release | Business Wire | -1.68% | -5.17% | |
| Quantum-Si to Report Fourth Quarter and Full Year 2025 Financial Results on March 3, 2026 | Press release | Business Wire | -0.46% | +0.00% | |
| Quantum-Si Announces the Release of Two New Manuscripts Demonstrating the Value of Single-Molecule Protein Sequencing in Clinical Proteomics and Pathogen & Toxin Detection | Press release | Business Wire | -1.91% | -9.51% | |
| Form 8-K Quantum-Si Inc For: Dec 29 | SEC filing · Form 8-K | SEC EDGAR | -0.01% | -4.31% | |
| Quantum-Si Announces Launch of New Version 3 Library Preparation Kit and a Suite of Data Analysis Tool Enhancements | Press release | Business Wire | +1.17% | -0.78% | |
| Quantum-Si Announces Inducement Grants Under Nasdaq Listing Rule 5635(c)(4) | Press release | Business Wire | +3.75% | +1.67% | |
| Form 8-K Quantum-Si Inc For: Nov 19 | SEC filing · Form 8-K | SEC EDGAR | +1.46% | -9.49% | |
| Quantum-Si Highlights Significant Development Advancements for Proteus™ and Industry Leading Technology Pipeline at Investor & Analyst Day | Press release | Business Wire | +1.46% | -9.49% | |
| Quantum-Si to Highlight Significant Proteus™ Platform Development Progress and Provide Insights into the Company’s Industry Leading Technology Pipeline at Investor & Analyst Day | Press release | Business Wire | +3.44% | +0.79% |
Each reaction is the move the market actually made, measured from the news timestamp. Headlines link through to the QSI section they belong to.
Where else QSI is measured.
QSI earnings → · Analyst actions → · SEC filings →
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How the numbers are made.
How is Quantum-Si Incorporated - Class A's median reaction calculated?
Every labeled QSI news event is measured from its own timestamp: the last trade before the news is the base price, and the move is read at fixed horizons — 30 minutes of trading, then the close. The median across 322 events is what this page reports. Point-in-time, zero look-ahead: no event borrows information from a later one.
What counts as a positive reaction?
Any event whose price move is above zero at the horizon, relative to the last trade before the news timestamp. 45% of QSI's measured events are up at 30 minutes; the rest close the window flat or negative.
How often is this page updated?
The news table refreshes automatically as new events are labeled and priced. The reaction medians are re-pulled in batches from the dataset — the figures here are as of 2026-09-21.
Does QSI's past reaction predict its next one?
No. These are realized facts about past events, not forecasts. They describe a distribution — they say nothing certain about any future move.