BillionToOne, Inc.

Special Note Regarding Forward-Looking Statements

This Quarterly Report on Form 10-Q (this “Quarterly Report”) contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and other federal securities laws. All statements other than statements of historical facts contained in this Quarterly Report, including statements regarding our future operating results and financial position, our business strategy and plans, our market growth, and our objectives for future operations, are forward-looking statements.

The words “believe,” “may,” “will,” “estimate,” “continue,” “anticipate,” “design,” “intend,” “expect,” “forecast,” “could,” “plan,” “potential,” “predict,” “seek,” “target,” “should,” “would,” or the negative version of these words and similar expressions are intended to identify forward-looking statements. We have based these forward-looking statements on our current expectations and projections about future events and trends that we believe may affect our financial condition, results of operations, strategy, short- and long-term business operations and objectives, and financial needs. Forward-looking statements contained in this Quarterly Report include, but are not limited to, statements about:

•the level of demand for any of our products, which may vary significantly;

•our ability to increase the adoption of our products in the prenatal and oncology markets and in large healthcare systems;

•our ability to generate persuasive clinical validity and utility evidence;

•our ability to expand our portfolio of molecular diagnostic tests;

•our ability to use AI effectively and efficiently;

•our ability to execute our reimbursement strategy and expand coverage of our tests;

•our ability to replicate positive results from trials or studies conducted by us or third parties in current or future trials or studies;

•the potential for our UNITY Fetal Antigen CTA to become the first NIPT to have a companion diagnostics indication pending;

•the successful completion of Johnson & Johnson’s AZALEA Phase 3 clinical trial;

•the implementation of our business model and strategic plans;

•the size and growth potential of the total addressable markets for our current and future products and our ability to serve those markets;

•our ability to realize the benefits of current and future collaborations for the development of our products;

•our ability to maintain, expand and protect our intellectual property;

•developments relating to our competitors and our industry, including with respect to the possibility of competitors initiating legal proceedings against us;

•existing regulations and regulatory developments in the United States and other jurisdictions;

•general economic, industry, and market conditions, including tariffs and inflation;

•our ability to attract, hire, and retain our key personnel and additional qualified personnel;

•our ability to remediate our material weaknesses in our internal control over financial reporting;

•our anticipated use of our existing cash and cash equivalents;

•our estimates regarding expenses, future revenue, capital requirements and needs for additional financing; and

•other risks and uncertainties, including those listed in the section titled “Risk Factors.”

We caution you that the foregoing list may not contain all of the forward-looking statements made in this Quarterly Report.

These forward-looking statements are subject to a number of risks, uncertainties, and assumptions, including those described in the section titled “Risk Factors.” Moreover, we operate in a very competitive and rapidly changing environment. New risks emerge from time to time. It is not possible for our management to predict all risks, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements we may make. In light of these risks, uncertainties, and assumptions, the forward-looking events and circumstances discussed in this Quarterly Report may not occur and actual results could differ materially and adversely from those anticipated or implied in the forward-looking statements.

You should not rely upon forward-looking statements as predictions of future events. Although we believe that the expectations reflected in the forward-looking statements are reasonable, we cannot guarantee future results, performance or achievements. The forward-looking statements made in this Quarterly Report are given only as of the date on which the statements are made. We undertake no obligation to update any of these forward-looking statements for any reason after the date of this Quarterly Report or to conform these statements to actual results or to changes in our expectations, except as required by law.

In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this Quarterly Report, and while we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into or review of all potentially available relevant information. These statements are inherently uncertain and investors are cautioned not to unduly rely upon these statements.