BillionToOne, Inc. (BLLN) Stock Price & How to Invest

BillionToOne is a Menlo Park diagnostics company founded in 2016 by Oguzhan Atay, David Tsao and Sukrit Silas around a patented technique called Quantitative Counting Templates, which lets the company count individual DNA molecules in a blood sample rather than merely detect them. That precision is what the product line is built on. The prenatal franchise, sold under the Unity brand, screens a pregnancy from a maternal blood draw for chromosomal conditions, single-gene disorders, and fetal RhD and antigen status, and it produced about $94.2 million of the $109.4 million booked in the second quarter of 2026. The oncology franchise, sold as Northstar, includes Northstar Select (an 84-gene circulating tumor DNA panel used to pick a therapy for advanced solid tumors) and Northstar Response (a treatment-monitoring assay), and it grew about 176% year over year to $13.7 million in the same quarter. A small clinical-trial services line rounds out revenue.

The investment picture is a scaling story with a valuation attached to it. Revenue roughly doubled in 2025 to about $305 million, is guided to $450 million to $465 million for 2026, and reached about $397 million on a trailing twelve-month basis by mid-2026. Unlike most diagnostics companies at that stage, BillionToOne is making money: gross margin reached about 70% in the second quarter of 2026 (up from roughly 53% in 2024), GAAP operating income was about $5.5 million in the quarter, and first-half net income was about $26 million against a loss a year earlier. The company holds roughly $549 million of cash against about $144 million of debt, so growth is self-funded. What the market has not settled is what that deserves to cost. The stock IPO'd at $60 in November 2025, ran to about $150 by August 2026, then fell roughly 39% in one day when second-quarter revenue of $109.4 million landed slightly under the roughly $111.6 million consensus and non-GAAP earnings of $0.15 came in below the roughly $0.19 modeled, with full-year guidance reiterated rather than raised. Illumina is also suing the company over three non-invasive prenatal testing patents that read directly on the Unity line.

Illumina sued BillionToOne in the District of Delaware in May 2026 alleging infringement of three patents covering fetal fraction measurement and variant identification in mixed DNA samples, and the complaint targets the Unity products that supply most of the revenue, so an adverse outcome could mean royalties, an injunction, or a redesign of the core franchise. Revenue depends heavily on payer reimbursement decisions and on average selling price holding up, and a coverage change at a large commercial payer or a Medicare rate revision would show up directly in the growth rate without any change in test volume. Natera remains far larger in non-invasive prenatal testing and Guardant Health, Foundation Medicine, Tempus and Caris are entrenched in oncology liquid biopsy, so both franchises compete against companies with more scale and longer payer relationships. The valuation carries essentially no cushion: the stock traded at roughly 119 times trailing earnings before the August 2026 drop and still around 9 to 11 times forward revenue after it, which is why an in-line quarter produced a 39% single-day decline. Governance is concentrated, with Class B shares carrying 15 votes each and the two founders controlling roughly 64% of voting power at the time of the IPO, and the post-IPO lockup expired on May 5, 2026, with insider sales reported since.

7 analysts publish price targets on BLLN, averaging $122.43 against a $91.65 price as of August 2026, or +33.6%. The published targets run from $90.00 to $145.00, a moderate spread, and the ratings split 6 buy, 2 hold, 0 sell. Over the last six months there have been 3 raises and 5 cuts among the published actions. A price target is what an analyst published on a date, not a prediction, and sell-side ratings skew positive across the whole market.

Read the full BLLN forecast and price target for the target table, the recent rating actions by firm, and how the consensus has shifted.

We give no verdict on BillionToOne, Inc.. Both cases are real, which is why the question is contested at all, so here is the strongest version of each.

The case for buying. Share gains and menu expansion in prenatal screening. Unity is the revenue engine, at about $94.2 million in the second quarter of 2026 and up roughly 55% year over year, and the company has taken meaningful share in a US market long dominated by Natera. The most optimistic published target, $145.00, assumes this works close to its best case.

The case against. Illumina sued BillionToOne in the District of Delaware in May 2026 alleging infringement of three patents covering fetal fraction measurement and variant identification in mixed DNA samples, and the complaint targets the Unity products that supply most of the revenue, so an adverse outcome could mean royalties, an injunction, or a redesign of the core franchise. The most pessimistic target, $90.00, is roughly what BLLN is worth if this bites instead.

Read the full bull and bear case on BLLN, including what would have to change to break either one. Walnut is not an investment adviser.

A simple financial snapshot. These are approximations and refresh quarterly; for current figures see BillionToOne, Inc.'s investor relations page or your broker.

• Revenue (TTM): ~$397 million, up ~90% year over year
• Q2 2026 revenue: ~$109.4 million, up ~64%, versus ~$111.6 million expected
• 2026 revenue guidance: ~$450 million to $465 million, reiterated (implies ~48% to 52% growth)
• Gross margin: ~70% in Q2 2026, up from ~65% a year earlier and ~53% in 2024
• Net income (TTM): ~$38 million; Q2 2026 net income ~$8.1 million, or ~$0.15 per diluted share
• Market cap / valuation: ~$4.3 billion near $92 a share, ~119x trailing earnings, ~9x to 11x forward revenue

The multiple is the whole argument. At roughly 119 times trailing earnings even after a 39% drawdown, BLLN is priced on the forward revenue ramp rather than on current profits, which are real but small (about $38 million trailing against a $4.3 billion market value). Cash of roughly $549 million against about $144 million of debt removes financing risk from the story, so the debate narrows to whether 48% to 52% growth in 2026 can be sustained into 2027 as the prenatal base gets larger and the Illumina litigation runs. The stock's 52-week range of roughly $62 to $150 against a $60 IPO price in November 2025 shows how little consensus there is on the answer.

Other names that sit close to BLLN: same theme, named as a direct competitor, or held beside it in the same funds. Each entry says which. Worth a look if you are thinking about diversification within a thesis rather than concentration on one ticker.

There are three common ways to get BLLN exposure. Buy shares (or fractional shares) directly at any major broker. Hold an ETF that includes it, which spreads the position across many companies. Or build it into a focused thematic portfolio, so BLLN sits alongside other stocks that express the same thesis.

Walnut takes the portfolio route. Describe a thesis where BLLN fits (for example “AI infrastructure” or “dividend-growth large-caps”) and the AI proposes 5 to 6 constituents with target weights. You review the plan and fund it through your own broker when you're ready.

New to this? Start with how to invest in stocks, see how to analyze a stock with AI, or compare the best AI stock analyzers.

BillionToOne pairs unusually fast growth with real profitability in a category where neither is common, and the stock's behavior shows the market is pricing execution with very little margin for a merely in-line quarter.

Whether BLLN is worth buying today depends more on your time horizon and what you already hold than on any single call. We walk through valuation, what would have to go right, and the risks in is BLLN a buy or a sell?, and where the stock could go from here in the BLLN stock forecast.

For income investors, whether BLLN pays a dividend and how the payout looks is covered in does BLLN pay a dividend? And to weigh BLLN against a peer, read the full side-by-side comparisons: BLLN vs LH and BLLN vs DGX.