GKOS vs TMDX: 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.

Reading it: TMDX 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. GKOS and TMDX 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 GKOS and TMDX 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.

Glaukos Corporation is a San Clemente, California ophthalmic medical technology and pharmaceutical company focused on glaucoma, corneal disorders, and retinal disease. It pioneered Micro-Invasive Glaucoma Surgery (MIGS) with the iStent family of implants and has expanded into sustained-release drug delivery with iDose TR (a glaucoma implant) and corneal therapies including Photrexa and the newer Epioxa cross-linking treatment for keratoconus. The company sells through eye surgeons and clinics in the US and internationally, and reported record Q1 2026 net sales of roughly $150.6 million, up about 41% year over year, with its US glaucoma franchise up roughly 58% and iDose TR contributing around $54 million.

Full GKOS guide

TransMedics Group is a commercial-stage medical-technology company built around the Organ Care System (OCS), a portable device that perfuses donor organs with warm oxygenated blood to keep them functioning and assessable outside the body, an alternative to keeping organs on ice. It has FDA approval for OCS Heart, OCS Liver, and OCS Lung, including organs recovered from donors after circulatory death (DCD), which meaningfully expands the pool of usable organs. On top of the devices, TransMedics has built a National OCS Program (NOP) that provides organ retrieval surgeons, ground transport, and a growing owned aviation fleet, so the company now earns both product revenue from disposables and service revenue from logistics.

Full TMDX guide

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

• GKOS drivers: iDose TR ramp; Corneal health and Epioxa.
• TMDX drivers: OCS adoption and DCD organ expansion; National OCS Program and owned logistics.

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: Glaukos is still unprofitable and trades at a high multiple of sales, so any slowdown in iDose TR or Epioxa adoption could pressure the stock sharply. For TMDX, transMedics depends heavily on the OCS platform and its National OCS Program, so any slowdown in transplant volumes, reimbursement changes, or clinical setbacks would hit results directly.

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 GKOS if you believe its drivers more; TMDX 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 GKOS and TMDX guides.

GKOS. Glaukos combines roughly 40% revenue growth with ongoing net losses, so it screens as a high-multiple growth medtech rather than a value name (negative trailing P/E). The debt-free balance sheet and roughly $280 million in cash fund the iDose TR and Epioxa launches. Wall Street price targets in 2026 ranged widely, from about $72 to $165, reflecting disagreement over how quickly the newer products scale.

TMDX. TransMedics traded around $76 in mid-July 2026, well below its 52-week high near $156 and closer to its low around $60, reflecting a large re-rating after margin pressure and earnings misses. The company remains profitable but thinly so, which makes valuation multiples sensitive to which earnings measure is used. The stock is priced as a high-growth medical-technology name, so continued 20%-plus revenue growth is largely an expectation rather than a cushion.

Headline figures (approximate, MAY 2026): GKOS shows revenue (ttm) ~$470M, q1 2026 net sales ~$150.6M (up ~41% YoY), 2026 revenue guidance ~$620M to $635M, q1 2026 net loss ~$19.8M (~$0.34/share); TMDX shows revenue (ttm) ~$636M, q1 2026 revenue ~$173.9M (+21% YoY), fy2026 revenue guidance ~$727M to $757M (20-25% growth), q1 2026 gross margin ~58% (down from ~61%).

GKOS and TMDX 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 GKOS and TMDX exposure against your real portfolio. It is not an investment adviser.