HTFL vs SIEGY: Which Is the Better Buy in 2026?

Same yardstick, side by side (as of November 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. HTFL and SIEGY 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 HTFL and SIEGY 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.

Heartflow, founded in 2007 and based in Mountain View, California, sells analysis rather than hardware. A hospital or imaging center uploads a single coronary computed tomography angiography (CCTA) study, and the Heartflow One platform returns three products built off that one scan: FFRCT Analysis, which computes fractional flow reserve non-invasively to say whether a narrowing is actually restricting blood flow; RoadMap Analysis, which measures stenosis severity vessel by vessel; and Plaque Analysis, which quantifies plaque volume and composition. Each analysis is billed as a case, so revenue scales with scan volume rather than with device placements. Roughly ~93% of revenue comes from the United States, where hospitals bill FFRCT under its own CPT code (75580) and the 2021 ACC/AHA chest pain guideline made CCTA a first-line test for intermediate-risk stable chest pain.

Full HTFL guide

Siemens AG is one of Europe's largest industrial technology companies, headquartered in Munich. It runs four main businesses: Digital Industries (factory automation hardware such as PLCs and drives, plus industrial software including Xcelerator, Teamcenter, NX and the recently acquired Altair and Dotmatics), Smart Infrastructure (electrical products, grid technology and building systems, a big beneficiary of data center and electrification spending), Mobility (rail vehicles, signaling and rail software), and a roughly 67% stake in Siemens Healthineers, the medical imaging and diagnostics company that Siemens plans to separate. Fiscal years end on September 30, and US investors typically hold the company through the SIEGY sponsored ADR, which trades over the counter in dollars rather than on a US exchange. The company employs roughly 300,000 people, sells in close to 190 countries and generates a large share of revenue outside Germany, with the US and China among its biggest markets.

Full SIEGY guide

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

• HTFL drivers: Case volume compounding faster than revenue; Plaque Analysis as the second product on the same scan.
• SIEGY drivers: Electrification and data center demand at Smart Infrastructure; Industrial software and the Altair and Dotmatics deals.

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. A useful test is which set of risks you could hold through a drawdown: Competition in coronary CT AI is crowded and well funded: Cleerly, Elucid, Artrya, Circle Cardiovascular Imaging, Caristo Diagnostics and Keya Medical all have FDA-cleared CCTA analysis tools, and Heartflow's April 2026 patent suit against Cleerly in the Eastern District of Texas is an admission that the moat is being tested, with an outcome nobody can predict. For SIEGY, siemens is cyclical at the margin: an industrial slowdown, weaker China demand or a pause in data center spending would hit orders and the premium multiple at the same time.

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 HTFL if you believe its drivers more; SIEGY 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 HTFL and SIEGY guides.

HTFL. There is no price-to-earnings figure because there are no earnings, so the market is valuing Heartflow on revenue: a market capitalization near ~$4.3B against ~$212M of trailing revenue works out to roughly ~20x sales, up from ~12x in August after the stock nearly doubled over three months. That multiple assumes growth stays well above 30% and gross margin holds near ~80%. The next data point is the Q3 2026 report expected around November 11, where consensus looks for ~$65.2M of revenue and a ~$0.10 per-share loss.

SIEGY. At a Frankfurt share price around €240, Siemens trades at roughly 21 times the midpoint of its raised fiscal 2026 EPS guidance, a premium to its own history and to many diversified industrials but below pure-play electrification and automation names such as Schneider Electric. The SIEGY ADR represents one-half of an ordinary share, so its dollar price is roughly half the euro share price converted at the current exchange rate. Full fiscal 2026 results are due in mid-November 2026. The quarterly cadence matters for ADR holders: results arrive in November, February, May and August, and the ADR typically reacts in the US session following the morning German release.

Headline figures (approximate, October 2026): HTFL shows revenue (ttm) ~$212M, q2 2026 revenue ~$64.1M, up ~47.6% year over year, gross margin (ttm) ~80%, net loss ~$118M TTM; Q2 2026 ~$15.7M (EPS -$0.07 vs -$0.13 est.); SIEGY shows revenue (ttm) ~€81 billion, fiscal q3 2026 orders ~€27.9 billion (book-to-bill ~1.34), order backlog ~€132 billion, fy2026 eps pre-ppa guidance ~€11.20 to €11.50.

HTFL and SIEGY 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 HTFL and SIEGY exposure against your real portfolio. It is not an investment adviser.