2025 ANNUAL REPORT I’m excited to be sharing my first letter with you as the President & CEO of Quanterix Corporation. I havebeen in this pivotal role for nearly 90 days and I am excited to convey my initial impressions of the Companyand our key near-term priorities. I am often asked why I joined Quanterix and what I see as the long-term opportunity for the Company. Forme, joining Quanterix was a matter of “Fit” and “Timing”. From a “Fit” perspective, I have spent my entirethree decade plus career in healthcare with a diverse background in pharma, tools and diagnostics in avariety of commercial and operational roles, which are very relevant for Quanterix as we scale our business.In my last role as Chief Commercial OƯicer at Illumina, I led the commercial strategy and execution for this$19B market cap company as we dove deeper into sequencing and array-based solutions and delivered oneof the most transformational technologies in the analytical instruments market. Previously, I served as the Chief Commercial OƯicer at Exact Sciences, with a team comprised of sales,marketing and customer service in precision oncology diagnostics and screening; that experience, combinedwith my prior roles at Quest, GE Healthcare and Pfizer, provides me with commercially-proven andoperational insights to accelerate Quanterix's growth. So, from a “Fit” perspective, coming to Quanterix wasvery compelling. From a “Timing” perspective, the markets Quanterix serves such as Alzheimer’s Disease, oncology, andimmunology present significant unmet medical needs that I believe Quanterix is uniquely positioned to helpsolve. The Company has tremendous potential in helping our customers improve patient care in theseimportant markets through the early detection of life-altering diseases. I am convinced that there has neverbeen a more urgent time to innovate and provide breakthrough products and services that enable ourcustomers to address these diseases. It has been an exciting start to the year for me and the team at Quanterix. We are currently working diligentlyto develop and pressure-test a detailed end-to-end plan for Quanterix that will guide our investments andhelp the company return to growth. That plan factors in the challenges facing all healthcare companies,especially those that are pioneering new approaches. At the end of the day, we are confident that trulydiƯerentiated tools and diagnostics, like the ones Quanterix has brought to market and is developing, willreceive a strong response in the marketplace. In advance of that plan being finalized and shared publicly, I want to leave you with a few key observationsfrom my first three months with Quanterix: First, I am very excited about our diagnostics business, specifically in the rapidly growing Alzheimer’s Diseasediagnostics market. This is an area that we will prioritize and focus on in the coming months. My discussionswith customers and collaborators re-aƯirmed my belief that Quanterix’s ultra-sensitive platforms and blood-based biomarker tests are uniquely positioned in this growing market. Second, we are communicating clear priorities to the organization to enable us to invest in growth platformsthat generate the most compelling long-term returns. As a smaller company, prioritizing our focus andresources is crucial for our long-term success. Third, it is evident that we have a strong foundation at Quanterix, including a talented and dedicated team,and a solid balance sheet with approximately $100 million of cash, and no debt. We finished 2025 withrobust results, despite challenging end markets. While our progress this year is likely not to be linear, aseconomic recovery across these markets may be uneven, we expect that we will once again meet our goalsand targets. In the meantime, we continue to focus on what is working well at Quanterix, and with every step forward, toensure that we are evolving Quanterix into a stronger, more agile and scalable company. I am excited about the opportunities ahead and the innovations we are creating at Quanterix. I look forward tosharing more details with you over the course of this year. Sincerely, Everett CunninghamPresident & CEOQuanterix Corporation Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. YesNo Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Exchange Act. YesNo Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or forsuch shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. YesNo Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T