BillionToOne, Inc.

S-11 d903739ds1.htm S-1

As filed with the Securities and Exchange Commission on October 7, 2025.

Registration Statement No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

**FORMS-1 **

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

(Exact name of Registrant as specified in its charter)

1035 O’Brien Drive

Menlo Park, CA 94025

**(650)460-2551 **

(Address, including zip code, and telephone number, including area code, of Registrant’s principal executive offices)

Oguzhan Atay

Chief Executive Officer

BillionToOne, Inc.

1035 O’Brien Drive

Menlo Park, CA 94025

**(650)460-2552 **

(Name, address, including zip code, and telephone number, including area code, of agent for service)

**Approximate date of commencement of proposed sale to the public:**As soon as practicable after this Registration Statement is declared effective.

If any of the securities being registered on this form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box.☐

If this form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

If this form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

If this form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, anon-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.☐

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information in this prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

Subject to Completion, dated , 2025

Preliminary prospectus

*** shares***

Class A common stock

This is an initial public offering of shares of Class A common stock of BillionToOne, Inc. We are offering shares of our Class A common stock to be sold in this offering. The initial public offering price is expected to be between $ and $ per share.

Prior to this offering, there has been no public market for our common stock. We have applied to list our Class A common stock on the Nasdaq Global Select Market under the symbol “BLLN,” and this offering is contingent upon obtaining such approval.

Following this offering, we will have two series of common stock: Class A common stock and Class B common stock. The rights of the holders of Class A common stock and Class B common stock are identical, except with respect to voting, conversion and transfer rights. Each share of Class A common stock is entitled to one vote per share. Each share of Class B common stock is entitled to 15 votes per share and is convertible at any time into one share of Class A common stock. See the section titled “Description of capital stock.” Oguzhan Atay, our Chief Executive Officer and Co-Founder, and David Tsao, our Chief Technology Officer and Co-Founder, will beneficially own 100% of our outstanding Class B common stock and, as a result, will together beneficially own approximately % of the voting power of our outstanding capital stock immediately following this offering, assuming no exercise of the underwriters’ option to purchase additional shares of Class A common stock. As a result, following this offering, our Co-Founders, together, may have significant influence over the outcome of matters submitted to our stockholders for approval, including the election of our directors and the approval of any change of control transaction.

We are an “emerging growth company” as defined under the U.S. federal securities laws and, as such, have elected to comply with certain reduced public company reporting requirements. See the section titled “Prospectus summary—Implications of being an emerging growth company.”

At our request, the underwriters have reserved up to 5% of the shares of Class A common stock being offered by this prospectus for sale, at the initial public offering price, to our officers, directors and employees through a directed share program. See the section titled “Underwriting – Directed share program.”

We have granted the underwriters an option for a period of 30 days to purchase up to additional shares of Class A common stock.

Investing in our Class A common stock involves a high degree of risk. See “Risk factors” beginning on page 22.

Neither the Securities and Exchange Commission nor any other state securities commission has approved or disapproved of these securities or passed on the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

The underwriters expect to deliver the shares to purchasers on or about , 2025.

** , 2025**

BILLION TOONE We strive to remove the fear of the unknown. Our revolutionary technology allows us to push beyond the current limitations in diagnostics so we can detect disease one molecule at a time. We provide patients with powerful and precise information about the state of their health for themselves and their children. And it's only the beginning of what we seek to do.

