ILMN vs TEM: Which Is the Better Buy in 2026?

Same yardstick, side by side (as of October 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. ILMN and TEM 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 ILMN and TEM 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.

Illumina designs, makes, and sells next-generation DNA sequencing systems and the consumables that run on them, serving research, clinical, and applied-genomics customers. Its business follows a razor-and-blades model: instruments such as the high-throughput NovaSeq X, the NextSeq, and the benchtop MiSeq seed an installed base, and the bulk of revenue then comes from recurring sequencing consumables (reagents and flow cells), which historically make up the majority of sales. The company is also pushing into multiomics, proteomics, and clinical diagnostics to expand what its platforms can measure. Illumina is headquartered in San Diego, was founded in 1998, and is led by CEO Jacob Thaysen.

Full ILMN guide

Tempus AI (NASDAQ: TEM) is a Chicago-based technology company that applies artificial intelligence to precision medicine, primarily in oncology but increasingly across cardiology, neuropsychiatry, and hereditary conditions. It operates two interconnected business lines: a diagnostics segment that performs next-generation sequencing (NGS), PCR profiling, molecular pathology, and hereditary genetic tests through CAP-accredited, CLIA-certified laboratories, charging on a per-test basis; and a Data and Applications segment that licenses de-identified, linked clinical, molecular, and imaging datasets to life sciences companies (Insights), offers clinical trial matching (Trials), and deploys AI-powered algorithm products for physicians (Algos) and an AI platform called Next. Approximately 95% of the top 20 pharmaceutical companies use Tempus data or trial services, and the platform has integrations across more than 7,000 physicians and hundreds of research partners, creating a self-reinforcing network where clinical volume generates data that improves AI models and attracts more customers.

Full TEM guide

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

• ILMN drivers: Installed base and the consumables annuity; The NovaSeq X transition.
• TEM drivers: Explosive Revenue Growth with a Clear Path to Profitability; Data Licensing as a High-Margin Flywheel.

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: Competition is intensifying: Ultima Genomics markets bulk whole-genome sequencing near $80 a genome, Element Biosciences' AVITI undercuts benchtop economics, and PacBio and Oxford Nanopore hold long-read niches, all pressuring Illumina's pricing and share. For TEM, tempus remains unprofitable on a GAAP basis, with a full-year 2025 net loss of $245 million (which included $136 million in stock-based compensation), and the path to sustained GAAP profitability is long; Q1 2026 showed a net loss of $125.9 million, widening 85% year-over-year, and EPS missed analyst estimates by 34%.

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 ILMN if you believe its drivers more; TEM 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 ILMN and TEM guides.

ILMN. Illumina's multiple has expanded far faster than its earnings: the shares are up about 94% year to date and 172% over a year, while consensus calls for 2026 revenue growth near 11% and EPS of about $5.36. At roughly 43 times forward earnings and 36 times EV/EBITDA, the price assumes growth and margin expansion continue well beyond 2026, and the stock sits above the $241 average analyst target even as individual targets, such as JPMorgan's move to $320, have risen.

TEM. As of October 16, 2026, Tempus trades near $66 per share, roughly 8.3 times trailing revenue, a richer multiple than mid-2026 after the stock's summer rally. The P/E is not meaningful because the company is still loss-making on a trailing basis, and consensus still expects a small loss per share in 2027, though gross margin near 64 percent is at software-like levels. The analyst mean target is about $75, and third-quarter results on November 2, 2026 are the next checkpoint.

Headline figures (approximate, October 2026): ILMN shows revenue (ttm) ~$4.49 billion; Q2 2026 revenue ~$1.16 billion, up ~9% year over year, 2026 revenue consensus ~$4.62 billion (~11% growth); 2027 consensus ~$4.92 billion, margins (ttm) Gross ~68%, operating ~21%, net ~18%, net income and eps (ttm) ~$824 million net income; EPS ~$5.39 trailing, ~$6.12 forward; TEM shows revenue (ttm) ~$1.43 billion, q2 2026 revenue (most recent quarter) ~$382 million (up ~22% YoY), gross margin (ttm) ~64%, operating margin (ttm) ~-20%.

ILMN and TEM 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 ILMN and TEM exposure against your real portfolio. It is not an investment adviser.