IFNNY vs STM: 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.

Reading it: IFNNY 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. IFNNY and STM 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 IFNNY and STM 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.

Infineon Technologies AG designs and manufactures semiconductors used wherever electricity has to be converted, switched or controlled: electric drivetrains, chargers, solar inverters, wind turbines, trains, industrial motors, server power supplies and phone chargers, plus microcontrollers, sensors and security chips. In fiscal 2025 (the year to September 30, 2025) revenue was €14.66 billion, down 2%, with a Segment Result margin of 17.5%. Automotive (ATV) brought in €7.40 billion, or about half of sales, at a €1.53 billion Segment Result. Power & Sensor Systems (PSS), home of the AI server power business, grew 11% to €4.21 billion. Green Industrial Power (GIP) fell 16% to €1.63 billion and Connected Secure Systems (CSS) fell 6% to €1.42 billion. Greater China was the largest region at 38% of revenue, followed by Europe, the Middle East and Africa at 24%, the rest of Asia-Pacific at 17%, the Americas at 12% and Japan at 9%.

Full IFNNY guide

STMicroelectronics designs and manufactures a broad range of semiconductors, including analog chips, power and discrete devices (notably silicon carbide, where it holds the largest global share at roughly a third of the market), microcontrollers, MEMS sensors, and RF products. Its customers are concentrated in automotive (electrification, ADAS, body and safety electronics) and industrial (factory automation, power conversion, energy), with a more cyclical consumer and personal-electronics business layered on top. Unlike fabless designers, ST owns its fabs, which makes it capital-intensive and highly sensitive to factory utilization, a dynamic that has weighed heavily on margins during the recent downturn.

Full STM guide

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

• IFNNY drivers: Power supplies for AI data centers; Margin recovery from better factory loading.
• STM drivers: Silicon carbide and automotive electrification; Cyclical recovery off the trough.

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: Infineon's earnings are cyclical, and fiscal 2025 showed how quickly they can fall: revenue dropped 2% and Segment Result fell from €3.1 billion to €2.6 billion as customers cut inventories and factories ran below capacity. For STM, sTM is deeply cyclical and capital-intensive, so weak factory utilization can compress margins sharply, as it did in 2025 when operating margin fell near breakeven.

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 IFNNY if you believe its drivers more; STM 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 IFNNY and STM guides.

IFNNY. Trailing revenue of about €15.6 billion combines the September 2025 quarter (€3.94 billion) with the first three quarters of fiscal 2026 (€3.66 billion, €3.81 billion and €4.17 billion), so it understates the run rate if the guided €4.7 billion September quarter arrives. Adjusted diluted EPS was €0.44 in the June quarter, up from €0.34 in March, against a share price near €59, which means the valuation depends heavily on margins continuing toward the guided 23%. Adjusted free cash flow guidance is about €1.85 billion for fiscal 2026, while reported free cash flow of about €0.9 billion is lower because it includes the ams OSRAM purchase and frontend building investment. Full-year results are due on November 10, 2026.

STM. STM's valuation looks expensive on forward earnings largely because profits are depressed at the bottom of the cycle, not because the business is structurally rich. Revenue troughed near $3.1 billion in Q1 2026 with gross margin around 33.8%, well below the 44 to 46% level management targets in its longer-term model. The multiple therefore embeds an expectation that margins and earnings recover meaningfully over the next couple of years.

Headline figures (approximate, October 2026): IFNNY shows revenue (ttm to june 2026) ~€15.6B, fy2026 revenue guidance ~€16.3B (~11% growth), q3 fy2026 segment result margin 19.1% (Q4 guided ~23%), market cap ~€77B (~$86B; IFNNY ~$66); STM shows revenue (ttm) ~$12B, fy2025 revenue ~$11.8B (down ~11%), q1 2026 revenue ~$3.1B (up ~23% YoY), q1 2026 gross margin ~33.8%.

IFNNY and STM 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 IFNNY and STM exposure against your real portfolio. It is not an investment adviser.