Key Metrics $265M+ annualized revenue run-rate (ARR)1 84% YOY revenue growth2 Emerging profitability3 $100B US annual market opportunity4 REVENUE $209M LTM revenue5 167% CAGR (2021-2024) TESTS ACCESSIONED6 508K LTM tests accessioned as of June 30, 2025 51% YOY tests accessioned growth2 1M+ tests accessioned since launch GROSS PROFIT MARGIN OTHER 65% gross profit margin 2025 14 pp YOY increase in gross profit margin2 $1.8M ARR per sales representative 225M+ covered lives7 1. Q2 2025 revenue of $66.6M annualized. Calculated as Q2 2025 revenue multiplied by 4. 2. Q2 2025 compared to Q2 2024, 3. Based on $.01 EBITDA in Q2 2025 and ($0.2M) net loss in Q2 2025. See Management’s discussion and analysis of financial condition and results of operations> > Non-GAAP financial measures for additional information and reconciliations of our non-GAAP financial measures to the most directly comparable financial measures prepared in accordance with GAAP 4. Our estimated US annual market opportunity includes important assumptions, including regarding the number of eligible patients, frequency of testing and ASPs. See Management’s discussion and analysis of financial condition and results of operations > Key factors affecting our results of operations and performance for more information regarding our total addressable market calculations and assumptions. Half of this addressable market includes early detection, an area in which we have not yet begun specific product development or commercial sales, but we believe will be strongly enabled by our existing research platform. 5. Last twelve months (LTM) revenue. Equal to sum of each month’s revenue over the prior 12 months ended June 30, 2025. 6. Number of billable tests received for processing. 7. Number of individuals covered under contracts with payors in the US as of June 30, 2025..

Key Metrics $265M+ annualized revenue run-rate (ARR)1 86% YOY revenue growth2 Emerging profitability3 $100B US annual market opportunity4 REVENUE $209M LTM revenue5 167% CAGR (2021-2024) TESTS ACCESSIONED6 508K LTM tests accessioned as of Jun 30, 2025 51% YOY tests accessioned growth2 1M+ tests accessioned since launch GROSS PROFIT MARGIN 65% gross profit margin H1 2025 14 pp YOY increase in gross profit margin2 OTHER $1.8M ARR per sales representative 225M+ covered lives7 1. Q2 2025 revenue of $66.6M annualized. Calculated as Q2 2025 revenue multiplied by 4. 2. Q2 2025 over Q2 2024. 3. Based on $0.1M EBITDA in Q2 2025 and ($0.2M) net loss in Q2 2025. 4. Our estimated US annual market opportunity includes important assumptions, including regarding the number of eligible patients, frequency of testing and ASPs. See Management's discussion and analysis of financial condition and results of operations > Key factors affecting our results of operations and performance for more information regarding our total addressable market calculations and assumptions. Half of this addressable market includes early detection, an area in which we have not yet begun specific product development or commercial sales, but we believe will be strongly enabled by our existing research platform. 5. Last twelve months (LTM) revenue. Equal to sum of each month's revenue over the prior 12 months ended Jun 30, 2025. 6. Number of billable tests received for processing. 7. Number of individuals covered under contracts with payors in the US as of Jun 30, 2025.

Our Impact Marina* was excited about her pregnancy at 9 weeks. That was when she took the Billion ToOne's UNITY Fetal RiskTM Screen test, which revealed she was a carrier for cystic fibrosis. However, the same report also showed her baby had an extremely low risk of having the disease (1 in 5000). While initially surprised, Marina felt much less anxious and more at ease with her pregnancy than she would have with traditional carrier screening. Traditional methods would have only identified her carrier status and required her partner to undergo further testing to assess the baby's risk. Juan* was unfortunately diagnosed with stage IV lung cancer.After his initial biopsy, Juan's doctor requested BilliontoOne's Northstar Select® blood test to help him determine which treatment would work best. Northstar Select uncovered EGFR mutation at 0.05% variant allele fraction (VAF), a highly actionable cancer variant that has a known targeted therapy. Cancers at this low level of VAF are often missed by other cancer tests**. Thanks to Northstar Select, Juan was able to start on the best therapy for his cancer and his doctor can easily monitor his progress using Northstar ResponseR. * Actual customer stories. Names have been changed to preserve patients' privacy and the photos are actor portrayals. ** Other liquid biopsy tests have an LOD that ranges between 0.25% - 0.50% (e.g. TSO500 at 0.5% VAF for SNVs) whereas Northstar Select has demonstrated an LOD of 0.15%, representing a 2x higher sensitivity than other assays.

Our Revenue Growth Revenue Growth 167% CAGR $8M $26M $72M $153M $69M $126M 2021 2022 2023 2024 H1 2024 unaudited H1 2025 unaudited Net Loss ($42M) ($80M) ($83M) ($42M) ($15M) ($4M) Net Margin (520%) (303%) (115%) (27%) (22%) (3%)