ABVX vs NBTX: Which Is the Better Buy in 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.

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. ABVX and NBTX 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 ABVX and NBTX 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.

Abivax SA is a French clinical-stage biopharmaceutical company listed on Nasdaq via a sponsored ADR (ABVX). Its lead and effectively sole value driver is obefazimod (formerly ABX464), a first-in-class oral miR-124 enhancer being developed for inflammatory bowel disease. In 2025 and 2026 the pivotal Phase 3 ABTECT program in moderate-to-severe ulcerative colitis reported positive results across both induction trials and the maintenance trial, with the 50 mg dose showing clinical remission around 51% at Week 44 versus roughly 10% for placebo. Management has guided toward a U.S. FDA new drug application filing in late 2026, with a Phase 2b Crohn's disease readout expected around mid-2027.

Full ABVX guide

Nanobiotix S.A. is a clinical-stage nanomedicine company headquartered in France and dual-listed on Nasdaq (as American Depositary Shares under NBTX) and Euronext Paris. Its lead product candidate, NBTXR3 (also called JNJ-1900), is a radioenhancer: injectable nanoparticles that are placed directly into a tumor and, when activated by standard radiotherapy, are designed to boost the radiation's tumor-killing effect. In late 2023 the company signed a global license and collaboration with Johnson & Johnson's Janssen unit, which now sponsors and operates the pivotal Phase 3 NANORAY-312 study in head and neck cancer and broader development across other solid tumors.

Full NBTX guide

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

• ABVX drivers: Positive Phase 3 obefazimod data; Path to an FDA filing.
• NBTX drivers: Johnson & Johnson partnership; NANORAY-312 head and neck readout.

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: As a single-asset biotech, essentially all of Abivax's value depends on obefazimod, so a regulatory rejection, a delay, or a negative safety finding could sharply reduce the shares. For NBTX, the dominant risk is clinical and binary: NBTXR3 remains unapproved, and a failed or delayed NANORAY-312 Phase 3 could erase much of the equity value in a single day.

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 ABVX if you believe its drivers more; NBTX 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 ABVX and NBTX guides.

ABVX. Abivax has effectively no product revenue and posts large net losses, which is normal for a clinical-stage biotech funding pivotal trials rather than a warning sign on its own. Traditional earnings multiples do not apply; the market instead values the probability-weighted potential of obefazimod reaching and selling in the market. The mid-2026 capital raise materially extended the runway and reduced near-term financing risk.

NBTX. Standard price-to-earnings valuation does not apply because Nanobiotix is pre-approval and its reported revenue stems mostly from the J&J agreement rather than product sales. The market instead prices the probability-weighted value of NBTXR3 across head and neck, lung, and other tumors, net of dilution risk. That is why the roughly $1.5 billion market value sits far above trailing revenue and coexists with ongoing net losses.

Headline figures (approximate, July 2026): ABVX shows market cap ~$7-8B, product revenue (ttm) ~negligible (pre-commercial), net loss (fy2025) ~EUR 336M, r&d expense (fy2025) ~EUR 178M; NBTX shows market cap ~$1.5B, revenue (fy2025) ~$36M (~EUR 32.6M, largely J&J-agreement, non-product), net loss (fy2025) ~$26M (~EUR 24.0M), cash (dec 31, 2025) ~$58M (~EUR 52.8M).

ABVX and NBTX 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 ABVX and NBTX exposure against your real portfolio. It is not an investment adviser.