BLLN vs DGX: How BillionToOne, Inc. and Quest Diagnostics Compare (2026)

Same yardstick, side by side (as of August 2026). Valuation lined up like this is most meaningful for two names in the same corner of the market, which these are. Figures are approximate; verify before investing.

Reading it: DGX is the cheaper of the two on forward earnings, but cheaper is not the same as better. Pair the valuation with growth (how far the forward P/E sits below the trailing P/E) and risk (beta) before you decide.

The metrics above tell you which is the marginally better business. The bigger risk for most people is not picking the slightly worse stock, it is over-concentrating. BLLN and DGX share themes, so owning both, or adding either to what you already hold, can quietly push a large share of your portfolio into one bet.

This is the part a generic comparison page cannot answer, because it depends on what you own. Connect your brokerage and Walnut shows your real, combined BLLN and DGX exposure, flags overlap with your existing positions, and tells you if adding one would tip you past a concentration you are comfortable with, read-only by default, with your login staying at your broker. Walnut is not an investment adviser.

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.

Full BLLN guide

Quest Diagnostics operates one of the largest clinical laboratory networks in the United States, processing billions of test results a year across a footprint of patient service centers, hospital and physician outreach relationships, and consumer-initiated testing. Its core Diagnostic Information Services segment spans routine testing (blood counts, cholesterol, metabolic panels) plus a growing base of advanced molecular and genomic diagnostics in oncology, neurology, women's health, and infectious disease. Scale, a national logistics network, and long-standing payer contracts are the company's main moats in a fragmented roughly $100 billion US lab market where Quest and Labcorp together hold the top tier.

Full DGX guide

Both fit overlapping themes, but they are not interchangeable. The useful comparison is which set of drivers and risks you want exposure to.

• BLLN drivers: Share gains and menu expansion in prenatal screening; Oncology as the second engine.
• DGX drivers: Organic volume growth; Acquisitions as a growth engine.

A faster-growing, richer-valued name usually swings harder, so it suits a longer horizon and a higher tolerance for volatility; a steadier, more cash-generative business suits a more conservative or income-minded investor. The honest test is which set of risks you could hold through a drawdown: 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. For DGX, the largest risk is reimbursement policy: Medicare rates under PAMA face potential cuts (a delay pushed reductions toward 2027, but a roughly 15 percent cut to hundreds of tests looms without permanent reform), and private-payer pricing pressure caps growth.

Growth-minded investors who believe the theme has years to run tend to accept the richer multiple for more upside; value-minded investors lean toward the cheaper forward earnings and steadier profile. Pick BLLN if you believe its drivers more; DGX if you believe its. Many investors hold both, but since they share themes, that is a concentrated bet, not diversification. Decide deliberately and check overlap. For the full detail, see the BLLN and DGX guides.

BLLN. 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.

DGX. In Q1 2026 Quest reported revenue of about $2.9 billion (up 9.2 percent) and adjusted EPS of $2.50 (up 13.1 percent), and raised full-year guidance. The stock traded near $205 in mid-July 2026 at a forward P/E under 20, a moderate multiple below primary competitor Labcorp. The dividend has risen for 15 consecutive years, most recently a 7.5 percent increase.

Headline figures (approximate, August 2026): BLLN shows 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; DGX shows revenue (ttm) ~$11.5B, 2026 revenue guidance ~$11.78B to $11.9B, 2026 adj. eps guidance ~$10.63 to $10.83, market cap ~$22.8B.

BLLN and DGX are related but distinct: same themes, different businesses and risks. Neither wins in the abstract; the right pick is whichever thesis you actually believe, sized so you are not over-concentrated in one theme. Walnut can show your combined BLLN and DGX exposure against your real portfolio. It is not an investment adviser.